ALBERT

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Remote Sensing of Environment, Volume 219〈/p〉 〈p〉Author(s): J. Antonio Guzmán Q., Benoit Rivard, G. Arturo Sánchez-Azofeifa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Increases in liana abundance in tropical forests are pervasive threats to the current and future forest carbon stocks. Never before has the need been more evident for new approaches to detect the presence of liana in ecosystems, given their significance as fingerprints of global environmental change. In this study, we explore the use of longwave infrared reflectance (LWIR, 8–11 μm) as a wavelength region for the classification of liana and tree leaves and compare classification results with those obtained using visible-near infrared reflectance data (VIS-NIR, 0.45–0.95 μm). Twenty sun leaves were collected from each of 14 liana species and 21 tree species located at the canopy or forest edge (〈em〉n〈/em〉 = 700) in Santa Rosa National Park, Costa Rica. LWIR and VIS-NIR reflectance measurements were performed on these leaves using a portable calibrated Fourier Transform Infrared Spectroscopy (FTIR) Agilent ExoScan 4100 and a UniSpec spectral analysis system, respectively. The VIS-NIR and LWIR data were first resampled. Then these two spectral libraries were pre-processed for noise reduction and spectral feature enhancement resulting in three datasets for each spectral region as follows: filtered only, filtered followed by extraction of the first derivative, and continuous wavelet transformation (CWT). Data reduction was then applied to these data sets using principal components analysis (PCA). The outputs obtained from the PCA were used to conduct the supervised classification of liana and tree leaves. In total, 21 classifiers were applied to datasets of training and testing to extract the classification accuracy and agreement for liana and tree leaves. The results suggest that the classification of leaves based on LWIR data can reach accuracy values between 66 and 96% and agreement values between 32 and 92%, regardless of the type of classifier. In contrast, the classification based on VIS-NIR data shows accuracy values between 50 and 70% and agreement values between 0.01 and 40%. The highest classification rates of liana and tree leaves were obtained from datasets pre-processed using the CWT or from the extraction of the first derivative and classified using either random forest, 〈em〉k〈/em〉-nearest neighbor, or support vector machine with radial kernel. The results using the LWIR reflectance highlight the potential of this spectral region for the accurate detection of liana extent in tropical ecosystems. Future studies should consider this potential and test the regional monitoring of lianas.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Remote Sensing of Environment, Volume 219〈/p〉 〈p〉Author(s): Adam J. Purdy, Joshua B. Fisher, Michael L. Goulden, Andreas Colliander, Gregory Halverson, Kevin Tu, James S. Famiglietti〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Accurate estimation of global evapotranspiration (ET) is essential to understand water cycle and land-atmosphere feedbacks in the Earth system. Satellite-driven ET models provide global estimates, but many of the ET algorithms have been designed independently of soil moisture observations. As water for ET is sourced from the soil, incorporating soil moisture into global remote sensing algorithms of ET should, in theory, improve performance, especially in water-limited regions. This paper presents an update to the widely-used Priestley Taylor-Jet Propulsion Laboratory (PT-JPL) ET algorithm to incorporate spatially explicit daily surface soil moisture control on soil evaporation and canopy transpiration. The updated algorithm is evaluated using 14 AmeriFlux eddy covariance towers co-located with COsmic-ray Soil Moisture Observing System (COSMOS) soil moisture observations. The new PT-JPL〈sub〉SM〈/sub〉 model shows reduced errors and increased explanation of variance, with the greatest improvements in water-limited regions. Soil moisture incorporation into soil evaporation improves ET estimates by reducing bias and RMSE by 29.9% and 22.7% respectively, while soil moisture incorporation into transpiration improves ET estimates by reducing bias by 30.2%, RMSE by 16.9%. We apply the algorithm globally using soil moisture observations from the Soil Moisture Active Passive Mission (SMAP). These new global estimates of ET show reduced error at finer spatial resolutions and provide a rich dataset to evaluate land surface and climate models, vegetation response to changes in water availability and environmental conditions, and anthropogenic perturbations to the water cycle.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 19 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Remote Sensing of Environment〈/p〉 〈p〉Author(s): Sylvain Jay, Frédéric Baret, Dan Dutartre, Ghislain Malatesta, Stéphanie Héno, Alexis Comar, Marie Weiss, Fabienne Maupas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The recent emergence of unmanned aerial vehicles (UAV) has opened a new horizon in vegetation remote sensing, especially for agricultural applications. However, the benefits of UAV centimeter-scale imagery are still unclear compared to coarser resolution data acquired from satellites or aircrafts. This study aims (i) to propose novel methods for retrieving canopy variables from UAV multispectral observations, and (ii) to investigate to what extent the use of such centimeter-scale imagery makes it possible to improve the estimation of leaf and canopy variables in sugar beet crops (〈em〉Beta vulgaris〈/em〉 L.). Five important structural and biochemical plant traits are considered: green fraction (GF), green area index (GAI), leaf chlorophyll content (C〈sub〉ab〈/sub〉), as well as canopy chlorophyll (CCC) and nitrogen (CNC) contents.〈/p〉 〈p〉Based on a comprehensive data set encompassing a large variability in canopy structure and biochemistry, the results obtained for every targeted trait demonstrate the superiority of centimeter-resolution methods over two standard remote-sensing approaches (i.e., vegetation indices and PROSAIL inversion) applied to average canopy reflectances. Two variables (denoted GF〈sub〉GREENPIX〈/sub〉 and VI〈sub〉CAB〈/sub〉) extracted from the images are shown to play a major role in these performances. GF〈sub〉GREENPIX〈/sub〉 is the GF estimate obtained by thresholding the Visible Atmospherically Resistant Index (〈em〉VARI〈/em〉) image, and is shown to be an accurate and robust (e.g., against variable illumination conditions) proxy of the structure of sugar beet canopies, i.e., GF and GAI. VI〈sub〉CAB〈/sub〉 is the 〈em〉mND〈/em〉〈sub〉〈em〉blue〈/em〉〈/sub〉 index value averaged over the darkest green pixels, and provides critical information on C〈sub〉ab〈/sub〉. When exploited within uni- or multivariate empirical models, these two variables improve the GF, GAI, C〈sub〉ab〈/sub〉, CCC and CNC estimates obtained with standard approaches, with gains in estimation accuracy of 24, 8, 26, 37 and 8%, respectively. For example, the best CCC estimates (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.90) are obtained by multiplying C〈sub〉ab〈/sub〉 and GAI estimates respectively derived from VI〈sub〉CAB〈/sub〉 and a log-transformed version of GF〈sub〉GREENPIX〈/sub〉, log(1-GF〈sub〉GREENPIX〈/sub〉).〈/p〉 〈p〉The GF〈sub〉GREENPIX〈/sub〉 and VI〈sub〉CAB〈/sub〉 variables, which are only accessible from centimeter-scale imagery, contributes to a better identification of the effects of canopy structure and leaf biochemistry, whose influences may be confounded when considering coarser resolution observations. Such results emphasize the strong benefits of centimeter-scale UAV imagery over satellite or airborne remote sensing, and demonstrate the relevance of low-cost multispectral cameras to retrieve a number of plant traits, e.g., for agricultural applications.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Remote Sensing of Environment, Volume 219〈/p〉 〈p〉Author(s): Huan Li, Hongjie Xie, Stefan Kern, Wei Wan, Burcu Ozsoy, Stephan Ackley, Yang Hong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We use total (sea ice plus snow) freeboard as estimated from Ice, Cloud and land Elevation Satellite (ICESat) Geophysical Laser Altimeter System (GLAS) observations to compute Antarctic sea-ice thickness and volume. In order to overcome assumptions made about the relationship between snow depth and total freeboard or biases in snow depth products from satellite microwave radiometry, we implement a new algorithm. We treat the sea ice-snow system as one layer with reduced density, which we approximate by means of a priori information about the snow depth to sea-ice thickness ratio. We derive this a priori information directly from ICESat total freeboard data using empirical equations relating in-situ measurements of total freeboard to snow depth or sea-ice thickness. We apply our new algorithm (one-layer method or OLM), which uses the buoyancy equation approach without the need for auxiliary snow depth data, to compute sea-ice thickness for every ICESat GLAS footprint from a valid total freeboard. An improved method for sea-ice volume retrieval is also used to derive ice volume at 6.25 km scale. Spatio-temporal variations of sea-ice thickness and volume are then analyzed in the circumpolar Antarctic as well as its six sea sectors: Pacific Ocean, Indian Ocean, Weddell East, Weddell West, Bell-Amund Sea, and Ross Sea, under both interannual and seasonal scales. Because the OLM algorithm relies on only one parameter, the total freeboard, and is independent of auxiliary snow depth information, it is believed to become a viable alternative sea-ice thickness retrieval method for satellite altimetry.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 19 June 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Remote Sensing of Environment〈/p〉 〈p〉Author(s): Xinjie Liu, Luis Guanter, Liangyun Liu, Alexander Damm, Zbyněk Malenovský, Uwe Rascher, Dailiang Peng, Shanshan Du, Jean-Philippe Gastellu-Etchegorry〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Solar-induced chlorophyll fluorescence (SIF), an electromagnetic signal that can potentially indicate vegetation photosynthetic activity, can be retrieved from ground-based, airborne and satellite measurements. However, due to the scattering and re-absorption effects inside the leaves and canopy, SIF measured at the canopy level is only a small part of the total SIF emission at the photosystem level. Therefore, a downscaling mechanism of SIF from the canopy level to the photosystem level is important for better understanding the relationship between SIF and the vegetation gross primary production (GPP). In this study, firstly, we analyzed the canopy scattering effects using a simple parameterization model based on the spectral invariant theory. The probability for SIF photons to escape from the canopy was found to be related to the anisotropic spectral reflectance, canopy interception of the upward solar radiation, and leaf absorption. An empirical approach based on a Random Forest (RF) regression algorithm was applied to downscale SIF constrained by the red, red-edge and far-red anisotropic reflectance. The RF was trained using simulations conducted with the Soil Canopy Observation, Photochemistry and Energy fluxes (SCOPE) model. The performance of the SIF downscaling method was evaluated with SCOPE and Discrete Anisotropic Radiative Transfer (DART) model simulations, ground measurements and airborne data. Results show that estimated SIF at the photosystem level matches well with simulated reference data, and the relationship between SIF and photosynthetically active radiation absorbed by chlorophyll is improved by SIF downscaling. This finding in combination with other evaluation criteria suggests the downscaling of canopy SIF as an efficient strategy to normalize species dependent effects of canopy structure and varying solar-view geometries. Based on our results for the SIF-APAR relationship, we expect that such normalization approaches can be helpful to improve estimates of photosynthesis using remote sensing measurements of SIF.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Remote Sensing of Environment, Volume 219〈/p〉 〈p〉Author(s): Nan Chen, Wei Li, Charles Gatebe, Tomonori Tanikawa, Masahiro Hori, Rigen Shimada, Teruo Aoki, Knut Stamnes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cloud detection and screening constitute critically important first steps required to derive many satellite data products. Traditional threshold-based cloud mask algorithms require a complicated design process and fine tuning for each sensor, and they have difficulties over areas partially covered with snow/ice. Exploiting advances in machine learning techniques and radiative transfer modeling of coupled environmental systems, we have developed a new, threshold-free cloud mask algorithm based on a neural network classifier driven by extensive radiative transfer simulations. Statistical validation results obtained by using collocated CALIOP and MODIS data show that its performance is consistent over different ecosystems and significantly better than the MODIS Cloud Mask (MOD35 C6) during the winter seasons over snow-covered areas in the mid-latitudes. Simulations using a reduced number of satellite channels also show satisfactory results, indicating its flexibility to be configured for different sensors. Compared to threshold-based methods and previous machine-learning approaches, this new cloud mask (i) does not rely on thresholds, (ii) needs fewer satellite channels, (iii) has superior performance during winter seasons in mid-latitude areas, and (iv) can easily be applied to different sensors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Remote Sensing of Environment, Volume 218〈/p〉 〈p〉Author(s): Xiaoping Wang, Fei Zhang, Hsiang-te Kung, Verner Carl Johnson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study aimed to improve the potential of Analytical Spectral Devices (ASD) hyperspectral and Landsat Operational Land Imager (OLI) data in predicting soil organic matter content (SOMC) in the bare topsoil of the Ebinur Lake Wetland National Nature Reserve (ELWNNR) in northwest China. The results indicated that the correlation of coefficients (R) between SOMCs and hyperspectral data processed by fractional derivative were significant at the 0.01 level; the number of wave bands increased initially and then decreased when the order increased. The correlation of coefficient peak appeared at the 1.2 order with a value of 0.52. The correlation of coefficients (R) between SOMCs and the optimal remote sensing indexes (the ratio index, RI; difference index, DI; and the normalized difference index, NDI) of peaked at the 1.2 order, with correlation of coefficients (R) values of 0.81, 0.86 and 0.82, respectively. Six SOMC estimation models were created by means of a single band and optimal remote sensing indexes using Gray Relational Analysis-BP Neural Network (GRA-BPNN). This study found that the optimal model was a 1.2 order derivative model, where the lowest root mean square error (RMSE) was 3.26 g/kg, the highest was 0.92, and the residual prediction deviation (RPD) was 2.26. To complete the high accuracy retrieval of SOMCs, based on Landsat OLI operational land images data, more ‘hidden’ information from the Landsat OLI images were obtained by employing the subsection of spectral band method and the fractional derivative algorithm. Accuracy of the SOMC map was attained by the optimal model of the ground hyperspectral data and the Landsat OLI data, which had low RMSE values of 4.21 g/kg and 4.16 g/kg, respectively. Therefore, we conclude that the SOMC can be estimated and retrieved using a fractional derivative algorithm, the subsection of spectral band method, and the optimal remote sensing index.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Transport Geography, Volume 72〈/p〉 〈p〉Author(s): Mengya Li, Mei-Po Kwan, Fahui Wang, Jun Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Commuting is an essential part of urban life. Long commutes have negative impacts on individuals and society, such as stress, loss of productivity, traffic congestion and air pollution. However, researchers often face the challenge of lack of data such as commute distance, duration, departure/arrival time, and origins/destinations in countries such as China. This study uses points of interest (POIs) to estimate employment locations, and implements a gravity-based model to estimate interzonal commuting patterns in central Shanghai, China. The results reveal a “busy corridor” in the west of the central city, especially during the morning peak hours. This pattern corresponds well with reported real-time traffic conditions in Shanghai. Our methodology offers a promising alternative for studying commuting patterns when such data are limited.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Transport Geography, Volume 72〈/p〉 〈p〉Author(s): Gaspar Mora-Navarro, Carmen Femenia-Ribera, Jose Martinez-Llario, Enrique Antequera-Terroso〈/p〉

Description: 〈p〉Publication date: Available online 21 March 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Transport Geography〈/p〉 〈p〉Author(s): Adeline Heitz, Laetitia Dablanc, Jerry Olsson, Ivan Sanchez-Diaz, Johan Woxenius〈/p〉 〈div xml:lang="fr"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In recent years, the location of logistics facilities, in particular with regard to “logistics sprawl,” has emerged as a topic in the literature that is, a process of spatial decentralisation of logistics facilities in large metropolitan areas. The aim of this paper is to look at logistics sprawl patterns in the Gothenburg metropolitan area, in the south-west of Sweden. Looking at a medium-size monocentric urban region that is also a major port gateway for the country, this study provides novel elements in the study of locational patterns of freight facilities in metropolitan areas. It also provides an opportunity to identify the role of freight in planning, land use and zoning policies. A literature review is carried out on the issues of freight and logistics facilities locational patterns. A quantitative analysis is proposed, using data from Swedish statistics about the number of establishments with a NACE code related to logistics, as well as an original method providing a “cleaned” and more comprehensive dataset. We look at data at two different scales, one metropolitan and one regional, for years 2000 and 2014, as to enable a comparative and diachronical analysis. Logistics sprawl is measured by the average distance of warehouses to their common centre of gravity. Finally, interviews with transport and logistics providers as well as real estate investors and public agencies in the region, add qualitative information on the relative importance of different location factors related to logistics facilities and the issues raised. Logistics sprawl in Gothenburg occurs in specific ways, and differently at the two geographical levels of analysis.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Applied Earth Observation and Geoinformation, Volume 75〈/p〉 〈p〉Author(s): Grigorijs Goldbergs, Stefan W. Maier, Shaun R. Levick, Andrew Edwards〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Obtaining reliable measures of tree canopy height across large areas is a central element of forest inventory and carbon accounting. Recent years have seen an increased emphasis on the use of active sensors like Radar and airborne LiDAR (light detection and scanning) systems to estimate various 3D characteristics of canopy and crown structure that can be used as predictors of biomass. However, airborne LiDAR data are expensive to acquire, and not often readily available across large remote landscapes. In this study, we evaluated the potential of stereo imagery from commercially available Very High Resolution (VHR) satellites as an alternative for estimating canopy height variables in Australian tropical savannas, using a semi-global dense matching (SGM) image-based technique. We assessed and compared the completeness and vertical accuracy of extracted canopy height models (CHMs) from GeoEye 1 and WorldView 1 VHR satellite stereo pairs and summarised the factors influencing image matching effectiveness and quality.〈/p〉 〈p〉Our results showed that stereo dense matching using the SGM technique severely underestimates tree presence and canopy height. The highest tree detection rates were achieved by using the near-infrared (NIR) band of GE1 (8–9%). WV1-GE1 cross-satellite (mixed) models did not improve the quality of extracted canopy heights. We consider these poor detection rates and height retrievals to result from: i) the clumping crown structure of the dominant Eucalyptus spp.; ii) their vertically oriented leaves (affecting the bidirectional reflectance distribution function); iii) image band radiometry and iv) wind induced crown movement affecting stereo-pair point matching. Our detailed analyses suggest that current commercially available VHR satellite data (0.5 m resolution) are not well suited to estimating canopy height variables, and therefore above ground biomass (AGB), in Eucalyptus dominated north Australian tropical savanna woodlands.〈/p〉 〈/div〉

Description: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 International Journal of Applied Earth Observation and Geoinformation, Volume 75〈/p〉 〈p〉Author(s): Hassan Awada, Giuseppe Ciraolo, Antonino Maltese, Giuseppe Provenzano, Miguel Angel Moreno Hidalgo, Juan Ignacio Còrcoles〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Remote sensing techniques allow monitoring the Earth surface and acquiring worthwhile information that can be used efficiently in agro-hydrological systems. Satellite images associated to computational models represent reliable resources to estimate actual evapotranspiration fluxes, 〈em〉ET〈/em〉〈sub〉a〈/sub〉, based on surface energy balance. The knowledge of 〈em〉ET〈/em〉〈sub〉a〈/sub〉 and its spatial distribution is crucial for a broad range of applications at different scales, from fields to large irrigation districts. In single plots and/or in irrigation districts, linking water volumes delivered to the plots with the estimations of remote sensed 〈em〉ET〈/em〉〈sub〉a〈/sub〉 can have a great potential to develop new cost-effective indicators of irrigation performance, as well as to increase water use efficiency. With the aim to assess the irrigation system performance and the opportunities to save irrigation water resources at the “SAT Llano Verde” district in Albacete, Castilla-La Mancha (Spain), the Surface Energy Balance Algorithm for Land (SEBAL) was applied on cloud-free Landsat 5 Thematic Mapper (TM) images, processed by cubic convolution resampling method, for three irrigation seasons (May to September 2006, 2007 and 2008). The model allowed quantifying instantaneous, daily, monthly and seasonal 〈em〉ET〈/em〉〈sub〉a〈/sub〉 over the irrigation district. The comparison between monthly irrigation volumes distributed by each hydrant and the corresponding spatially averaged 〈em〉ET〈/em〉〈sub〉a〈/sub〉, obtained by assuming an overall efficiency of irrigation network equal to 85%, allowed the assessment of the irrigation system performance for the area served by each hydrant, as well as for the whole irrigation district. It was observed that in all the investigated years, irrigation volumes applied monthly by farmers resulted generally higher than the corresponding evapotranspiration fluxes retrieved by SEBAL, with the exception of May, in which abundant rainfall occurred. When considering the entire irrigation seasons, it was demonstrated that a considerable amount of water could have been saved in the district, respectively equal to 26.2, 28.0 and 16.4% of the total water consumption evaluated in the three years.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Transportation Research Part F: Traffic Psychology and Behaviour, Volume 60〈/p〉 〈p〉Author(s): J. Harvey, W. Guo, S. Edwards〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The number of older people, especially those over 85, is set to increase right across the developed world, and with it their needs for mobility and transport in societies with growing dependence on technology. Whilst technology has the potential to deliver significant benefits to older people, enabling greater mobility and independence, it may also leave them unable or unwilling to engage with it, risking loss of independence.〈/p〉 〈p〉The aims of this paper are to consider what needs to change to enable greater numbers of older travellers to access transport technologies and what are the key barriers to engaging with new and emerging technologies for older people. Thus, the paper looks to extend the knowledge of how older people engage with technology in relation to their mobility and travelling.〈/p〉 〈p〉A thematic content analysis of interviews with 32 older people and 4 experts yielded findings relating to technology use, examples of good design, and characteristics of older people’s interactions with technology.〈/p〉 〈p〉The recommendations relate to the two core research aims, including ergonomics and design, the need for security and trust, the traveller controlling the technology, the importance of user-centered design and the need for personalised and bespoke travelling arrangements for older travellers.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 2 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Transportation Research Part A: Policy and Practice〈/p〉 〈p〉Author(s): José Holguín-Veras, Johanna Amaya Leal, Iván Sánchez-Diaz, Michael Browne, Jeffrey Wojtowicz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The first in a series of two, this paper conducts a review of the public-sector initiatives that could be used to improve freight activity in metropolitan areas; collects data about initiatives that have been implemented and their performance; and produces a ranking of suggested initiatives. The review of public-sector initiatives is based on a comprehensive analysis of their performance, which cataloged the initiatives into seven major groups, 15 subgroups, and 48 unique initiatives. The initiatives covered in this paper include: Infrastructure Management; Parking/Loading Areas Management; Vehicle-Related Strategies; and Traffic Management. The characterization of the state of the practice and the performance of the initiatives was based on a survey that collected data from 32 countries and 56 cities throughout the world. The third component of the work is a ranking of suggested initiatives based on the performance data collected by the survey. The paper ends with a discussion of chief findings.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Shi Qi, Jinzhu Ma, Xinying Ling, Qi Feng, Jianhua He, Heping Shu, Bing Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the southwestern Tengger desert in northwestern China, nitrate circulation processes in the unsaturated zone and associated driving factors were studied using water chemistry and stable isotope techniques. At unvegetated sand sites, NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 content increases from the south to north in the desert. Additionally, a negative correlation (R〈sup〉2〈/sup〉 = 0.90, P 〈 0.005) was evident between the stability of soil NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 and elevation, suggesting that NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 storage in soil is significantly influenced by precipitation and temperature. And a significant positive correlation between mNO〈sub〉2〈/sub〉〈sup〉−〈/sup〉/Cl〈sup〉−〈/sup〉 in unsaturated zone and elevation (R〈sup〉2〈/sup〉 = 0.50, P 〈 0.0001), indicating both nitrification and denitrification are strongly in the south of desert, however, the nitrification plays a dominant role in the north of desert. Isotopic analyses (δ〈sup〉15〈/sup〉N-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉, δ〈sup〉18〈/sup〉O-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉, and δ〈sup〉18〈/sup〉O-H〈sub〉2〈/sub〉O, δ〈sup〉2〈/sup〉H-H〈sub〉2〈/sub〉O) of soil pore-water showed that the two dominant NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 sources were the mixing of atmospheric deposition and soil nitrification, and that the NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 circulation at the vegetated sand sites was affected by vegetation and animals. Additionally, local environmental conditions lead to complex driving factors, such as the abiotic process of ammonia volatilization of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 circulation, which resulted in the 〈sup〉15〈/sup〉N enrichment and 〈sup〉18〈/sup〉O depletion of residual nitrate in the unsaturated zone of one of the soil profiles. Denitrification was noted in the deep unsaturated zone of two profiles, indicating that the N loss resulted from abiotic versus biotic processes. Analyses of the stable isotope results and the distribution characteristics of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 and Cl〈sup〉−〈/sup〉 suggests leaching of soil NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 as a result of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 in unsaturated zone poses a potential threat to groundwater quality in Dengmaying region. This study suggests that NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 circulation in the unsaturated zone responds to climate characteristics in the desert ecosystem, and to provide useful information for the protection of groundwater quality in arid desert regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Estela Luna, Claire Jouany, Carmen Castañeda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In arid and semiarid environments, saline wetlands are both high-value habitats threatened by landscape transformations, and a constraint to agricultural production. There is a lack of knowledge about nutrients distribution in intermittently flooded environments subjected to soil and water salinity. The aim of this work was to characterize soil and plant nutrient status along soil transects at the interface between agricultural land and saline wetlands. These aspects were studied in Guallar and Gallocanta, two Ramsar saline wetlands in NE Spain that represent arid and semiarid conditions, respectively. Soils were characterized for nitrogen (N) and phosphorous (P) status; crop and natural vegetation nutrient status was measured with P Nutrition Index (PNI) and Nitrogen Nutrition Index (NNI). Soil salinity (EC1:5) increases towards the halophyte areas, reaching 5.4 dS m〈sup〉−1〈/sup〉 in Guallar and 3.7 dS m〈sup〉−1〈/sup〉 in Gallocanta. On average, the soils are loams or sandy loams. Carbonate-rich soils are common (39% mean calcium carbonate equivalent) and some soils in Guallar have a high gypsum content (up to 72%). The soils have a low to moderate cation exchange capacity regardless of soil salinity, with a maximum of 14 cmol〈sup〉+〈/sup〉 kg〈sup〉−1〈/sup〉 in the soil with the highest organic matter content (3.8%). Overall, cereal soils show total P and N contents within the normal range for agricultural soils, although the available P is above the requirements for cereals, up to 67 mg kg〈sup〉−1〈/sup〉. The difference in soil nutrients between cropped and halophyte land is more noticeable when it comes to total and available P content than for N levels. The relatively high nutrient content in some halophyte soils and the total and available P gradients along the soil transects, reflect downslope nutrient movement towards the lake. Halophyte soils can accumulate between 11% and 71% of the available P found in cropped soils. No relationship was found between the soil nutrient content and that of plants, nor between these two parameters and soil salinity. NNI and PNI indicate non-limiting nutrient status for cereals grown in Gallocanta and nutrient limitation in Guallar, probably related to the high gypsum content, and/or soil salinity. Studying the plant available nutrient content in arid and saline soils, at the interface between halophytes and crops, is crucial for improving land management strategies and reconciling production and conservation in protected saline habitats.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Advances in Water Resources, Volume 122〈/p〉 〈p〉Author(s): N. Seigneur, V. Lagneau, J. Corvisier, A. Dauzères〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Most reactive transport codes and algorithms decouple the flow from the reactive transport calculations. In some cases, geochemical reactions lead to significant modifications of porosity or water-content, which can have an impact on the flow. The flow problem is based on the continuity equation and is described in terms of pressure. However, most reactive transport codes do not model the pressure-evolution through mineral reactions. The aim of this study is to recouple the reactive transport and the flow, by providing an accurate description of the evolution of both the porosity and the water in the reactive system. We discuss a formulation of the geochemical solver, based on a mole-conservation, which allows an accurate computation of the volume and masses of all phases. This allows for a water and pore volume computation at the scale of the REV which can impact the fluid-pressure, hence the flow. Additionally, solving the geochemical equilibrium in terms of moles instead of concentrations is more accurate for problems involving important mineral reactions. Finally, this method is suited to saturated, unsaturated and two-phase flow. This method is easy to implement and can be used in different reactive transport simulators, regardless of their numerical approaches. We also test the numerical efficiency of this approach and apply it to fully-coupled problems involving variable porosity, variable saturation, water production/consumption.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 133〈/p〉 〈p〉Author(s): Ian Grooms, William Kleiber〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A depth-independent isotropic Gent-McWilliams (GM) transport parameter 〈em〉κ〈/em〉 is diagnosed from an idealized eddy-resolving primitive equation simulation. The optimal depth-independent isotropic GM parameterization is only able to model less than 50% of the diagnosed total tendency of temperature induced by unresolved mesoscale eddies. A spatio-temporal stochastic model of the GM parameter is developed based on the diagnosed values; the graphical lasso is used to estimate the spatial correlation structure. The stochastic model is used as a stochastic parameterization in low-resolution model simulations. The low-resolution stochastic simulation does a poor job of reproducing the temporal mean of large-scale temperature. Deterministic GM parameterizations and multiplicative stochastic GM parameterizations with unrealistic structure result in significantly more-accurate large-scale temperature in the low-resolution simulations. These results suggest that either the depth-independence or the isotropy of the GM parameterization are unrealistic as models of the eddy tracer transport, or that a stochastic GM parameterization should include an additive component.〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 327〈/p〉 〈p〉Author(s): Qunsheng Fang, Chuan Tang, Zhihe Chen, Shuaiyong Wang, Tao Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The factors affecting debris flow runout volume changed considerably in the Wenchuan earthquake area. The main characteristic parameters for calculating the debris flow runout volume, namely, channelized landslide dam volume are first used to establish empirical models. A new empirical statistical model is established by applying a multivariate regression analysis to the runout volumes of dam-break and non-dam-break debris flows. Additionally, FLO-2D is used to simulate the debris flow runout volumes under the non-dam-breaking and dam-breaking scenarios. When the rainfall frequency is P = 1%, the predicted runout volumes in the Huaxi gully are 24.48 × 10〈sup〉4〈/sup〉 m〈sup〉3〈/sup〉 under the non-dam-breaking scenario and 43.41 × 10〈sup〉4〈/sup〉 m〈sup〉3〈/sup〉 under the dam-breaking scenario. The runout volume in the dam-breaking scenario is 6.07 × 10〈sup〉4〈/sup〉 m〈sup〉3〈/sup〉 more than 1.77 times that in the non-dam-breaking scenario. The predicted runout range of the dam-breaking scenario is 1.16 times that of the non-dam-breaking scenario. The predicted alluvial fan areas and average accumulation depths in the dam-breaking scenario are larger than those in the non-dam-breaking scenario. The predicted runout volume of the dam-breaking scenario is 5.58 × 10〈sup〉4〈/sup〉 m〈sup〉3〈/sup〉 which is less than the actual surveyed volume (48.99 × 10〈sup〉4〈/sup〉 m〈sup〉3〈/sup〉). The relative error and accuracy of the numerical simulation results are −11.39 and 88.61% for the dam-breaking scenario. The new runout volume model was developed in catchments with abundant loose materials in the Wenchuan earthquake area and can thus be applied to debris flow gullies in meizoseismal areas with newly fractured regolith and abundant loose material to estimate runout volumes. The results of this study will help authorities select safe sites for future rehabilitation and relocation projects and can also be used as an important basis for debris flow risk management.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169555X18304379-ga1.jpg" width="103" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 327〈/p〉 〈p〉Author(s): I.M. Bollati, A. Masseroli, G. Mortara, M. Pelfini, L. Trombino〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Denudation processes affecting mountain slopes may vary according to different factors (e.g., lithology and structural setting of bedrock, climate, relief features), which may be very diverse at the local scale. Gully complex systems, characterised by morphological features similar to those developing in other climate contexts (i.e., 〈em〉pseudo-badlands〈/em〉) are also becoming common at higher altitudes and latitudes. The selected study cases of Gran Gorgia (Susa Valley) and Saint Nicolas (Aosta Valley), in the Western Italian Alps, are sites of geomorphological interest as they are specifically relevant for their scientific features. The aims of this work are (i) reconstructing the morphometric evolution of gully systems and vegetation colonisation time by means of multitemporal spatial analysis on surface morphological changes under water erosion; (ii) reconstructing in detail, through dendrogeomorphological analysis, the progressive spatial surface denudation and changes in erosion rates, by analysing trees and exposed roots and using different indicators (i.e., compression wood, traumatic resin ducts); (iii) obtaining data on successive aggradation/degradation episodes along slopes surrounding such hotspots through geopedological investigations; and (iv) identifying which control factors exert a predominant role on denudation patterns in such contexts. Multidisciplinary analyses regarding the study sites allowed for detailing of erosional history of the studied slopes detecting the prevailing drivers of their evolution. According to the results and considering the common climate and bedrock conditions, the structural background seems to have more influence on slope evolution at the Saint Nicolas site, while superficial geomorphic processes seem to be more relevant at the Gran Gorgia site. Because the sites have already been recognised as part of geoheritage by local authorities, the data obtained in the present research on their genesis, evolution, and local drivers affecting the rates of denudation (i.e., scientific relevance of the site) suggests that description of the sites for dissemination purposes should include links to the entire slope history.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 216〈/p〉 〈p〉Author(s): Colin J. McNeece, Johannes Lützenkirchen, Marc A. Hesse〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of acidity and salinity on solute transport in porous media are important to a diverse range of fields from seawater intrusion to nuclear waste storage. Recent transport experiments in quartz sand show the difficulty in capturing the coupling of acidity and salinity under acidic conditions for this system. Here we study the ability of different surface complexation models to capture this coupling, through an analysis of the reactive transport equations in the limit of no diffusion. This chromatographic analysis leads to a graphical representation of the full set of solutions in the phase plane, thus allowing a comprehensive comparison of the transport behavior arising from different SCMs. The analysis shows that the predicted coupling is improved by including amphoteric behavior of the quartz surface. The inclusion of a secondary proton sorption reaction increases the magnitude of surface charge under acidic conditions strengthening the acidity-salinity coupling. This suggests that even though the overall surface is negative above the point of zero charge, positively charged sites play an important role in the reactive transport of acidity and salinity.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Bowen Li, Chunpeng Zhang, Yan Li, Chunyu Wen, Jun Dong, Meng Yao, Liming Ren〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent laboratory studies have shown the injection of colloidal Mg(OH)〈sub〉2〈/sub〉 could provide an effective and low cost alternative as a long term pH buffering system. In this study, Mg(OH)〈sub〉2〈/sub〉 was modified by Tween 80 and SDS and the modified suspension had the properties of high stability, small particle size (the average particle diameter 〈em〉D〈/em〉〈sub〉〈em〉50〈/em〉〈/sub〉 was smaller than 1 μm) and negative charge (zeta potential = −14.26 mV at pH = 10.54). All of these properties demonstrated that colloidal Mg(OH)〈sub〉2〈/sub〉 may have satisfactory transport performance in porous media. However, colloidal Mg(OH)〈sub〉2〈/sub〉 is heterogeneous colloids with a high concentration, the transport performance in porous media is significantly different from homogeneous colloids, and the model simulation is relatively complex. To solve these problems, method of calculus combined with colloid filtration theory (CFT), T-E equation and modified Maxwell theory was used to simulate the transport performance of high concentration of Mg(OH)〈sub〉2〈/sub〉 colloids. Results indicated that the observed experimental results matched well with the model simulations. Hydrodynamic force, DLVO attractive force and colloid diffusion are the major factors controlling the migration of colloidal Mg(OH)〈sub〉2〈/sub〉 in porous media and could quantitatively describe the influence of injection velocity, porous media size and ionic strength on colloidal Mg(OH)〈sub〉2〈/sub〉 transport properties by model calculation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 217〈/p〉 〈p〉Author(s): Allen M. Shapiro, Rebecca J. Brenneis〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Contaminants diffusing from fractures into the immobile porosity of the rock matrix are subject to prolonged residence times. Organic contaminants can adsorb onto organic carbonaceous materials in the matrix extending contaminant retention. An investigation of spatial variability of the fraction of organic carbon (〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉) is conducted on samples of rock core from seven closely spaced boreholes in a mudstone aquifer contaminated with trichloroethene (TCE). A total of 378 samples were analyzed at depths between 14 and 36 m below land surface. Mudstone units associated with deep water deposition have the largest 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉, with a maximum value of 0.0396, and units associated with shallow water deposition have the smallest 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉. Even though 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉 correlates with depositional conditions, 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉 still varies over more than an order of magnitude in continuous mudstone layers between boreholes, and there is large variability in 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉 over short distances perpendicular to bedding. Simulations of diffusion and linear equilibrium adsorption of TCE using spatially variable 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉 in the rock matrix show order of magnitude variability in the adsorbed TCE over short distances in the matrix and residence times extending to hundreds of years following remediation in adjacent fractures. Simulations using average values of 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉 do not capture the range of TCE mass that can be retained in a rock matrix characterized by spatially variable 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉. Bounds on TCE mass within the rock matrix can be obtained by simulations with spatially uniform values of 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉 equal to the maximum and minimum values of 〈em〉f〈/em〉〈sub〉〈em〉oc〈/em〉〈/sub〉 for a given mudstone unit.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Paul B. Hatzinger, James F. Begley, David R. Lippincott, Adria Bodour, Rose Forbes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉1,2-Dibromoethane (ethylene dibromide; EDB) is a probable human carcinogen that was historically added to leaded gasoline as a scavenger to prevent the build-up of lead oxide deposits in engines. Studies indicate that EDB is present at thousands of past fuel spill sites above its stringent EPA Maximum Contaminant Level (MCL) of 0.05 μg/L. There are currently no proven in situ options to enhance EDB degradation in groundwater to meet this requirement. Based on successful laboratory studies showing that ethane can be used as a primary substrate to stimulate the aerobic, cometabolic biodegradation of EDB to 〈0.015 μg/L (Hatzinger et al., 2015), a groundwater recirculation system was installed at the FS-12 EDB plume on Joint Base Cape Cod (JBCC), MA to facilitate in situ treatment. Groundwater was taken from an existing extraction well, amended with ethane, oxygen, and inorganic nutrients and then recharged into the aquifer upgradient of the extraction well creating an in situ reactive zone. The concentrations of EDB, ethane, oxygen, and anions in groundwater were measured with time in a series of nested monitoring wells installed between the extraction and injection well. EDB concentrations in the six monitoring wells that were hydraulically well-connected to the pumping system declined from ~ 0.3 μg/L (the average concentration in the recirculation cell after 3 months of operation without amendment addition) to 〈0.02 μg/L during the 4-month amendment period, meeting both the federal MCL and the more stringent Massachusetts MCL (0.02 μg/L). The data indicate that cometabolic treatment is a promising in situ technology for EDB, and that low regulatory levels can be achieved with this biological approach.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): María Laura Vázquez Juiz, Diego Soto Gómez, Paula Pérez Rodríguez, Marcos Paradelo, José Eugenio López Periago〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tunable Resistive Pulse Sensing, TRPS, is an emerging technique used in quantification and measuring the size (particle-by-particle) of viruses, exosomes and engineered colloidal spheres in biological fluids. We study the features of TRPS to enhance size characterization and quantification of submicron-sized microplastics, also called plastic microparticles, MP, in freshwater environments. We report alterations on the detection of the resistive pulses in the TRPS caused by humic acids, HA, during the size measurement of polystyrene microspheres used as MP surrogate. We discuss the alteration of the electric field in the measuring channel of the TRPS apparatus induced by the passage of HA. TRPS is a fast and precise technique for counting and size determination of MP but needs the evaluation of the influence of the organic matter on the current blockades. We show that statistical clustering models of the magnitude distribution of the resistive pulses can help to detect and quantify changes in the pulse size distributions induced by flocculation of humic acids. Conclusions of this study indicate that TRPS can be a valuable tool to improve the knowledge of the MP fate in surface waters, in the vadose zone and groundwater.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169772218301554-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 219〈/p〉 〈p〉Author(s): Brianne N. Hicknell, Kevin G. Mumford, Bernard H. Kueper〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In situ thermal treatment (ISTT) technologies have been applied at sites impacted by non-aqueous phase liquids (NAPLs). There is a need to establish expectations for the treatment of semi-volatile NAPLs, including those consisting primarily of polycyclic aromatic hydrocarbons (PAHs), and the potential benefits and limitations of partial NAPL removal. A series of laboratory experiments was conducted to investigate NAPL removal and soil concentrations during the heating of creosote-impacted sand, as well as aqueous concentrations during post-heating dissolution. The results showed co-boiling near the water boiling temperature due to the low volatility of most creosote components, with limited decreases in NAPL saturation (from 30% to 21% of the pore space). Decreases in soil concentration were more substantial than decreases in NAPL saturation (by a factor of 2–180), with greater removal for higher-volatility components at higher treatment temperatures. Results of the dissolution experiments showed mixed results, with decreases in the aqueous concentrations for 12 of 15 components, but increases in aqueous concentrations for phenanthrene, fluoranthene and pyrene after heating to 205 °C or 320 °C. Overall, the results illustrate the utility of bench-scale treatability tests in helping to establish ISTT goals and expectations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Agustín Spaltro, Matías Pila, Sandra Simonetti, Silvia Álvarez-Torrellas, Juan García Rodríguez, Danila Ruiz, Andres Díaz Compañy, Alfredo Juan, Patricia Allegretti〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, commercial activated carbons (GAB and CBP) were successfully used for the removal of two phenoxy acetic class-herbicides, 4-chloro-2-methyl phenoxy acetic acid and 2.4-dichlorophenoxy acetic acid (MCPA and 2.4-D) from aqueous solution. The adsorbent materials were characterized, and their equilibrium adsorption capacity was evaluated. The results suggest that the microporous properties of GAB activated carbon enhanced the adsorption capacity, in comparison to CBP carbon. Thus, the increasing in the ionic strength favored the adsorption removal of both pesticides, indicating that electrostatic interactions between the pollutant and the adsorbate surface are governing the adsorption mechanism, but increasing pH values decreased adsorption capacity. Experimental data for equilibrium was analyzed by two models: Langmuir and Freundlich. Finally, computational simulation studies were used to explore both the geometry and energy of the pesticides adsorption.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Gláucia da P. Lima, Jessica R. Meyer, Kamini Khosla, Kari E. Dunfield, Beth L. Parker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dissolved phase contaminants, transported by diffusion into the low permeability matrix of fractured sedimentary rock, pose a challenge to groundwater cleanup efforts because this stored mass may persist even when the upgradient source zone is removed. In this context, if contaminant biodegradation takes place within the low permeability matrix, plume persistence may be substantially reduced. Therefore, it is important to characterize microbial communities within the low permeability, rock matrix pores, instead of only from groundwater samples, which represent biomass from fast flowing fractures. This research relies on depth-discrete data from both core and groundwater samples collected from two locations representing a mid-plume and plume front condition within an aged, mixed organic contaminant plume in a sedimentary rock aquifer. Results from multiple analyte measurements on rock and groundwater indicate that biodegradation in the lower permeability matrix of fractured sedimentary rocks and the microbial consortia is spatially variable due to differences in hydrochemistry, redox conditions, and contaminant concentrations. Dechlorinating microorganisms were detected in the sandstone matrix at both locations, but the detected microbial diversity calculated with PCR-DGGE was significantly higher in samples collected from the core located closer to the source zone, where contaminant concentrations are higher and contaminant compositions more diverse, compared to samples from the plume front location.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169772218301712-ga1.jpg" width="369" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 216〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 219〈/p〉 〈p〉Author(s): N. Sihota, B. McAlexander, M. Lyverse, K.U. Mayer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The changing landscape of fuel consumption related, in part, to increased engine efficiency and the inexpensive supply of natural gas, has led to the closure of multiple refineries. As the operational lifetime of many refineries exceeds 100 years, historical releases of oil and refined products is common. To evaluate remediation and rehabilitation options, there is a need to understand the rate and distribution of natural hydrocarbon mass losses across these large properties. Here, surficial CO〈sub〉2〈/sub〉 flux measurements were used to evaluate naturally occurring hydrocarbon mass losses at a large-scale former refinery that has been closed since 1982. Natural source zone depletion (NSZD) rates over a five-year period (2012–2016) were derived from surficial CO〈sub〉2〈/sub〉 efflux measurements on a high-resolution grid (N 〉 80). Results demonstrate substantial variations of mass loss rates across the site. Average site-wide mass loss rates ranged from 1.1–5.4 g TPH m〈sup〉−2〈/sup〉 d〈sup〉−1〈/sup〉 as C〈sub〉10〈/sub〉H〈sub〉22〈/sub〉 with a multi-year average of 4.0 g TPH m〈sup〉−2〈/sup〉 d〈sup〉−1〈/sup〉 as decane (C〈sub〉10〈/sub〉H〈sub〉22〈/sub〉), consistent with observations at other sites. Statistical analysis demonstrated that the same average mass loss rates would have been obtained with fewer measurement locations (N = 20–30). Comparing NSZD rates to site metadata show CO〈sub〉2〈/sub〉 fluxes to be a reasonably good proxy for zones of subsurface hydrocarbon contamination – particularly with respect to vadose zone impacts. It is hypothesized that the observed decline of NSZD rates over the study period is related to rise of groundwater levels, leading to increased submergence of the smear zone. Overall, mass loss rates calculated from CO〈sub〉2〈/sub〉 fluxes show NSZD can result in substantial contaminant removal, which may rival that obtained from engineered remediation, under some conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 216〈/p〉 〈p〉Author(s): Naser Shokri, Masoud Montazeri Namin, Javad Farhoudi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉A three dimensional coupled numerical model has been developed for incompressible density-driven free surface and saturated porous media flows. For free surface, a time-averaged Navier-Stokes equation has been used whereas Darcy's law has been utilized in porous media flow. The algorithm has been based upon a staggered finite volume scheme on a Cartesian grid that solves the 3D non-hydrostatic density-dependent Darcy equation in one step and complete 3D Navier–Stokes equations in two major steps based on a projection method. The 3D system is decomposed into a series of 2D vertical plane sub-systems which have been solved individually by a direct matrix solver. An iteration procedure can be deployed to achieve the fully 3D implicitness of the solution where high density gradients or sharp variation of free surface elevation is present. An efficient, simple and stable algorithm has been proposed to track the free surface elevation in a Cartesian coordinate system within which the water surface position has not been restricted to a specific layer.〈/p〉 〈p〉The model has been validated using five test cases to simulate integrated transient free surface and porous media flows where fluid density effects as well as the water surface gradient have a considerable effect on the velocity field. Two of the examples involve modeling free surface flow (Wave Reflection test) and a phreatic line prediction (Cone of depression test). Two other test cases involve significant contrasts in fluid density including 3D density-driven flow in porous media and 3D lock exchange tests. The final test of a salinity interface involved a complicated scenario consisting of a density contrast in both saturated porous media and free surface flow, subjected to injection and pumping simulated simultaneously using an integrated domain. Close agreement between numerical results and experimental data demonstrates the capability of the model for the coupled simulation of 3D density-driven flow in both integrated free surface and saturated porous media including freshwater recharge, saltwater discharge, hydrodynamic dispersion and turbulence effects.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 217〈/p〉 〈p〉Author(s): Leyun Wang, Xilai Zheng, Feifei Tian, Jia Xin, Hui Nai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nitrogen (N) fertilizers have been extensively used to maintain soil fertility in intensively agricultural soils, creating serious environmental pollution. In this study, a 70-day incubation experiment was conducted to investigate the effects of different N fertilizers (urea, manure, straw) on N mineralization, soluble organic nitrogen (SON) dynamics and its leaching potential in typical agricultural soils of the Shandong Peninsula. The results showed that the addition of N fertilizers affected the SON pools and soil N mineralization in different ways owing to their various properties and interaction with soils. When comparing treatments, urea application was found to decrease SON content, whereas manure and straw addition increased the SON content after long-term incubation. Considering that SON content depended on a complicated formation process and consumption process, no direct link between SON content and N mineralization capacity was observed in different treatments. Additionally, we analyzed free amino acids (FAAs) in SON and found that FAA content was negatively correlated with N mineralization, except for the straw treatment. This suggested that FAAs were important substrates of N mineralization in soils. In addition, the composition of SON was determined by 3-dimensional excitation-emission matrix and ultraviolet-visible absorbance spectrophotometer after long-term incubation. The P〈sub〉III+V〈/sub〉/P〈sub〉I+II+IV〈/sub〉 ratio, SUVA〈sub〉254〈/sub〉, and A〈sub〉253〈/sub〉/A〈sub〉203〈/sub〉 ratio decreased after fertilizer application. This indicated that fertilizer addition decreased the SON humification degree and increased SON leaching. Therefore, SON should be taken into account when optimizing fertilization management and evaluating the risk of N leaching in groundwater systems.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169772218300858-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 219〈/p〉 〈p〉Author(s): Vagner Tebaldi de Queiroz, Mariane Martins Azevedo, Iana Pedro da Silva Quadros, Adilson Vidal Costa, Atanásio Alves do Amaral, Gleissy Mary Amaral Dino Alves dos Santos, Ronie Silva Juvanhol, Lucas Arthur de Almeida Telles, Alexandre Rosa dos Santos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The extensive use of pesticides in agricultural practices has been associated with human health problems and environmental contamination worldwide. Brazil is the largest consumer of pesticides in the world and Espírito Santo State stands out as the second Brazilian producer of coffee. However, there is no information about environmental impact of coffee producing at Itapemirim River Basin (IRB) region, Espírito Santo State, Brazil; hence a simple and quick method using open access softwares (AGROSCRE and ARAquá Web) to estimate surface entrainment and pesticide leaching potential was carried out. AGROSCRE evaluates the contamination risk of superficial and groundwater by Active Ingredients (AIs), using GOSS Method, GUS index and US EPA criteria, while ARAquá Web estimates AI concentrations in water resources, indicating their suitability based on water quality requirements for different uses. Regarding pesticides used in coffee plantations, there is 44.7% chance of surface water and 23.7% chance of groundwater contamination. Results showed that ametryne, cyproconazole, diuron, epoxiconazole, flutriafol, triadimenol and triazophos pose contamination risk to both surface water and groundwater in the IRB region. Of these, 10.5% of the total AIs are triazoles and fall under environmental classes II and III (Product Very/Dangerous to the Environment). The AIs ametryne, thiamethoxam, iprodione, flutriafol, triazophos, endosulfan, triadimenol, cyproconazole, diuron, pendimethalin, chlorpyrifos, copper II hydroxide, etion, epoxiconazole and paraquat dichloride, were found to be potentially toxic, presenting environmental concentrations ranging from 123.40 μg L〈sup〉-1〈/sup〉 to 0.14 μg L〈sup〉-1〈/sup〉, which are higher than the safety standard for potable water (0.1 μg L〈sup〉-1〈/sup〉). With respect to these AIs, chlorpyrifos, ethion and triazophos showed concentrations higher than EC〈sub〉50〈/sub〉 values for aquatic invertebrates and ametryne and diuron for algae. Thus, local residents and environment may be at high risk of pesticide exposure, when these AIs are used in coffee plantations next to surface water or groundwater.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169772217303121-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 216〈/p〉 〈p〉Author(s): Murugan Ramasamy, Christopher Power, Martin Mkandawire〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Remediation at former mining sites containing waste rock piles (WRPs) commonly involves the installation of a cover system over the waste rock to limit water and oxygen ingress and attenuate the impacts of acid mine drainage (AMD) to the environment. Cover systems containing high-density polyethylene (HDPE) liners have the attributes to be highly effective; however, their performance over the long-term is unknown. The objective of this study was to assess the long-term effectiveness of an ‘in-service’ HDPE-lined cover system for reducing AMD contamination at WRP sites. A numerical investigation of a former mining site containing a large WRP reclaimed with an HDPE cover is presented. A 3-D groundwater flow and contaminant transport model of the site was developed in FEFLOW to predict the spatial and temporal evolution of AMD over 100 years. Field parameters observed at 46 monitoring wells over a 5-year monitoring period (including hydraulic head, recharge, hydraulic conductivity and water quality) were used as key input and calibration parameters. The HDPE cover significantly reduced both water recharge to the waste rock (i.e., 512 to 50 mm/year) and AMD seepage to groundwater. Both the groundwater flow and contaminant transport (sulfate was used as an AMD tracer) components of the model were calibrated and verified to the observed field data, with strong correlations evident between observed and simulated hydraulic heads and sulfate concentrations, respectively. Long-term model predictions of AMD evolution indicated significant and continual reductions in sulfate concentrations over time at all well locations. Background concentration levels (25 mg/L) are expected to be reached within 40 years. This study has demonstrated that HDPE-lined cover systems can be highly effective in reducing AMD loading from WRPs and its impacts on the receiving environment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 219〈/p〉 〈p〉Author(s): Michael C. Brooks, A. Lynn Wood, Jaehyun Cho, Christine A.P. Williams, William Brandon, Michael D. Annable〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Source strength functions (SSF), defined as contaminant mass discharge or flux-averaged concentration from dense nonaqueous phase liquid (DNAPL) source zones as a function of time, provide a quantitative model of DNAPL source-zone behavior. Such information is useful for calibration of screening-level models to assist with site management decisions. We investigate the use of historic data collected during long-term monitoring (LTM) activities at a site in Rhode Island to predict the SSF based on temporal mass discharge measurements at a fixed location, as well as SSF estimation using mass discharge measurements at a fixed time from three spatially distributed control planes. Mass discharge based on LTM data decreased from ~300 g/day in 1996 to ~70 g/day in 2012 at a control plane downgradient of the suspected DNAPL source zone, and indicates an overall decline of ~80% in 16 years. These measurements were compared to current mass discharge measurements across three spatially distributed control planes. Results indicate that mass discharge increased in the downgradient direction, and was ~6 g/day, ~37 g/day, and ~400 g/day at near, intermediate, and far distances from the suspected source zone, respectively. This behavior was expected given the decreasing trend observed in the LTM data at a fixed location. These two data sets were compared using travel time as a means to plot the data sets on a common axis. The similarity between the two data sets gives greater confidence to the use of this combined data set for site-specific SSF estimation relative to either the sole use of LTM or spatially distributed data sets.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Noelia Muskus, Ronald W. Falta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A semi-analytical/numerical method for modeling matrix diffusion in heterogeneous and fractured groundwater systems is developed. This is a significant extension of the Falta and Wang (2017) method that only applied to diffusion in an aquitard of infinite thickness. The current solution allows for the low permeability matrix to be embedded within a numerical gridblock, having finite average thickness, a specified volume fraction and a specified interfacial area with the high permeability domain. The new formulation also allows for coupled parent-daughter decay reactions with multiple species that each have independent retardation factors, decay rates, and yield coefficients in both the high and low permeability parts of the system. The method uses a fitting function to approximate the transient concentration profile in the low permeability part of each gridblock so that the matrix diffusion flux into the high permeability part of the gridblock can be computed as a concentration dependent source-sink term. This approach is efficient because the only unknowns in each gridblock are the concentrations in the high permeability domain, so there is practically no increase in computational effort compared to a conventional transport simulation. The method is shown to compare favorably with an analytical solution for matrix diffusion in fractured media with parallel fractures, with an analytical solution for matrix diffusion with parent-daughter decay reactions, with laboratory experiments of matrix diffusion in a layered system, with a laboratory experiment involving lens shaped inclusions, and with fine grid numerical simulations of transport in highly heterogeneous systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): P. Jamin, S. Brouyère〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Classic estimates of groundwater fluxes are usually based on the application of Darcy's law, which can lead to large imprecisions in transient groundwater flow cases. There is a need for direct, in situ measurement techniques able to monitor time-variable groundwater fluxes. The investigation presented here demonstrates that the Finite Volume Point Dilution Method (FVPDM) is a promising technique for the continuous monitoring of groundwater fluxes. The experimental configuration consisted of monitoring transient groundwater fluxes generated by a multiple step pumping test, which was undertaken in the alluvial aquifer of the River Meuse, Liège (Belgium). Additionally, two FVPDM tests were simultaneously performed in two piezometers screened at two different depths in the alluvial aquifer. Tracer concentration changes during the FVPDM tests were interpreted as the consequences of Darcy flux changes in the alluvial aquifer, which was related to changes in the applied pumping rate. Piezometric levels were also monitored in piezometers located around the pumping well. The pumping test was interpreted using classical analytical solutions, and the FVPDM tests were interpreted using a new mathematical solution, which allows for calculating changes in Darcy fluxes based on the FVPDM tracer concentration evolution during transient groundwater flow conditions. The experiment demonstrated the FVPDM's ability to monitor, as well as be sensitive to changes in transient groundwater fluxes. The FVPDM interpretation also showed contrasting results between the upper part of the aquifer, which is made of loam and sand and slow groundwater flows prevail, and the lower part of the aquifer, which is made of gravels and pebbles and intense groundwater flows prevail.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 216〈/p〉 〈p〉Author(s): Jun Zhou, Xiaosi Su, Geng Cui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Groundwater reactive transport models that consider the coupling of hydraulic and biochemical processes are vital tools for predicting the fate of groundwater contaminants and effective groundwater management. The models involve a large number of parameters whose specification greatly affects the model performance. Thus model parameters calibration is crucial to its successful application. The Bayesian inference framework implemented by Markov chain Monte Carlo (MCMC) sampling provides a comprehensive framework to estimate the model parameters. However, its application is hampered by the large computational requirements caused by repeated evaluations of the model in MCMC sampling. This study develops an adaptive Kriging-based MCMC method to overcome the bottleneck of Bayesian inference by replacing the simulation model with a computationally inexpensive Kriging surrogate model. In the adaptive Kriging-based MCMC method, instead of constructing a globally accurate surrogate of the simulation model, we sequentially build a locally accurate surrogate with an iterative refinement to the high probability regions. The performance of the proposed method is demonstrated using a synthetic groundwater reactive transport model for describing sequential Kinetic degradation of Tetrachloroethene (PCE), whose hydraulic and biochemical parameters are jointly estimated. The results suggest that the adaptive Kriging-based MCMC method is able to achieve an accurate Bayesian inference with a hundredfold reduction in the computational cost compared to the conventional MCMC method.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 216〈/p〉 〈p〉Author(s): Andrea D'Aniello, Niels Hartog, Thomas Sweijen, Domenico Pianese〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Industrial use has led to the presence of liquid elemental mercury (Hg〈sup〉0〈/sup〉) worldwide in the subsurface as Dense NonAqueous Phase Liquid (DNAPL), resulting in long lasting sources of contamination, which cause harmful effects on human health and detrimental consequences on ecosystems. However, to date, insight into the infiltration behaviour of elemental mercury DNAPL is lacking. In this study, a two-stage flow container experiment of elemental mercury DNAPL infiltration into a variably water saturated stratified sand is described. During the first stage of the experiment, 16.3 ml of liquid Hg〈sup〉0〈/sup〉 infiltrated and distributed into an initially partially water saturated system. Afterwards, during the second stage of the experiment, consisting of the simulation of a “rain event” to assess whether the elemental mercury already infiltrated could be mobilized due to local increases in water saturation, a significant additional infiltration of 4.7 ml of liquid mercury occurred from the remaining DNAPL source. The experiment showed that, under conditions similar to those found in the field, Hg〈sup〉0〈/sup〉 DNAPL infiltration is likely to occur via fingers and is strongly controlled by porous medium structure and water saturation. Heterogeneities within the porous medium likely determined preferential pathways for liquid Hg〈sup〉0〈/sup〉 infiltration and distribution, as also suggested by dual gamma ray measurements. Overall, this study highlights that the infiltration behaviour of mercury DNAPL is strongly impacted by water saturation. In the field, this may result in a preferential infiltration of Hg〈sup〉0〈/sup〉 DNAPL in wetter areas or in its mobilization due to wetting during a rain event, as indicated by this study, or a groundwater table rise. This should be considered when assessing the likely distribution pathways of historic mercury DNAPL contamination as well as the remediation efforts.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Qianqian Zhang, Huiwei Wang, Long Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nitrate contamination in groundwater has become an environmental problem of widespread concern. In this study, we used environmental isotopes (δ〈sup〉15〈/sup〉N-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 and δ〈sup〉18〈/sup〉O-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉) and an isotope mixing model (SIAR) to identify the main sources of nitrate pollution, and factors controlling nitrate pollution, and to quantify the relative contributions of potential NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 sources in an over-exploited groundwater region, north China. The results showed that human activities had dramatically increased the mean concentration of groundwater NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 reaching 124.4 mg/L. In Hutuo River pluvial fan region, groundwater nitrate came from many kinds of pollution sources and the predominant sources were sewage and/or manure. Nitrification might be one of the most important nitrogen transformation processes and groundwater intensely exploited was a major inducing factor for the NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 pollution. The highest contribution of groundwater NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 was sewage and/or manure which the percent in the Hutuo River valley plain unit, upper pluvial fans of Hutuo River and central pluvial fans of Hutuo River was 54.9%, 55.0% and 61.8%, respectively, followed by soil N, NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉 in fertilizer and rain, NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 fertilizer, and NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 in precipitation. We suggested that the local government must strengthen the sewage treatment for the collection of domestic sewage, and must prohibit over-exploitation of groundwater in order to prevent NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 contamination of in groundwater.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Beiyi Xu, Guangcai Wang, Qiang Yang, Yan Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Shallow groundwater in alluvial plains is vulnerable to contamination due to infiltration of pollutants from anthropogenic activities. In the alluvial plain of the Yangtze River near Poyang Lake, a silicone monomer industrial park was found to discharge undisclosed amount of effluents containing high levels of hydrochloric acid and total dissolved solids into ponds and ditches that in turn, displayed characteristics of acidic water with high total dissolved solids. However, most shallow groundwater (〈em〉n〈/em〉 = 35, depth 5.5–22 m) collected from the alluvial aquifer downgradient of the industrial park contained low Cl〈sup〉−〈/sup〉 (〈 59 mg/L). Only 4 groundwater samples showed high Cl〈sup〉−〈/sup〉 (59–790 mg/L) with two containing superlative levels (449 mg/L and 790 mg/L) located within a 50 m distance from the polluted ponds and ditches. In addition to hydrochemical data, modeling was used to explain why a highly vulnerable alluvial aquifer was not more contaminated when subjected to such intense point source pollution and to estimate the effluent discharge. Flow and solute transport modeling suggests that a hydrological buffering mechanism resulting from a topography driven groundwater outflow along the boundary between the Pleistocene (Qpw) and the Holocene (Qhl) aquifers where the polluted ponds and ditches are fortuitously located has restricted acid infiltration, with only a few percent of the estimated acid discharge in the amount of 1700–4200 tons per year entering the aquifer. Our model results show that pumping from the upland Qpw aquifer breaks this hydrological buffering much more easily than pumping from the downgradient Qhl aquifer, suggesting the vulnerability of this buffering mechanism thus compromising groundwater utilization in the future.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 217〈/p〉 〈p〉Author(s): Malcolm S. Field, William E. Schiesser〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A two-dimensional model for solute migration, transformation, and deposition in a phreatic solution conduit penetrating a karst aquifer is presented in which the solute is anthropogenic to the natural system. Transformation of a reacting solute in a solution conduit has generally been accepted as likely occurring but actual physical measurements and mathematical analyses of the suspected process have been generally minimally investigated, primarily because of the logistical difficulties and complexities associated with solute transport through solution conduits. The model demonstrates how a reacting solute might decay or be transformed to a product solute some of which then migrates via radial dispersion to the conduit wall where it may become adsorbed. Model effects vary for laminar flow and turbulent flow in the axial direction. Dispersion in the radial direction also exhibits marked differences for both laminar flow and turbulent flow. Reaction zones may enhance subsequent reactions due to some overlap resulting from the longitudinal dispersion caused by flow in the axial direction. Simulations showed that varying the reaction rate coefficient strongly affects solute reactions, but that varying deposition coefficients had only minimal impacts. The model was applied to a well-known tracer test that used the tracer dye, Rhodamine WT, which readily converts to deaminoalkylated Rhodamine WT after release, to illustrate how the model may be used to suggest one possible cause, in addition to other possible causes, for less than 100 tracer-mass recovery. In terms of pollutants in a karst aquifer the model also suggests one possible mechanism for pollutant transformation in a solution conduit.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169772218302134-ga1.jpg" width="411" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 217〈/p〉 〈p〉Author(s): Esa Puukko, Jukka Lehto, Antero Lindberg, Mikko Voutilainen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study aims to determine upscaling factors for the radionuclides' distribution coefficients (K〈sub〉d〈/sub〉) on crushed rocks to intact rock for the safety analysis of radionuclide migration from spent nuclear fuel in bedrock towards biosphere. Here we report the distribution coefficients for intact rock determined by electromigration sorption experiments and compare the results with those from recently performed batch sorption experiments. In total 34 rock samples, representing three typical rock types from Olkiluoto Finland, were studied in order to determine distribution coefficients, effective diffusion coefficients and porosities using the electromigration sorption experiments, formation factor experiments and porosity measurement. The parameters determined represent the three main parameters of geosphere used in the safety assessment of spent nuclear fuel disposal. The distribution coefficients of cesium and strontium on intact rock varied between (0.12–26.2) × 10〈sup〉−3〈/sup〉 m〈sup〉3〈/sup〉/kg and (1.4–13.3) × 10〈sup〉−3〈/sup〉 m〈sup〉3〈/sup〉/kg, respectively, whereas recent results for crushed rock varied between (2–57) × 10〈sup〉−3〈/sup〉 m〈sup〉3〈/sup〉/kg and (17–40) × 10〈sup〉−3〈/sup〉 m〈sup〉3〈/sup〉/kg, respectively. This implies that crushing increases the distribution coefficient significantly and upscaling factors from 3 to 33 were determined for scaling the distribution coefficients of crushed rock to ones of intact rock. The determined distribution coefficients of cesium and strontium for intact rock can be directly applied in the safety assessment whereas the upscaling factors can be used to convert distribution coefficients determined for crushed rock into ones for intact rock. Based on the results for porosities and effective diffusion coefficients it was concluded that they do not seem to correlate with sorption parameters. However, an alteration state, heterogeneity and mineral content seem to be important factors affecting the distribution coefficients and upscaling factors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 219〈/p〉 〈p〉Author(s): Saeid Shafieiyoun, Neil R. Thomson, Andrew P. Brey, Chris M. Gasinski, William Pence, Mike Marley〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Methods to remediate soil and groundwater contamination at former manufactured gas plant (FMGP) sites are scarce. The objective of this study was to investigate the ability of two chemical oxidants (persulfate and permanganate) to degrade FMGP residuals in a dynamic system representative of in situ conditions. A series of physical model trials supported by aqueous and slurry batch experiments using impacted sediments collected from a FMGP site were conducted. To explore treatment expectations a screening model constrained by the experimental data was employed. The results from the aqueous experiments showed that dissolved components (except for benzene) were readily degraded by persulfate or permanganate. In the well-mixed slurry systems, when contact with the oxidant was achieved, 95%, 45% and 30% of the initial mass quantified was degraded by permanganate, unactivated persulfate, and alkaline activated persulfate, respectively. In stark contrast, the total mass removed in the physical model trials was negligible for both permanganate and persulfate irrespective of the bleb or lense architecture used. Hence the net benefit of flushing 6 pore volumes of permanganate or persulfate at a concentration of 30 g/L under the physical model operating conditions was minimal. To achieve a substantial degradation of mass within the treatment system (〉40%), results from the screening model indicated that the hydraulic resident time would need to be 〉10 days and the average lumped mass transfer coefficient increased by two orders-of-magnitude. Results from long-term (5 years) simulations showed that the dissolved concentrations of organic compounds are reduced temporarily as a result of the presence of permanganate but then rebound to a profile that is essentially coincident with a no-treatment scenario following exposure to permanganate. Neither a lower velocity nor higher permanganate dosing affected the long-term behavior of the dissolved phase concentrations; however, increasing the mass transfer rate coefficient had an impact. The findings from this investigation indicate that the efficiency of permanganate or persulfate to treat for FMGP residuals is mass transfer limited.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Contaminant Hydrology, Volume 218〈/p〉 〈p〉Author(s): Li Meng, Rui Zuo, Jin-sheng Wang, Jie Yang, Yan-guo Teng, Rong-tao Shi, Yuan-zheng Zhai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Comparative analysis was performed of changing groundwater quality over ten years (2006–2016) by source apportionment and spatial distribution characteristics. This shallow groundwater in a typical riverside groundwater resource area was studied using principal component analysis (PCA) and factor analysis (FA), coupled with the absolute principal-component-score multiple-linear-regression (APCS-MLR) receptor model. The relationship among land-use types, hydro-chemical composition, and evolution of the quality of groundwater from natural and anthropogenic sources was demonstrated. The results showed that water-rock interaction, agricultural fertilizer, and domestic and industrial wastewater were responsible for the evolution of contamination in the groundwater. The major potential pollution sources that had significant effect on groundwater quality variables were categorized into three groups: heavy metals (iron, manganese), nutrients (ammonia nitrogen, nitrite and nitrates), and organic pollution (chemical oxygen demand). The APCS-MLR model considered the average contribution of each different potential pollution source to these categories separately. The potential pollution sources in the groundwater presented an obvious spatial distribution with an area of high concentration distributed mainly in the western and northwestern areas downstream from the Songhua River. The variation of land use type and evolution of the spatial distribution of the pollution sources in the groundwater showed good consistency. Eventually, PCA /FA coupled with APCS-MLR became a versatile tool for comprehensive source apportionment of groundwater.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169772218301104-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): Vittorio Gentile, Stefano Pierini, Paola de Ruggiero, Luca Pietranera〈/p〉 〈h5〉ABSTRACT〈/h5〉 〈div〉〈p〉In this paper the combined use of model simulations and altimeter data suggests that, during the interval 1998–2006, the Kuroshio Extension (KE) low-frequency variability was mainly of intrinsic origin. The model is based on the primitive equations for a reduced-gravity ocean, is eddy-permitting and relatively idealized, but it includes essential elements of realism and is driven by a time-independent climatological wind field, so that the modelled variability is necessarily of intrinsic oceanic origin. The altimeter data are provided by AVISO and include all the data available to date. A new composite index Λ[Φ] specifically conceived for the KE is used in the analysis of both model and altimeter data (Φ gives the mean latitudinal position of the KE jet and Λ is a measure of the high-frequency variability of the KE path). A set of sensitivity numerical experiments shows that the frontal dynamics is extremely sensitive to the horizontal eddy viscosity. A self-sustained relaxation oscillation emerging from a reference simulation is represented by a loop in the (Λ, Φ)-plane and is characterized by four phases, each one being controlled by a specific dynamical mechanism. An interval ranging from January 1998 to March 2006 is identified in the altimeter data, during which the altimeter-derived index is very similar to the modelled one. A detailed analysis based also on sea surface height maps shows that the real KE evolution possesses four phases characterized by basically the same dynamical behaviour recognized in the model loop. The conclusion is that, during that interval, the KE dynamics was controlled by an oceanic intrinsic mode of low-frequency variability and that the directly driven dynamics and ocean-atmosphere coupled modes of variability did not overshadow the intrinsic evolution. The self-sustained vs excited character of the relaxation oscillation is finally discussed.〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 132〈/p〉 〈p〉Author(s): Milan Klöwer, Malte F. Jansen, Martin Claus, Richard J. Greatbatch, Sören Thomsen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The parameterization of sub-grid scale processes is one of the key challenges towards improved numerical simulations of the atmospheric and oceanic circulation. Numerical weather prediction models as well as climate models would benefit from more sophisticated turbulence closures that allow for less spurious dissipation at the grid-scale and consequently higher and more realistic levels of eddy kinetic energy (EKE). Recent studies propose to use a hyperviscous closure in combination with an additional deterministic forcing term as a negative viscosity to represent backscatter of energy from unresolved scales. The sub-grid EKE is introduced as an additional prognostic variable that is fed by dissipation at the grid scale, and enables recycling of EKE via the backscatter term at larger scales. This parameterization was previously shown to work well in zonally re-entrant channel configurations. Here, a generalization in the form of a Rossby number-dependent scaling for the strength of the backscatter is introduced to represent the emergence of a forward energy-cascade in unbalanced flows near the boundaries. We apply the parameterization to a shallow water model of a double gyre basin and provide evidence for its general applicability. In terms of mean state and variability, a low resolution model is considerably improved towards a high resolution control run at low additional computational cost.〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): Samah El Mohtar, Ibrahim Hoteit, Omar Knio, Leila Issa, Issam Lakkis〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lagrangian tracking of passive tracers in a stochastic velocity field within a sequential ensemble data assimilation framework is challenging due to the exponential growth in the number of particles. This growth arises from describing the behavior of velocity over time as a set of possible combinations of the different realizations, before and after each assimilation cycle. This paper addresses the problem of efficiently advecting particles in stochastic flow fields, whose statistics are prescribed by an underlying ensemble, in a parallel computational framework (openMP). To this end, an efficient algorithm for forward and backward tracking of passive particles in stochastic flow-fields is presented. The algorithm, which employs higher order particle advection schemes, presents a mechanism for controlling the growth in the number of particles. The mechanism uses an adaptive binning procedure, while conserving the zeroth, first and second moments of probability (total probability, mean position, and variance). The adaptive binning process offers a tradeoff between speed and accuracy by limiting the number of particles to a desired maximum. To validate our method, we conducted various forward and backward particles tracking experiments within a realistic high-resolution ensemble assimilation setting of the Red Sea, focusing on the effect of the maximum number of particles, the time step, the variance of the ensemble, the travel time, the source location, and history of transport.〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 132〈/p〉 〈p〉Author(s): Anna Teruzzi, Giorgio Bolzon, Stefano Salon, Paolo Lazzari, Cosimo Solidoro, Gianpiero Cossarini〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The high spatial and temporal variability of biogeochemical features, induced by local dynamics and terrestrial and atmospheric inputs in shelf seas, are challenging issues for the implementation of data assimilation in these areas. The objective of this study is to integrate satellite ocean-colour observations with a coupled physical-biogeochemical model in order to improve the spatiotemporal descriptions of chlorophyll and other biogeochemical variables in the Mediterranean shelf seas. We adopted a specifically developed three-dimensional variational data assimilation scheme for the assimilation of satellite chlorophyll data. The non-homogeneous vertical component, the non-uniform and direction-dependent horizontal component of the background error covariance are the key features of the upgraded three-dimensional variational data assimilation scheme for shelf seas. The application of the new assimilation scheme significantly improves chlorophyll estimates in shelf seas, particularly in the representation of their spatial and temporal variability. Based on these results, we provide an estimate of the annual primary production of the Mediterranean basin.〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): César Sauvage, Cindy Lebeaupin Brossier, Véronique Ducrocq, Marie-Noëlle Bouin, Béatrice Vincendon, Marco Verdecchia, Isabelle Taupier-Letage, Françoise Orain〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Western Mediterranean Sea is often affected by heavy precipitation which frequently generates floods or even flash floods. These events generally produce brief but major freshwater inputs in the ocean. In order to evaluate the sensitivity to the representation of river freshwater input, three different runoff forcing dataset are used to drive the NEMO ocean model: a monthly climatology, an observational dataset with a daily or a hourly frequency. The sensitivity is investigated over the first Special Observation Period (SOP1) of the HyMeX program that took place in autumn 2012, in two configurations of NEMO: the first is WMED36 over the Western Mediterranean Sea at 1/36°-resolution and the second is a new configuration covering the North-Western Mediterranean Sea with a 1/72°-resolution named NWMED72. With NWMED72, the impact of the representation of the river freshwater flux, i.e. moving from a surface flux to a vertical distribution of the flux, is also evaluated. The results show that the ocean stratification is significantly modified locally in simulations where runoff observations are used compared to those using the climatology. The sea surface salinity is modified as well as the mixed layer which is thinner as bounded by a well marked halocline. The sea surface temperature is also impacted by the change in runoff frequency. Moreover, the current intensity in river plume during flood is increased. Vertical profiles of salinity and temperature and thus the mixed layer depth are changed when the runoff forcing is distributed over a depth. Those changes are limited and very local but the realism of the river runoff input is improved.〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 132〈/p〉 〈p〉Author(s): Rodrigo Mogollón, Paulo H.R. Calil〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We use a coupled physical–biogeochemical model to investigate the drivers and mechanisms responsible for the spatiotemporal variability of the partial pressure of carbon dioxide in seawater (〈em〉p〈/em〉CO〈sub〉2〈/sub〉) and associated air–sea CO〈sub〉2〈/sub〉 fluxes in the Northern Humboldt Current System (NHCS). Simulated 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 is in good agreement with available observations with an average absolute error of, approximately, 24 µatm. The highly productive upwelling region, 300 km from the shore and between 5 and 17 °S, is shown to be a strong CO〈sub〉2〈/sub〉 source with an averaged flux of 5.60   ±   2.94 mol C m〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mo〉−〈/mo〉〈mn〉2〈/mn〉〈/mrow〉〈/msup〉〈/math〉  year〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.gif" overflow="scroll"〉〈mrow〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mo〉−〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/msup〉〈mo〉,〈/mo〉〈/mrow〉〈/math〉 which represents an integrated carbon flux of 0.028   ±   0.015 Pg  C  year〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mo〉−〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/msup〉〈/math〉. Through a series of model experiments we show that the high 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 is primarily the result of coastal upwelling, which is incompletely compensated by biology. Specifically, the supply of dissolved inorganic carbon (DIC)-rich waters to the surface pushes 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 up to levels around 1100 µatm. Even though biological production is high, it reduces 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 only by about 300 µatm. We show that this relatively low degree of biological compensation, which implies an inefficient biological pump in the nearshore domain, results from a spatiotemporal decoupling between the counteracting effects of biological production and the transport and mixing of DIC. The contribution of the outgassing and the processes affecting CO〈sub〉2〈/sub〉 solubility, associated with the seasonal cycle of heating and cooling, are minor. Across the whole domain, the balance of mechanisms is similar, but with smaller amplitudes. We demonstrate that seawater 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 is more sensitive to changes in DIC and sea surface temperature, while alkalinity plays a minor role.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jinchang Li, Yuan Wang, Lisha Zhang, Liuyan Han, Guangyin Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Under a background of a significantly warming climate, current aeolian desertification in China's northeastern Tibetan Plateau (NETP) has been widely studied, but disagreements related to its causes continue to persist. In order to understand the present through the past, this study determined the various phases of aeolian desertification in the NETP based on the statistical analysis of 40 optically stimulated luminescence (OSL) aeolian sand dates from 23 aeolian sections. Because the redistribution of aeolian sand by wind processes can reduce the number of older sand dates, this research only affects exactly the past millennium. Following this, we analyzed the relationships between aeolian desertification phases in conjunction with reconstructed climatic data. Results revealed three distinct aeolian desertification phases that approximately correspond to 1480 CE, 1680 CE, and 1800 CE, respectively. By comparing these dates to well-established paleoclimate records, we determined that these three aeolian desertification phases all occurred under a cold and dry climate background. Accordingly, aeolian desertification in the NETP today under its current warm and wet climate background can therefore be attributable to irrational human activities rather than rising temperatures. Accordingly, we can infer that under the current warmer and wetter climate background, aeolian desertification in the NETP today can be reversed as long as human activities remain moderate, even without the implementation of artificial revegetation initiatives.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830417X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yitong Wang, Kai Yang, Zejun Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A field experiment was conducted to investigate the resistance to wind erosion of consolidated soil layer (CSL) on the edge of Ulan Buh Desert in Inner Mongolia, China under natural conditions during Aug. 2015–Apr. 2016. The CSLs consisted of sandy soil, fly ash (FA) (5%, 10% and 15% (w/w) soil) and polyacrylamide (PAM) (0.05% and 0.1% (w/w) soil). The experimental site was divided equally into Regions A and B where dry FA and PAM powder were applied in two ways in mid-Jul. 2015. In Region A, FA and PAM were mixed homogeneously with the 0–0.3 m depth topsoil. In Region B, FA alone was mixed homogeneously with the 0–0.3 m depth topsoil. PAM was then scattered uniformly on top of the surface layer. Finally, CSLs were formed by spraying an appropriate amount of water onto the surface to dissolve PAM fully and being equilibrated for one week to achieve a moisture content close to the initial soil moisture content (0.6%). It was found that during 2–26 Aug. 2015, the wind erosion rate (WER) was reduced most significantly by 77% in CSL (10%FA + 0.05%PAM) in Region A and by 58% in CSL (10%FA + 0.1%PAM) in Region B compared with control (CK) (WER = 10.2 kg/m〈sup〉2〈/sup〉). However, during 3–27 Sep. 2015, there was no significant difference in WER between treatments in Regions A and B compared with CK (WER = 1.4 kg/m〈sup〉2〈/sup〉). Whereas, during the following longer period of wind erosion (〈em〉viz.〈/em〉 27 Sep. 2015–21 Apr. 2016), the WER was reduced most significantly by 69% in CSL (5%FA + 0.1%PAM) in Region A and by 32% in CSL (5%FA + 0.05%PAM) in Region B compared with CK (WER = 80.7 kg/m〈sup〉2〈/sup〉). The resistance to wind erosion of CSL in Region A was much stronger than in Region B. The WER of CSL was influenced by wind conditions including wind speed and direction. Precipitation also had an impact on the WER of CSL as the cohesive effect of PAM can be influenced by precipitation. The CSL as a mixture of sandy soil, FA and PAM is recommended for wind erosion control.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830345X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Craig M. Hall, Heather N. Webb, Gary H. Girty, Amir A. Allam, Thomas K. Rockwell〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lying between the Elsinore and San Jacinto faults, ~0.5 km SE of Roundtop, is a tonalitic corestone perched precariously on an exhumed corestone base. Such features are referred to as precariously balanced rocks (PBRs). Cosmogenic 〈sup〉10〈/sup〉Be data listed in an online abstract suggest a tentative exhumation age of the PBR near Roundtop at ~35,000 years ago. The absence of PBRs adjacent to the Elsinore and San Jacinto faults implies that they were shaken free from their perches during ground shaking. Alternatively, their absence may reflect a more highly fractured and intensely weathered terrane. Because the weathering histories of PBRs have not been studied previously, we analyzed the texture, clay mineralogy, and geochemistry of the Roundtop PBR to answer several basic questions. Can the characteristics of the regolith that once encased the precariously balanced rock be reconstructed? What chemical processes operated in the regolith prior to exhumation, and are these processes still occurring? Following exhumation, did new fracture development modify the original regolith? To answer these questions, we extracted three ~1 m long cores from the PBR near Roundtop, and collected 23 saprock and 9 pebbly sandy loam samples from a trench excavated near the base of the corestone platform. Plagioclase and biotite alteration, along with the concomitant loss of Ca, Na, Sr, Ba, K, Mg, Mn, Nb, and P mass, are the primary evidence of weathering intensity within the saprock. Additionally, the presence of mostly kaolinite, and lesser quantities of mixed-layer biotite/smectite in the saprock, along with the above observations and data, point to significant fluid/rock interations during saprock development. Subsequent formation of pebbly sandy loam appears to have been accomplished primarily through pedoturbation within the uppermost portions of the underlying already weathered saprock, and produced little additional chemical weathering. Hence, our data support the general idea that Roundtop is an area of weak ground shaking, and that since current exhumation little weathering has affected this PBR locality.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): K. Hlavčová, M. Danáčová, S. Kohnová, J. Szolgay, P. Valent, R. Výleta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The paper focuses on the generation of floods as a principal soil threat and on soil erosion as an additional soil threat on arable lands of hillslope areas. As the most important component of floods causing the degradation of soils on arable lands, surface runoff is analysed in this study. The protective effect of crop management on the generation of surface runoff and sediment transport on arable lands is estimated on a plot and slope scale. The site of the case study, which is located in the Myjava river basin in western Slovakia, is a hilly agricultural field with an area of 29 ha; it is characterised by arable soil, extreme erosion processes, and muddy floods. Field rainfall simulation experiments were combined with physically-based modelling for studying the formation of surface runoff under various soil covers. The field experiments consisted of simulating runoff generation from artificial rainfalls using the Eijkelkamp rainfall simulator on experimental plots with a focus on estimating the volume of surface runoff, the mass of sediments transported by the surface runoff, and the time to runoff. The volumes of the surface runoff and the values of the time to runoff have been applied in the parameterisation of the SMODERP physically-based hydrological model. The hydrological modelling of the surface runoff on the selected slope profile quantified the protective effect of various soil covers on reducing surface runoff. The outcome of the modelling was the maximum allowed lengths of the slope that represent the crucial values for flood and erosion control. When exceeding these critical values, protective measures, e.g., vegetation strips, should be proposed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Chang-An Liu, Yu Nie, Xin Rao, Jian-Wei Tang, Kadambot H.M. Siddique〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rubber-based (〈em〉Hevea brasiliensis〈/em〉) agroforestry systems are the best way to resolve the environmental problems caused by rubber monoculture. Rubber–〈em〉Flemingia macrophylla〈/em〉 (nitrogen-fixing plants) systems have become popular in Xishuangbanna, Southwest China. Soil water content and exchangeable cations (Ca〈sup〉2+〈/sup〉, Mg〈sup〉2+〈/sup〉, K〈sup〉+〈/sup〉, and Na〈sup〉+〈/sup〉) are important for sustainably managing forest ecosystems. In this study, we investigated the responses of soil water content and exchangeable cations in rubber and rubber–〈em〉Flemingia macrophylla〈/em〉 systems. Soil water content increased in the 0–90 cm soil layer as the rubber plantations aged, and the mature rubber plantations had similar soil water storage to rainforests. The rubber plantations use soil water in the 30–90 cm soil layer to avoid drought stress during the long, dry season. The introduction of 〈em〉Flemingia macrophylla〈/em〉 to the young rubber plantations significantly increased soil water depletion in the 30–90 cm soil layer. The introduction of 〈em〉Flemingia macrophylla〈/em〉 to the mature rubber plantations had no significant effects on soil water in the 0–90 cm soil layer. The introduction of 〈em〉Flemingia macrophylla〈/em〉 to the differently aged rubber plantations mitigated soil acidification by decreasing nitrogen inputs. The total exchangeable cations in the 0–90 cm soil layer sharply decreased as the rubber plantations aged due to the acceleration of soil acidification. When soil pH was below 5.5, 7.85 cmol kg〈sup〉−1〈/sup〉 of soil exchangeable cations were released when the pH decreased by one unit. However, the introduction of 〈em〉Flemingia macrophylla〈/em〉 to the differently aged rubber plantations effectively reduced the release of soil exchangeable cations by mitigating soil acidification. In conclusion, rubber–〈em〉Flemingia macrophylla〈/em〉 systems can mitigate soil acidification and reduce the release of soil exchangeable cations relative to rubber monoculture.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S034181621830362X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Diego Luciano do Nascimento, Alessandro Batezelli, Francisco Sérgio Bernardes Ladeira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rhizoliths are organosedimentary structures produced by plants and are an important proxy for paleoenvironmental reconstructions because the differences in the morphology of rhizoliths and their rooting depths can be used to interpret soil humidity regimes, overall biomass at the soil surface, and the behavior of the water table. With the objective of advancing knowledge on rhizoliths, a study was performed on the macromorphological and micromorphological characterizations of the rhizoliths preserved in the thirty-one paleosols of the Marília Formation in Minas Gerais, southeastern Brazil. Based on the topological and architectural attributes of rhizoliths, and on their possible functional adaptations, such as mycorrhizal associations, three different types of rhizoliths are described in this study and represent at least three different plants: rhizohaloes, root casts and rhizocretions. Well-developed paleosols with nodular horizons contain the higher density of long root casts, indicating a seasonally dry environment, because the root casts present two meters in length. These adaptations are associated with an exploitation of a lowered water table during most times of the year. The higher density of rhizoliths indicates an area with agglomerated arboreous arbustive vegetation cover. Paleosols with chalky horizons also show a high density of root casts, indicating a landscape with high plant density that is adapted to drained soils, but with a seasonally elevated water table or the influence of ephemeral flows, given the proximity to the flow channels. The poorly drained paleosols with redoximorphic features show the lowest density of rhizoliths, thus indicating an incipient vegetation in response to near-surface water table and waterlogged soils in a distal floodplain. The rhizogenic laminar horizons have developed near fluvial channels with frequent sedimentary input, resulting in a sequence of laminar horizons composed of rhizocretions that are separated by sandy deposits or poorly developed pedogenic horizons. The micromorphological analysis on the rhizogenic laminar calcretes showed biogenic features, such as alveolar septal structures, calcified filaments, microcodium, calcified cells and pisoliths. Despite the scarce paleobotanical findings in the Marília Formation, the results obtained indicate an ecosystem that was composed of plants varying from herbaceous to arboreous, with an environment similar to modern semiarid shrublands.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218304181-ga1.jpg" width="407" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yiwei Lyu, Shan Zheng, Guangming Tan, Caiwen Shu, Qi Han〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To investigate the evolution characteristics of the Yichang–Chenglingji Reach (YCR) of the Middle Yangtze River and develop simulation methods, the temporal and spatial morphodynamic adjustments of the YCR were analysed comprehensively on the basis of runoff, sediment load, and cross-sectional profiles data at 220 cross sections from 2002 to 2016. Results showed that significant channel degradation has occurred in the YCR, especially in the low-flow channels, due to a drastic reduction in sediment yield since the operation of the Three Gorges Project (TGP). The variations of upstream flow and sediment regimes would drive equilibrium channels to become increasingly narrow and deep, and the current bankfull width and depth were less than their equilibrium counterparts in the recent period. However, the recent channel evolution was mainly characterized by the prominent channel deepening via a one-way deformation due to the large-scale bank revetments within the YCR, where the reach-scale bankfull depth increased by 1.6 m in the span of 15 years. A semi-empirical method for determining the equilibrium values of channel degradation and aggradation volume at the YCR was proposed on the basis of a comprehensive analysis of the effects of flow, sediment concentration, sediment gradation, and water depth. Moreover, the equilibrium values of the channel width and depth were estimated with the Least Action Principle method. The calculation methods for the equilibrium width, depth, width/depth ratio, and aggradation/degradation volume were combined with the Delayed Response Model (DRM). Then, the methods for calculating the variations in channel geometry and aggradation/degradation volume were derived. Results showed that the proposed methods effectively simulated the channel geometry and cumulative erosion volume in the YCR from 2002 to 2016. In addition, the response of the channel evolution in the YCR was closely related to the previous four-year hydrological conditions, implying that channel evolution may lag behind the variations of flow and sediment discharges.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Andre Acksel, Luise Giani, Carolin Stasch, Peter Kühn, Sebastian Eiter, Kerstin Potthoff, Tom Regier, Peter Leinweber〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Some previous studies showed that the formation of several deep dark humus-rich topsoils in Northern Europe was strongly influenced by the application of different organic materials by anthropogenic activities in former times. Such topsoils classified as plaggic Anthrosols also occurred in the Jæren region in SW Norway. However, source material and formation time of these Plaggic Anthrosols have not yet been clarified. Close to this region we found further humus-rich topsoils in the Karmøy municipality (2 sites at main island of Karmøy and 1 site at Feøy). These soils show a thick humus-rich topsoil up to 30 cm, and their formation cannot only be explained by natural conditions. We analyzed the molecular signature of the soil organic matter (SOM) by benzene polycarboxylic acids (BPCA), non-targeted bulk SOM mass spectrometry, δ〈sup〉34〈/sup〉S and 〈sup〉14〈/sup〉C AMS dating in order to determine source materials and the age of the SOM. The black carbon (BC) contents of the plaggic soils in Jæren (mean 3.4 g kg〈sup〉−1〈/sup〉) deliver clear evidence for inputs of combustion residues from ancient fire management and/or from settlements. The C-XANES and Py-FIMS-spectra reveal relative enrichments of aromatic C and heterocyclic N compounds in the plaggic soils corresponding to the BC contents. In contrast, the humus-rich topsoils in Karmøy seem to be unaffected by fire management due to the low BC contents (mean 0.6 g kg〈sup〉−1〈/sup〉) and the relative low portions of aromatic C and heterocyclic N compounds from C-XANES and Py-FIMS. The δ〈sup〉34〈/sup〉S isotope signature of the SOM ranged from 10.6 to 15.2‰ in the soils at the islands and 10.0 to 13.5‰ in Jæren, corresponding to the Anthrosols in the Baltic Sea region (Median: δ〈sup〉34〈/sup〉S = 11.5‰) and suggest an input of marine biomass (δ〈sup〉34〈/sup〉S of seaweed = 20‰). The AMS 〈sup〉14〈/sup〉C dating and complementary archaeological literature implied that the soils in Jæren and Karmøy have been formed between the Roman Iron Age (500 BC to AD 500) and the Viking Age (AD 800 to AD 1,000). Our results provide strong evidence for an anthropo-pedogenesis of the humus-rich topsoils in Karmøy and indicate parallels to the plaggic soils in Jæren as well as to Anthrosols in the Baltic Sea region. Therefore, we propose to classify the humus-rich topsoils in Karmøy as Anthrosols.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Israel Carmi, Joel Kronfeld, Murray Moinester〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Inorganic carbon, as allogenic and pedogenic carbonates mixtures, can be a significant component of arid and semi-arid zone soils. It has been claimed, that the formation of pedogenic carbonates does not sequester atmospheric carbon dioxide, when formed from the preexisting limestone: Ca〈sup〉+2〈/sup〉 + 2HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 → CaCO〈sub〉3〈/sub〉 ↓ + CO〈sub〉2〈/sub〉 ↑ + H〈sub〉2〈/sub〉O. But if the cation is derived from a non‑carbonate source sequestration can occur. Among the unconsidered sources in nature are the contribution of Ca〈sup〉+2〈/sup〉, released from adsorption sites on the clay surfaces. Analysis of DIC, δ〈sup〉13〈/sup〉C and Δ〈sup〉14〈/sup〉C data show in the present study that sequestration does occur within the unsaturated zones (USZ) in a semiarid region: 1) the DIC is depleted as carbonate precipitates into the USZ, 2) the released CO〈sub〉2〈/sub〉, does not immediately return to the atmosphere (except for the samples nearest to the surface) but recycles to the soil-gas of high CO〈sub〉2〈/sub〉 partial pressure, and 3) that radiocarbon, which is generated only in the overlying atmosphere, and exhaled into the USZ by roots and the decay of soil organic matter, is incorporated within the calcite mineral. Thus, a net sequestration of atmospheric CO〈sub〉2〈/sub〉 does occur.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 25 April 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA〈/p〉 〈p〉Author(s): C.J. Williams, Frederick B. Pierson, Sayjro K. Nouwakpo, Osama Z. Al-Hamdan, Patrick R. Kormos, Mark A. Weltz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pinyon (〈em〉Pinus〈/em〉 spp.) and juniper (〈em〉Juniperus〈/em〉 spp.) woodland encroachment has imperiled a broad ecological domain of the sagebrush steppe (〈em〉Artemisia〈/em〉 spp.) ecosystem in the Great Basin Region, USA. As these conifers increase in dominance on sagebrush rangelands, understory vegetation declines and ecohydrologic function can shift from biotic (vegetation) controlled retention of soil resources to abiotic (runoff) driven loss of soil resources and long-term site degradation. Scientists, public land management agencies, and private land owners are challenged with selecting and predicting outcomes to treatment alternatives to improve ecological structure and function on these rangelands. This study is the first of a two-part study to evaluate effectiveness of prescribed fire to re-establish sagebrush steppe vegetation and improve ecohydrologic function on mid- to late-succession pinyon-and juniper-encroached sagebrush sites in the Great Basin. We used a suite of vegetation and soil measures, small-plot (0.5 m〈sup〉2〈/sup〉) rainfall simulations, and overland flow experiments (9 m〈sup〉2〈/sup〉) to quantify the effects of tree removal by prescribed fire on vegetation, soils, and rainsplash, sheetflow, and concentrated flow hydrologic and erosion processes at two woodlands 9-yr after burning. For untreated conditions, extensive bare interspace (87% bare ground) throughout the degraded intercanopy (69–88% bare ground) between trees at both sites promoted high runoff and sediment yield from combined rainsplash and sheetflow (~45 mm, 59–381 g m〈sup〉−2〈/sup〉) and concentrated flow (371–501 L, 2343–3015 g) processes during high intensity rainfall simulation (102 mm h〈sup〉−1〈/sup〉, 45 min) and overland flow experiments (15, 30, and 45 L min〈sup〉−1〈/sup〉, 8 min each). Burning increased canopy cover of native perennial herbaceous vegetation by 〉5-fold, on average, across both sites over nine growing seasons. Burning reduced low pre-fire sagebrush canopy cover (〈1% to 14% average) at both sites and sagebrush recovery is expected to take 〉30 yr. Enhanced herbaceous cover in interspaces post-fire reduced runoff and sediment yield from high intensity rainfall simulations by 〉2-fold at both sites. Fire-induced increases in herbaceous canopy cover (from 34% to 62%) and litter ground cover (from 15% to 36%) reduced total runoff (from 501 L to 180 L) and sediment yield (from 2343 g to 115 g) from concentrated flow experiments in the intercanopy at one site. Sparser herbaceous vegetation (49% cover) and litter cover (8%) in the intercanopy at the other, more degraded site post-fire resulted in no significant reduction of total runoff (371 L to 266 L) and sediment yield (3015 g to 1982 g) for concentrated flow experiments. Areas underneath unburned shrub and tree canopies were well covered by vegetation and ground cover and generated limited runoff and sediment. Fire impacts on vegetation, ground cover, and runoff and sediment delivery from tree and shrub plots were highly variable. Burning litter covered areas underneath trees reduced perennial herbaceous vegetation and increased invasibility to the fire-prone annual cheatgrass (〈em〉Bromus tectorum〈/em〉 L.). Cheatgrass cover increased from 〈1% pre-fire to 16–30%, on average, post-fire across the sites and was primarily restricted to areas around burned trees. High herbaceous cover (73%) under burned trees at the less degraded site resulted in similar low total runoff and sediment from concentrated flow experiments as pre-fire (136–228 L, 204–423 g). In contrast, fire-reduction of litter (from 79% to 49%) resulted in increased total runoff (from 103 L to 333 L) and sediment yield (from 619 g to 2170 g) from concentrated flow experiments in burned tree areas at the more degraded site. The experimental results demonstrate pinyon and juniper removal by prescribed fire can effectively re-establish a successional trajectory towards sagebrush steppe vegetation structure and thereby improve ecohydrologic function. Responses to burning at the more degraded site suggest results should be interpreted with caution however. Although burning substantially increased perennial grass cover and reduced fine-scale runoff and erosion at the more degraded site, poor sagebrush recovery, delayed litter recruitment, and persistent high concentrated flow erosion at that site suggest not all sites are good candidates for prescribed fire treatments. Furthermore, high levels of cheatgrass in burned tree areas (~30% of area) at both sites increases wildfire risk, but cheatgrass is expected to decline over time in absence of fire. Our results in context with the literature suggest fire-surrogate tree-removal treatments (e.g., tree cutting or shredding) may be more appropriate on degraded sites with limited pre-treatment sagebrush and perennial herbaceous vegetation and that seeding may be necessary to improve post-fire establishment of sagebrush steppe vegetation structure and associated ecohydrologic function under these conditions. Lastly, vegetation, runoff, and erosion responses in this study are not directly applicable outside of the Great Basin, but similar responses in woodland studies from the southwestern US suggest potential application of results to woodlands in that region. The concept of re-establishing vegetation structure to improve ecohydrologic function is broadly applicable to sparsely vegetated lands around the World.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Xuemei Mei, Lan Ma, Qingke Zhu, Bai Li, Dong Zhang, Huifang Liu, Qianing Zhang, Qingping Gou, Mingshuang Shen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil water storage (SWS) is a critical water resource for vegetation growth in the Loess Plateau. Changes in SWS during the growing season can reflect soil water depletion or recharge conditions in different hydrological years. This study investigated the soil water in three hillslopes covered with artificial forest, natural forest and natural grass in May and October of 2015–2017. Both path analysis and stepwise multiple linear regression were used to determine the direct and indirect effects of most important variables and develop a model for predicting changes in SWS. The results showed that compared with natural forestland and grassland, artificial forestland had low soil water, but deep SWS maintained a balance of inputs and outputs. In all soil layers, during the growing season, total precipitation (X〈sub〉4〈/sub〉) was the most important variable affecting changes in SWS. The changes in SWS in surface soil layers were affected by more environmental factors than in deeper soil layers. The natural grassland (X〈sub〉3〈/sub〉) and slope position (X〈sub〉12〈/sub〉) have different degree of direct and indirect effects by means of antecedent soil water content (X〈sub〉5)〈/sub〉, even though their correlations were not significant. In addition, changes in SWS at the 0–100 cm, 100–200 cm and 0–400 cm soil layers were adequately predicted using the multiple regression equation, in which R〈sup〉2〈/sup〉 reached values from 73.4–93.0%. The model simulating the changes in SWS during the growing season can improve understanding on whether rainfall infiltration can replenish soil water depletion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Fengyan Zhao, Yongyong Zhang, Feike A. Dijkstra, Zhijun Li, Yueqi Zhang, Tianshi Zhang, Yingqi Lu, Jinwei Shi, Lijuan Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phosphate fertilizers are used in horticultural production to increase yields, but overuse can result in inefficient crop uptake and large loss of phosphorus (P). Soil amendments could potentially reduce the risk of P loss while maintaining high crop yield. The objective of this study was to investigate the effect of organic and inorganic amendments on P fractions in soils with different P levels (low, medium and high), and the underlying mechanisms. Five treatments were included: no amendment (CK), chemical fertilizers (CF), rice straw (FS), chicken manure compost (CM), and vermicompost (VM). Counterintuitively, the proportion of organic phosphorus (OP) tended to increase in the CF treatment, especially in soil with low P level. Results indicated that the change in the proportion of OP was mainly controlled by soil acid phosphomonoesterase, alkaline phosphomonoesterase and phosphate-solubilizing microorganisms. The proportion of available P increased in soil with low P level, but decreased in soil with high P level in the VM treatment. Non-labile P was preferentially formed in the VM treatment because of the high calcium content in vermicompost. Phosphates associated with aluminum (Al-P) were significantly higher in the CM treatment than in other treatments. This treatment also had a large presence of 〈em〉Pseudomonas〈/em〉 and 〈em〉Streptomyces〈/em〉 bacteria, which are capable of promoting the formation of Al-P. Our results indicated that mechanisms causing changes in soil P fractions were distinctly different among various amendments, and that vermicompost had the greatest potential to increase P supply in soil with low P level, and to decrease the risk of P loss in soil with high P level.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303424-ga1.jpg" width="422" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Yoshinori Shinohara, Yuma Misumi, Tetsuya Kubota, Kazuki Nanko〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In Japan, moso-bamboo (〈em〉Phyllostachys edulis〈/em〉 (Carrière) J. Houz.), an invasive species, has spread into and replaced surrounding broadleaved and coniferous forests because of the inactive management of moso-bamboo forests. Some local governments in Japan have speculated about an increase in soil erosion caused by the replacement with moso-bamboo forests. To evaluate the impact of such replacement on soil erosion, the soil erosion rate in a moso-bamboo forest was compared with those in an evergreen broadleaved forest and a coniferous forest. We established three plots (width 1 m, length ca. 2 m) in each forest and measured overland flow and soil erosion in two continuous periods (Period I: July 26, 2012–April 26, 2013; Period II: April 26, 2013–July 17, 2014). In Period I, the soil erosion rate in the moso-bamboo forest (0.08–0.10 g m〈sup〉−2〈/sup〉 mm〈sup〉−1〈/sup〉) was not significantly higher than that in the broadleaved forest (0.27–0.55 g m〈sup〉−2〈/sup〉 mm〈sup〉−1〈/sup〉) and the coniferous forest (0.16–0.27 g m〈sup〉−2〈/sup〉 mm〈sup〉−1〈/sup〉). In Period II, we removed understory vegetation and litter from two of the three plots in each forest. In Period II, the plots with such removal had higher soil erosion rates than the control plots. The soil erosion rate for the removal plots of the moso-bamboo forest was less than half of those of the broadleaved and coniferous forests. Although rock fragment cover on the soil surface and shear strength of the topsoil did not differ significantly among the three forests, root density in the moso-bamboo forest was much greater than those in the broadleaved and coniferous forests. These results suggest that a large amount of roots in moso-bamboo forests could reduce soil erosion there. The findings of this study show that moso-bamboo forests have strong resistance against soil erosion, so the replacement of broadleaved and coniferous forests by moso-bamboo forests would not seem to imply an increase in soil erosion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 173〈/p〉 〈p〉Author(s): Namratha Reddy, David M. Crohn〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Amending saline-sodic soils with organic manures and composts can help to remediate them by improving their physical, chemical, and biological properties. Little is known as to how temperature effects organically amended saline-sodic soils in terms of soil nitrogen (N) dynamics, greenhouse gases, and dinitrogen (N〈sub〉2〈/sub〉) emissions, however. The effects of soil temperature and organic matter applications to a saline-sodic soil on CO〈sub〉2〈/sub〉, N〈sub〉2〈/sub〉O, and N〈sub〉2〈/sub〉 emissions were investigated. An extreme saline-sodic soil with electrical conductivity (EC〈sub〉e〈/sub〉) 100 dS m〈sup〉−1〈/sup〉 and pH 7.8 was used in this study. Four organic amendment treatments were selected: active greenwaste (AGW), cured greenwaste compost (CGW), active dairy manure (ADM), and cured dairy manure compost (CDM). All treatments were incorporated at 100 Mg ha〈sup〉−1〈/sup〉 and incubated at 70% water-filled pore space (WFPS) for 60 days at 15, 25, and 35 °C. Relative to 15 °C emissions, increasing soil temperatures significantly enhanced cumulative CO〈sub〉2〈/sub〉, N〈sub〉2〈/sub〉O, and N〈sub〉2〈/sub〉 losses from all treatments. The emissions of CO〈sub〉2〈/sub〉 increased in the AGW and ADM by 1.5 to 2.2 fold compared to CGW and CDM amended soils at all three temperatures. Higher cumulative N〈sub〉2〈/sub〉O-N emissions were released from ADM compared to AGW and CDM compared to CGW treatments at 25 and 35 °C, respectively. At 25 and 35 °C, AGW and CDM increased N〈sub〉2〈/sub〉 emissions relative to ADM and CGW, respectively. It was found that soil temperature had a significant effect on CO〈sub〉2〈/sub〉, N〈sub〉2〈/sub〉O, and N〈sub〉2〈/sub〉 emissions. However, CO〈sub〉2〈/sub〉 production highly correlated with N〈sub〉2〈/sub〉 emissions indicating that active organic materials could be carefully applied to remediate saline-sodic soils while mitigating N〈sub〉2〈/sub〉O emissions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Mohamad Basel Al Sawaf, Kiyosi Kawanisi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To assess the dynamics of rivers, a reliable characterization of river streamflow during unsteady flow regimes is of paramount importance. In this work, we aimed at investigating the characteristics of turbidity–discharge (T–Q) dynamics corresponding to annual artificial dam flush release in a mountainous stream. Two methods for evaluating discharge were used in this study: the classical rating curve and the fluvial acoustic tomography (FAT) system that was developed by Hiroshima University. Interestingly, during dam flush, the discharge records obtained by FAT showed striking features of unsteady streamflow behavior, such as discharge shoulders and, in some events, secondary discharge peaks. According to the T–Q hysteresis loops, the common type of T–Q observed patterns were anticlockwise loops. During the studied DF events, sediment was supplied by river banks located at different sites along the river channel.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Jie Du, Jianzhi Niu, Zhaoliang Gao, Xiongwen Chen, Linus Zhang, Xiang Li, Natalie S. van Doorn, Ziteng Luo, Zhijun Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rainfall interception and other hydrologic processes affected by the forest litter layer are usually related to litter characteristics and rainfall conditions, with limited studies that consider the influence of slope. To simulate the hydrological functions of the litter layer at different slope gradients, artificial rainfall experiments were conducted at four rainfall intensities (from 30 to 120 mm hr〈sup〉−1〈/sup〉) in horizontal and inclined trays (with the slope of 0°, 10°, 20° and 30°) with litter of 〈em〉Pinus tabuliformis〈/em〉 or 〈em〉Quercus variabilis〈/em〉. The results indicated that (1) the dynamic process of litter interception had 3 phases: a rapid intercepted phase within the first 5 min, a moderate intercepted phase and a post-rainfall drainage phase; (2) the maximum interception storage (〈em〉C〈/em〉〈sub〉max〈/sub〉) and the minimum interception storage (〈em〉C〈/em〉〈sub〉min〈/sub〉) of 〈em〉Q. variabilis〈/em〉 were larger than those of 〈em〉P. tabuliformis〈/em〉; (3) 〈em〉C〈/em〉〈sub〉max〈/sub〉 and 〈em〉C〈/em〉〈sub〉min〈/sub〉 were correlated with slope for both types of litter, whereas only 〈em〉C〈/em〉〈sub〉max〈/sub〉 was correlated with rainfall intensity; and (4) lateral flow amount significantly increased with both slope gradient and rainfall intensity only for 〈em〉Quercus variabilis〈/em〉, whereas drainage volume showed significant correlation with rainfall intensity. Moreover, the ratio of lateral runoff and drainage was affected by slope gradient whereas percentage of litter interception had a good relationship with rainfall intensity, rather than slope, with litter interception and drainage contributing the smallest and the largest proportions, respectively. Overall, the results demonstrate the effect of rainfall and slope factors on hydrological processes in the forest litter layer.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Sri Rahayu Utami, Florias Mees, Mathijs Dumon, Nikolla P. Qafoku, Eric Van Ranst〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We studied the relationship between the mineralogical composition and surface charge properties of representative Quaternary volcanic ash soils, classified as Andosols, along an East-West sequence on Java Island in Indonesia. The soil charge characteristics were determined using ‘charge fingerprinting’ procedures. Most of the studied soils have a limited ability to retain cations under their forest or grass vegetation. The surface charge properties of these soils are mainly related to allophane and organic matter contents and, to a lesser degree, to ferrihydrite content and layer silicate characteristics. In East Java, the soils are Andosols with low allophane content, dominated either by halloysitic clays or by a mixture of 2:1 and 1:1 layer silicate clays; these soils are characterized by a low to moderate permanent charge. In West Java, the soils are rich in allophane, with subordinate kaolinitic clays, gibbsitic material or a mixture of 1:1 and 2:1 layer silicate clays; in contrast to the allophane-poor soils of East Java, these soils have extreme variable charge characteristics, creating a net ‘positive’ variable surface charge at soil pH. Differences in mineralogical composition of the clay fraction are attributed mainly to more pronounced seasonality in East Java, with variations in parent ash composition, becoming more acidic from east to west, as subordinate factor. The more severely leaching environment in West Java results in a higher degree of desilication, which led to a higher point of zero net charge (PZNC) and pHo in the allophane-rich soils. This study demonstrates how a climatic gradient can affect regional variations in charge properties, through the impact of climate on the mineralogical composition of the clay fraction. Regional patterns of this type must be understood to correctly assess of variations in soil fertility status and to make correct soil management choices for sustainable crop production.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0341816218303928-ga1.jpg" width="467" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management〈/p〉 〈p〉Author(s): Marco Mereu, Alessandro Cau, Blondine Agus, Rita Cannas, Maria Cristina Follesa, Paola Pesci, Danila Cuccu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The aim of the present study was to evaluate, through a Collaborative Fisheries Research (CFR) project, the efficacy of artificial dens as a possible integrative action for the management of 〈em〉O. vulgaris〈/em〉 in the wild. Artificial dens, anchored on rocky substrates at a depth of 38–42 m in a temporary Fully Protected Area (FPA) off the western coast of Sardinia (central western Mediterranean Sea), showed their effectiveness as a temporary and/or safe site for 〈em〉Octopus vulgaris〈/em〉 spawning. The suitability of these artificial dens was demonstrated by the presence of egg strings and females in parental care, and by the fact that all of the brooding-phases until the hatching had taken place inside. The presence of abundant cobbles, appeared to be a key factor in the building of a solid barrier for protection at the entrance of the spawning artificial dens, similar to those seen in natural dens. In addition, our results demonstrate the potential coexistence of artificial dens with natural ones, suggesting their potential use as integrative tool for the management of 〈em〉O. vulgaris〈/em〉. Close collaboration with fishermen in the framework of a CFR project within FPA may increase the success of this management action, through the enforcement of the area. Brooding details and laid egg features revealed by the monitoring are reported and discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 165〈/p〉 〈p〉Author(s): Ruth Beatriz Mezzalira Pincinato, Frank Asche〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Seafood imports have increased strongly in emerging economies during the last decades. However, the impacts of increased imports on price determination process, local fishers' income and fish stocks have received limited attention. This paper presents a market integration and price transmission analysis for the Brazilian sardine market, comprising the fresh and canned sardines segments, to shed light on these issues. Imports currently supply about one-half the sardines in the Brazilian market, and even more when the domestic fishery landings are low. The results suggest not only a fully integrated market but also a complete price transmission in both sardine value chains. Hence, import competition with domestic fisheries limit price increases in the domestic fishery and reduce fishers' income and fishing effort. However, the canneries, consumers and fish stocks are better off.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 15 April 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management〈/p〉 〈p〉Author(s): Xun Li, Jinliang Huang, Zhenshun Tu, Shunliang Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent shoreline management efforts have extended the scope of management plan to address multi-stakeholders’ conflicts over the use of coastal resources and their preservation. As cell identification is a critical step towards the development of Shoreline Management Plan (SMP), this paper provides the needed evidence to justify its rationality using Longhai city as a testing site. The coastal zone boundary of Longhai city was firstly defined taking into consideration the interface between land and sea. Seven cell units were identified with due consideration of existing plans. Subsequently, Multi-criteria Decision Making analysis coupled with GIS techniques was performed to verify the rationality of the cell identification. The results justified and supported the cell identification approach and outcomes with respect to dominant sectors within each unit, as well as the integrative and adaptive characteristics of the SMP in balancing environmental conservation and socioeconomic development. The quantitative approach further enables evaluating its adaptability in a changing environment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 4 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management〈/p〉 〈p〉Author(s): Wanfei Qiu, Xuan Zhu, Miaozhuang Zheng, Yan Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper addresses key drivers and enabling conditions for implementing Integrated Coastal Management (ICM) programs in Xiamen, China. The drivers for initiating and implementing ICM programs in Xiamen included a growing level of environmental awareness, multiple-use conflicts and the need for more integrated coastal and ocean governance, and a clear vision and leadership from the Xiamen Municipal Government. Similar to other successful ICM initiatives, the efforts in Xiamen demonstrated the importance of action plans, a legislative framework, financial sustainability, information management and dissemination, and capacity development in providing for an enabling environment for ICM activities. Strong political will and leadership from the Municipal Government, underpinned by local autonomy over coastal resource management, are also highlighted as key factors that provided for successful outcomes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 166〈/p〉 〈p〉Author(s): M.V. Krylenko, V.V. Krylenko, T.A. Volkova〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Dolgaya spit is the large accumulative bodies on the Russian coast of the Sea of Azov. Plots of natural forest-steppe and wetland landscapes with unique flora and fauna were preserved there. A part of the Dolgaya spit is a natural landmark of regional significance. Sand and shell beaches of the Dolgaya spit are actively used for recreational purposes being the basis of social and economic development of the Dolzhanskaya resort. The presence of anthropogenic and natural threats impedes sustainable development of the Dolgaya spit geographical complex. Our study is aimed at search of a solution to this issue.〈/p〉 〈p〉Field studies that include the analysis of natural features and anthropogenic changes were carried out in the course of the work. In addition, the conducted studies were based on the analysis of the remote sensing data. An important part of the research were opinion polls and the analysis of urban planning and statistical information.〈/p〉 〈p〉As the results of the social researches show, the most attractive natural factors in the choice of the Dolzhanskaya resort as the place of vacation are the sea, the beaches, clean dry air, steppe vegetation and spaciousness. Negative factors are predominantly social and economic ones: low level of recreational infrastructure and service, poor transport accessibility.〈/p〉 〈p〉The lack of a balanced strategy impedes the development of the Dolzhanskaya resort. Uncontrolled development resulted in excessive traffic and recreational load, spontaneous development, lack of transport and recreational infrastructure and destruction of natural landscapes. The situation is aggravated by serious natural threats. The distal part of the northeast coast of the spit erodes and draws back.〈/p〉 〈p〉On the basis of the received information, it was possible to develop recommendations on economic use and conservation of the Dolgaya spit. The landscape approach in the scientifically grounded organization of the functional and morphological structure of the resort and reservation within the Dolgaya spit will help to maintain and develop its economic and environmental potential.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 7 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management〈/p〉 〈p〉Author(s): Meina Su, Benrong Peng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study presents three case studies of integrating coastal ecosystem services' value into decision making in Xiamen under the integrated coastal management (ICM) framework. Xiamen's experiences show that integrating the values of ecosystem services into decision making can harmonize coastal economic development, environmental protection, and local stakeholders' concerns regarding preserving the ecosystems they depend on. Scientists play a critical role in integrating the values of ecosystem services into decision making by convincing policymakers and concerned stakeholders that the benefits and costs of development and conservation of ecosystems are worthwhile. ICM also provides the required operational framework and policy mechanism for incorporating ecosystem services and their values into decision making, especially at times of market and institutional failures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 166〈/p〉 〈p〉Author(s): Nikolaos Rempis, George Alexandrakis, Georgios Tsilimigkas, Nikolaos Kampanis〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coastal zones are submitted to pressures, due to population growth and continuous expansion of human activities, which become more intense by the effects of climate change. These pressures lead coastal administrators and stakeholders into taking actions to protect and further develop the coastal zones. Those actions are not always within the framework of spatial plans. Land-Sea interaction is an important factor that should be taken into account during the implementation of Spatial Plans. To this end, assuring the coherence between coastal terrestrial and marine planning is a prerequisite, as the coastal zone is the link between marine and terrestrial space. This paper aims to identify the land and sea uses interactions that result from a series of projects. As case study, the wider area of Heraklion, Crete Island, is considered. In Heraklion area, a series of projects in coastal zone are proposed to be implemented, by different stakeholders operating in the area. The methodology follows, a holistic decision making procedure that include the analysis of alternatives, categorisation and quantification of the consequences and implementation of trade-offs, aiming to introduce a method to assess the interactions between future land and sea uses, identify the land and sea uses interactions by quantifying the consequences of each intervention.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 March 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management〈/p〉 〈p〉Author(s): Qinhua Fang, Deqiang Ma, Liyu Zhang, Shouqin Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Xiamen has marked its integrated coastal management (ICM) practice as PEMSEA's demonstration site since the 1990s. However, the role of Marine Functional Zoning (MFZ) in ICM has not yet been fully explored even though the planning process has been highlighted in some literature on Xiamen ICM mode. To showcase the contribution of MFZ as a practical approach for Xiamen ICM, the five dimensions of integration in ICM is applied as an analysis framework. Firstly, through compiling of the historical data and documents of the sea uses and marine environments, and socioeconomic status as well, the key drivers of initiating MFZ in the 1990s is summarized as increasing but incompatible and even conflicting sea uses, degrading marine environments due to negative effects of intensified human activities, and the lack of coordinating mechanism which has worsened the use-use and use-environment conflicts. Secondly, the technical guidelines and adaptive evolvement of Xiamen MFZ is introduced, and the achievements of Xiamen MFZ is explored. Based on the above analysis, the relationships of MFZ and ICM is looked into the dimensions of legislation, coordinating mechanism, scientific and technical support, integrated law enforcement and public participation; and how MFZ contributes to ICM in integration of dimensions of intergovernmental, inter-sectoral, land and sea, science and management, and multiple disciplinary is analyzed in-depth. It is concluded that MFZ has been a working approach in Xiamen to realize ICM from a conceptual call to a good practice on the ground, even challenges remain.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 March 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management〈/p〉 〈p〉Author(s): Yaling Huang, Jinliang Huang, Ayu Ervinia, Shuiwang Duan, Sujay S. Kaushal〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding how land use and climate variability interact could amplify riverine nitrogen exports is needed to develop effective watershed management strategies in coastal China, a region that is experiencing the most rapid urbanization globally. We investigated the interactive effects of land use and climate variability on riverine nitrogen exports. We analyzed long-term historical data (1961–2014) in two river reaches of the Jiulong River Watershed and spatial data (2010–2014) across a land use gradient spanning 17 monitored headwater streams. Results showed that annual riverine nitrate-N (NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉-N) and ammonia-N (NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉-N) exports have significantly increased from 1961 to 2014 coinciding with urban expansion. Nitrate-N exports were correlated with river flow during 1961–1980, while they were not correlated with river flow during 1981–2002 when fertilizer use rapidly increased in this region. Nitrate-N export was tightly correlated with river flow during 2010–2014 as fertilizer use decreased and there was conversion of agricultural lands to urban lands. Annual NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉-N and NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉-N exports for 17 headwater streams across land use showed significant inter-annual variability (2–10 times) during 2010–2014 across dry and wet years. There was greater inter-annual variability in N exports at the urban/agricultural sites than at the forest sites. Urban watersheds had the highest runoff and nitrate-N export during the flood season. Runoff was the “master variable” controlling nitrate export in urban watersheds across time and space. Given rapid urbanization, the interaction between climate variability and land use change can amplify river nitrogen loads and coastal water quality issues in the developing world unless more effective management of the watershed and associated riverine system is applied.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 166〈/p〉 〈p〉Author(s): Dorota Ciołek, Magdalena Matczak, Joanna Piwowarczyk, Marcin Rakowski, Kazimierz Szefler, Jacek Zaucha〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents the results of a face-to-face survey of the attitudes of Polish fishermen towards Maritime Spatial Planning (MSP). Fishermen's self-assessed knowledge regarding MSP and their expectations were analysed. The conclusion reached shows that, despite similar access to information about MSP, Polish fishermen are less knowledgeable, more sceptical and more fearful of the MSP, than the other stakeholders involved. As a result, better education or more information on MSP would not suffice in making fishermen overcome their scepticism on the planning outcomes. In addition, the governing bodies of MSP should build trust and awareness, stimulate the stakeholders' interests in MSP, and convince the fishermen that MSP is friendly towards this specific sector. These findings did influence the MSP process in Poland, wherein MSP outreach was offered to the targeted groups of fishermen in the form of trust-building measures. A key lesson learned is that a capacity building process should be administered in such a way that the fishermen may easily distinguish it from other governance measures (e.g. under fishery or environment policy). An international component can play an important role in it. In conclusion, a number of observations are proposed with regard to future research on the attitudes of fishermen towards MSP. In particular, greater effort is necessary to better understand the motives of fishermen's scepticism towards the impact of MSP on their sector.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 165〈/p〉 〈p〉Author(s): Lea T. Mamo, Brendan P. Kelaher, Melinda A. Coleman, Patrick G. Dwyer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Increased coastal development and rising sea levels as a result of continuing climate-change put coastal regions at risk from flooding and inundation. A common mitigation response is the construction and upgrade of hard coastal protection structures, such as breakwaters, seawalls, and groynes. The alteration of the coast, together with the introduction of novel materials into coastal waters can negatively impact adjacent habitats and associated organisms. The implementation of management plans that involve scientists, as well as a variety of other stakeholders offer an opportunity to minimise adverse effects to biodiversity or even enhance it, while still protecting infrastructure and people. This study examines the management of an Australian breakwater upgrade and the progressive design finding process, including stakeholder engagement, determination of assessment criteria, and environmental impact assessment. In the course of the latter, scientific research led to the rediscovery of a presumed extinct algal species, 〈em〉Nereia lophocladia〈/em〉, which created an additional challenge and temporarily halted the upgrade. To accommodate this, the breakwater design solution was modified to avoid any impacts on the algal population and, in order to maximise the species' survival, novel ecological engineering approaches were proposed as mitigation strategies. Our case study underpins the value of evidence-based conservation and cooperation among stakeholders as important tools for minimising ecological impacts from coastal infrastructure upgrades.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 165〈/p〉 〈p〉Author(s): Idrissa Diedhiou, Zhengyong Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In 2016, Senegal's fisheries contributed 14.63% of total value of export earnings, representing 3.2% of Gross Domestic Product and employed an estimated 600,000 people, of which 30% were women. It is very important for Senegal to establish an effective policy system and protect its valuable fisheries resources. To realize this goal, scientists, government officials, and related parties should critically reflect upon fisheries policies and their performance. Given the high institutional instability in the country, this paper discusses the various policies adopted during different Senegalese political regimes, their evolution, and their implementation. This study also assesses how these policies impacted the availability of fishery resources in the country, and changed fishermen's behavior and income. We find that although some policies are effective, the overall policy system is still in dire need to be improved, as fisheries are still experiencing a downward trend due to illegal fishing and overfishing. We also find that the motorization of pirogues contributed to increasing the catch volumes and the extension of fishing areas. However, the signs of declining volumes of landings noted in the 1981s prompted the authorities to take advantage of specific management measures and regulations for the protection and restoration of habitats and overexploited marine resources. We propose a model of policy formulation based on stakeholder theory that deals realistically with issues of over-exploitation and illegal fishing, where all the interested parties should strongly participate in the decision-making process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 165〈/p〉 〈p〉Author(s): Marilena Papageorgiou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Underwater Cultural Heritage (hereinafter UCH) constitutes an invaluable resource that has been poorly – if at all – addressed in most spatial planning attempts, due to the sectorial approach that has prevailed so far when planning in the sea. Lately however, that spatial planning in the marine space (MSP) is being re-launched under a place-based approach, the chances and challenges for UCH are considerably different.〈/p〉 〈p〉According to the existing international legislation (UNCLOS), coastal states can only interfere with UCH up to their Contiguous Zone (24 nm from the baseline), whilst beyond that limit UCH is left “abandoned” (unless “flag” or “cultural origin” states claim their protection). Of course, this “freezing” of jurisdictions beyond the CZ, means that for the greatest part of the oceans and seas, UCH protection totally depends on the wise regulation of all other human activities that affect directly or indirectly, cultural heritage.〈/p〉 〈p〉The paper argues that MSP under a place-based approach is a unique opportunity for better protection and wiser management of UCH in greater distances than ever, provided that coastal states proclaim their EEZ (in order to extend as much as possible the area within which they can practice MSP and therefore, tackle conflicts and encourage synergies with UCH). The paper proposes a five-step strategy for considering UCH in MSP. Step 1: Register and evaluate UCH sites and objects, Step 2: Identify ways to upgrade the economic value of UCH, Step 3: Select the most appropriate type of protection zoning, Step 4: Provide regulations and restrictions for activities within the UCH protection zone, Step 5: Ensure integration and cohesion of the planning adopted in the UCH buffer zones with the spatial/sea-use planning adopted in the wider marine area. The paper concludes by highlighting that beyond any strategy, the greater challenge and stake is how to compromise blue growth trend with UCH preservation and promotion.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 167〈/p〉 〈p〉Author(s): Stephan R. Kolian, Michael Godec, Paul W. Sammarco〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The number of fixed oil and gas platforms are declining in the Gulf of Mexico, there were ∼3674 platforms installed the since 1942 and today there are ∼1320. Eventually, ∼30,000 jobs will be lost in related industries because of platform removals. Retired oil and gas platforms could be redeployed for alternate uses such as CO〈sub〉2〈/sub〉 capture and storage, renewable wind energy, and sustainable fisheries and employ citizens in coastal areas. Elsewhere around the world, offshore platforms are used for purposes other than producing oil and gas. U.S. Federal legislation (Energy Policy Act 2005 Section 388 of Public Law [PL] 109-58); 30 CFR 285.1000 Subpart J) authorizes the use of retired oil and gas platforms for alternate uses. If the retired oil and gas structures are preserved, the infrastructure could also be used to recover stranded petroleum using CO〈sub〉2〈/sub〉 enhanced oil recovery (CO〈sub〉2〈/sub〉-EOR). We examined the socio-economic incentives, environmental impacts, and regulatory issues associated with the alternate uses. We suggest that CO〈sub〉2〈/sub〉-EOR is the most economically efficient way to store CO〈sub〉2〈/sub〉 offshore and that offshore wind turbines may assist with the energy requirements for oil and gas production and CO〈sub〉2〈/sub〉-EOR. Data suggest that in our study area offshore platforms are more successful at producing fish and invertebrates if they are left standing instead of toppled over. The greatest regulatory issue facing the use of retired platforms is the transfer of liability. If the structures are redeployed, the previous oil and gas owner/operators are still responsible for eventual removal and catastrophic events. A variety of future economic activity in the Gulf of Mexico could take advantage of this infrastructure, if it remains in place.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 166〈/p〉 〈p〉Author(s): Carlos J. González, Alfredo Izquierdo, Óscar Álvarez, Miguel Bruno, Rafael Mañanes, Ivone A. Czerwinski, Francisco P. Zurita〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Metocean modeling resources from an operational oceanography system are applied to assess the hazard of bacterial contamination, resulting from domestic/industrial wastewater discharged into potential bivalve mollusk harvesting areas in Cadiz Bay (Andalusia). The proposed methodology is aimed to at meeting the European Union regulations and best practices for the management and monitoring of this harvesting activity. Modeled current fields, corresponding to scenarios with different wind and tidal conditions, are incorporated in a Lagrangian particle-tracking model, specifically designed to simulate the fate of the bacterial content of wastewaters discharged into the Bay. Numerical results are used to obtain various indices of occurrence and hazard maps of fecal contamination in seawater. The proposed indices also allow estimating fecal contamination fields if appropriate information of discharges and bacterial loads of the wastewater sources are available. Qualitative validation of results shows considerable agreement with measured contamination patterns. The areas with highest exposure to bacterial contamination are the Sancti Petri Channel and the central region of the Inner Bay, although a substantial variability depending on wind conditions is found. Unauthorized occasional wastewater discharges have a considerable impact on local water quality, while regulated wastewater sources are responsible for the larger-scale bacterial contamination pattern. The methodology developed is exportable to other environments and coastal management activities.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 166〈/p〉 〈p〉Author(s): M. Le Tixerant, D. Le Guyader, F. Gourmelon, B. Queffelec〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Although the importance of Maritime Spatial Planning (MSP) as a concept is know acknowledged and the legal framework is in place, the task of applying it remains a delicate one. One of the keys to success is having pertinent data. Knowing how maritime uses unfold in a spatio-temporal context, and what conflicting or synergistic interactions exist between activities, is crucial. However, this information is especially hard to obtain in a marine environment. As a result this information has often been identified as the missing layer in information systems developed by maritime stakeholders. Since 2002, the Automatic Identification System (AIS) has been undergoing a major development. Allowing for real time geo-tracking and identification for equipped vessels, the data that issues from AIS data promises to map and describe certain marine human activities.〈/p〉 〈p〉After recapitulating the main characteristics of AIS and the data it provides, this article proposes to evaluate how AIS is currently used in MSP at a European level, and to concisely present a series of methods and results obtained within the framework of several operational research projects. The objective is to illustrate how the AIS data processing and analysis can produce adequate information for MSP: maritime traffic density, shipping lanes and navigation flows, hierarchical network of maritime routes, alleged fishing zones, spatio-temporal interactions between activities (potential conflicting uses or synergies). The conclusion looks in particular at the legal questions concerning the use of AIS.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 165〈/p〉 〈p〉Author(s): Luis Outeiro, Sebastián Villasante, Rashid Sumaila〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Small-scale fisheries (SSFs) are complex social-ecological systems that are affected not only by biological responses to oceanographic changes but also by socio-economic conditions and market demand expressed from local to global scales. Ex-vessel prices are generally elastic and volatile from year to year or even from season to season, depending on many factors. This variability makes it difficult to keep fishers' incomes and livelihoods stable over time. Here, we use a multispecies small-scale fishery from the 〈em〉Ria de Arousa〈/em〉 (NW Spain) as an example to illustrate the complexity and economic contributions of SSFs and to analyse the performance of SSFs in terms of net income per fisher. Our results show that the mean total landed value from SSFs is approximately 35 million US$·year〈sup〉−1〈/sup〉, which represents almost 25% of the total annual value of Spanish SSF landings and almost 4% of the value of European Union SSF landings. Our study reveals that from 2008 to 2014, the total landed value of the fishing fleet operating in the area has decreased by 11.8 million US$·year〈sup〉−1〈/sup〉, a decrease of 18.8% within the seven-year study period. The study also indicates that floating shellfisheries are by far the type of fishing gear that generates the largest total landings and landed value in the 〈em〉Ria de Arousa,〈/em〉 generating a mean revenue of 19.66 million US$·year〈sup〉−1〈/sup〉. The total economic weight of floating shellfisheries together with the high distribution of licenses provides license holders with year-round economic stability. The combination of the number of fishing gear selected and the number of species that generate their revenues plays an important role in shaping fishers' ability to obtain an income from SSFs. Nevertheless, high dependence on and specialisation in shellfisheries could reduce fishers' social-ecological resilience and hamper their ability to cope with uncertain natural dynamics in changing ecosystems. We find that the net income per fisher varies between 4,000 and 42,000 US$·year〈sup〉−1〈/sup〉, with a mean net income per fisher of 21,800 US$·year〈sup〉−1〈/sup〉. Taking into account the Spanish minimum wage, almost 40% of fishers in the study area earn at least the minimum wage, 8% earn almost double the minimum wage, and 1.4% make three times the minimum wage. From a global perspective, we found that only three out of the 33 countries analysed present fishers' net incomes that are above or almost equal to the national average wage and far above each country's minimum wage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 June 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management〈/p〉 〈p〉Author(s): Pascal Dumas, Suzanne C. Mills, Grégoire Moutardier, Sompert Gereva, Ricardo Beldade, Jayven Ham, Rocky Kaku, Mehdi Adjeroud〈/p〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 166〈/p〉 〈p〉Author(s): A. Giorgetti, E. Partescano, A. Barth, L. Buga, J. Gatti, G. Giorgi, A. Iona, M. Lipizer, N. Holdsworth, M.M. Larsen, D. Schaap, M. Vinci, M. Wenzer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Scientific research as well as management of the marine environment, and sustainable blue growth are based on the availability of quality-assured observations, reliable data and solid scientific-based information. These represent three consecutive steps of Data-Information-Knowledge-Wisdom paradigm on the pyramid of wisdom, providing different layers of information. EMODnet (European Marine Observation and Data network) is one of the key infrastructures engaged in collecting, facilitating access and promoting use and re-use of marine observation and data products for both scientific research and marine environmental management. Its Spatial Data Infrastructure (SDI) represents a powerful mechanism to support the implementation of the Marine Strategy Framework Directive Article 19.3 in accordance with the INSPIRE Directive standards and implementing rules. Standardized, harmonized and validated chemical data collections are made available for water quality evaluation at a regional scale, establishing interoperability between the data sets from the many different providers (more than 60 in EMODnet Chemistry). Concentration maps of nutrients, chlorophyll-a and dissolved oxygen are computed on a standard grid, providing information at a regular time interval, per season and over several vertical layers, including the deepest one. Dedicated Open Geospatial Consortium standard services for browsing, viewing and downloading chemistry observation data and data products for the European waters have been developed, and are actively maintained and monitored. These results can provide knowledge layers and can also answer the needs of the directive on Maritime Spatial Planning (EU, 2014), which requires the integration of multidisciplinary data and information on the state of the marine environment with maritime and human activities.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean & Coastal Management, Volume 165〈/p〉 〈p〉Author(s): Shengle Yin, Aigo Takeshige, Yoichi Miyake, Shingo Kimura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The coastal areas are subject to increasing exploitation and diverse functions. The widely conducted aquaculture activities intensify the stress at the coastal areas and bring new challenges to aquaculture and sustainable coastal management. The suitable site selection is an optimistic way to minimizing stress on ecosystem, enhancing productive harvests, and mitigating conflicts between different water users. This study aims to demonstrate a local-oriented approach for selecting suitable locations for mussel cultivation in the Menai Strait by conducting Multi-Criteria Decision Analysis (MCDA), which takes environmental and socio-economic factors into consideration. A high resolution hydrodynamic model was built to overcome data scarcity by providing data sets. Interviews and a questionnaire survey were organized to engage local stakeholders into decision-making process. The result suggested two separated areas that suitable for mussel cultivation, which covers 20.5% of the whole region (8.8 km〈sup〉2〈/sup〉). The environmentally productive area differed significantly from socio-economically suitable area, which indicated that both categories of evaluation criteria need to be concurrently considered to achieve high production as well as prevent conflicts among stakeholders. This selection method provides a way to overcome data scarcity and engage local stakeholders, and its implementation has the potential to contribute to the sustainable coastal development by reducing potential conflicts among users at the planning stage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): Shitao Wang, Guotu Li, Mohamed Iskandarani, Matthieu Le Hénaff, Omar M. Knio〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present an analysis of two recent efforts aimed at quantifying the uncertainties in a 30-day HYbrid Coordinate Ocean Model forecast of the circulation in the Gulf of Mexico, with particular emphasis on the separation of Loop Current Eddy Franklin, using Polynomial Chaos methods. The analysis herein explores whether the model perturbations lead to realistic representation of the uncertainty in the Gulf Circulation. Comparisons of model output with Sea Surface Height and current mooring data show that the observational data generally falls within the envelope of the ensemble and that the modal decomposition delivers “realistic” perturbations in the Loop Current region. We use information theory metrics to quantify the information gain and the computational trade-offs between different wind and initial conditions perturbation modes. The relative entropy measures indicate that two modes for initial condition perturbations are enough, in our model configuration, to represent the uncertainty in the Loop Current region; while two modes for wind forcing perturbations are necessary in order to estimate the uncertainty in the coastal zone. The ensemble statistics are then explored using the Polynomial Chaos surrogate and the newly developed contour boxplot methods.〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 132〈/p〉 〈p〉Author(s): Renhao Wu, Zhiting Jiang, Chunyan Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A complex archipelago exhibits high velocity shear, strong advection, and significant nonlinearity for tides, overtides, tidal currents, and subtidal hydrodynamics. Here, a high-resolution regional ocean modeling system with two-way nesting is applied to the coastal Zhoushan Archipelago in the East China Sea. After validation for the M〈sub〉2〈/sub〉, S〈sub〉2〈/sub〉, K〈sub〉1〈/sub〉, and O〈sub〉1〈/sub〉 tidal constituents, the spatial structures of tides and tidal currents are presented. The features of these constituents and two significant overtides of M〈sub〉2〈/sub〉 (M〈sub〉4〈/sub〉 and M〈sub〉6〈/sub〉) are discussed. The M〈sub〉2〈/sub〉 tide is dominant in the study domain, followed by the S〈sub〉2〈/sub〉, K〈sub〉1〈/sub〉, and O〈sub〉1〈/sub〉 tides in amplitude in that order. Tidal energy budget analysis shows that about 46.4% of the incoming energy is dissipated inside the study area and 67.3% of the dissipated energy is consumed by the bottom friction, while the remainder passes through the study domain. Jetlike flows in the channels are among the most remarkable features. Analysis of momentum balance terms averaged over the flood or ebb period demonstrates that the primary balance near the islands is between the horizontal advection and the pressure gradient force, suggesting a predominant Bernoulli-type motion with strong nonlinearity. However, in the area away from the islands, the horizontal advection becomes less important. The M〈sub〉4〈/sub〉 and M〈sub〉6〈/sub〉 tides are mainly generated by nonlinear advection, bottom friction plays a minor role, and the interactions between different constituents also have some influence.〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): Gabriela S. Pilo, Peter R. Oke, Richard Coleman, Tatiana Rykova, Ken Ridgway〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is expected that the assimilation of data in an ocean model disrupts the model’s dynamical balance. This disruption occurs because the analysis fields are not a precise solution to the equations of the model. Therefore, the model adjusts to the applied increments. With this limitation in mind, we assess the impact of sequential data assimilation (DA) on vertical velocity - chosen because of its sensitivity to model dynamical balances. We investigate vertical velocity within mesoscale eddies in the Tasman Sea and off Tasmania, Australia in an ocean reanalysis that assimilates observations every four days. In a free-running model, with no DA, ocean eddies often show a coherent pattern of alternating upward and downward cells. These cells are induced by eddy distortion (i.e., the eddy becoming more or less isotropic). In this study, we aim to first determine if a data-assimilating model can reproduce these alternating upward and downward cells; and then to investigate how the cells are affected by sequential DA. We view this study as a step towards better understanding the suitability of data-assimilating ocean models for detailed analysis of ocean circulation and ocean dynamics. We show that the vertical velocities are typically two times larger in magnitude on the day after assimilation, compared to subsequent days. Despite the model adjustment, the alternating upward and downward cells are present in the data-assimilating model. In fact, we find that the model adjustment acts like an artificial eddy distortion on the first day after assimilation - when the model is adjusting to the applied increments - amplifying the vertical velocities within the eddies. This artificial distortion impacts temperature and salinity, through vertical advection. The vertical advection terms are about 1.5 times higher on the day after assimilation, compared to other days. The temperature and salinity changes resulting from the stronger vertical advection are mostly 2–10 times smaller than the increments of these properties applied during assimilation. Our findings suggest that a data-assimilating model may be useful for investigating the detailed dynamics of the ocean, but care should be taken when interpreting results. Moreover, we suggest that it is prudent to disregard the model’s fields within the first day after assimilation - particularly in analyses of dynamical balances.〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): Renhao Wu, Han Zhang, Dake Chen, Chunyan Li, Jianmin Lin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A fully coupled atmosphere-ocean-wave model is applied to study the upper ocean response of the South China Sea (SCS) to Typhoon Kalmaegi. The model results are validated by satellite observations and in situ observations at four stations. The coupled model system reproduces the air-sea thermal and dynamic features. Typhoon Kalmaegi passed through the SCS with a mean translation speed of approximately 8.0 m s〈sup〉−1〈/sup〉, a fast-moving storm with a predominantly baroclinic ocean response. The results show some typhoon-induced rightward intensifications in sea surface cooling, current speed, and significant wave height. They also show inertial pumping with alternating upwelling and downwelling, and strong isotherm and current oscillations with near-inertial frequencies. Some remarkable ocean responses are also found: (1) a significant cooling occurred in the northern SCS slope and shelf regions; and (2) the storm induced a near-inertial internal wave propagating in the track direction, where the wave crest impinged the slope and climbed up the shelf. A two-layer ocean current response and strong mixing at the slope bottom induced by breaking waves are also observed. A heat budget analysis shows that the vertical diffusion dominates the rate of change of temperature in the upper layer, while the total advection plays a major role in the subsurface layer. The net surface heat flux makes a minor contribution to cooling in the upper layer on the right side of the storm's track. In contrast, its contribution to the surface layer cooling on the left side is comparable to that of the vertical diffusion terms, indicating that surface heat fluxes cannot be ignored in this region.〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): Hiroyuki Tsujino, Shiro Nishikawa, Kei Sakamoto, Hideyuki Nakano, Hiroshi Ishizaki〈/p〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 132〈/p〉 〈p〉Author(s): F. Auclair, L. Bordois, Y. Dossmann, T. Duhaut, A. Paci, C. Ulses, C. Nguyen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉A three-mode time-split algorithm is proposed to simulate non-hydrostatic ocean processes in a natural way: fast pressure adjustments via acoustic waves are explicitly represented. The full set of compressible Navier–Stokes equations is integrated for a free-surface ocean with three time-steps respectively associated to the internal, external and compressible (non Boussinesq) modes. The resulting three-mode algorithm can be implemented either in a fully compressible configuration or in a “pseudo-compressible” configuration by artificially lowering acoustic-wave velocities to reduce computational costs. The present description of the three-mode algorithm focuses in the first place on the simulation of non-hydrostatic processes in free-surface ocean models.〈/p〉 〈p〉Several test simulations related to linear and non-linear acoustic, surface and internal gravity waves are studied in details with the proposed three-mode algorithm.〈/p〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): E.V. Stanev, J. Pein, S. Grashorn, Y. Zhang, C. Schrum〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM), which uses unstructured grids, is set up for the North and Baltic Seas. With a resolution of ∼100 m in the narrow straits connecting the two basins, this model accurately resolves the inter-basin exchange. Validation against observations in the straits shows the model has good skill in simulating the transport and vertical profiles of temperature, salinity and currents. The timing and magnitude of the major inflow event in 2014–2015 is also realistically simulated. The analysis is focused on the two-layer exchange, its dependence on the atmospheric forcing, and dominant physical balances. The two-layer flows in the three connecting straits show different dependencies upon the net transport. The spatial variability of this dependence is also quite pronounced. The three-strait system developed specific dynamics, with time lags and differences between currents in the individual straits during inflow and outflow conditions. Analysis on the impact of resolution indicates that the performance of the model changes depending on whether the narrow parts of the straits are resolved with a resolution of 500 m or 100 m. With this ultra-fine resolution, gravity flows and variability of salinity in deep layers is generally more adequately simulated. This paper identifies the needs for more profound analysis of the coupled dynamics of Baltic and North Seas with a focus on the Danish straits.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 133〈/p〉 〈p〉Author(s): Alfredo Izquierdo, Uwe Mikolajewicz〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The impact of tides on the spreading of the Mediterranean Outflow Waters (MOW) in the Gulf of Cadiz is investigated through a series of targeted numerical experiments using an ocean general circulation model. The full ephimeridic luni-solar tidal potential is included as forcing. The model grid is global with a strong zoom around the Iberian Peninsula. Thus, the interaction of processes of different space and time scales, which are involved in the MOW spreading, is enabled. This is of particular importance in the Strait of Gibraltar and the Gulf of Cádiz, where the width of the MOW plume is a few tens of km. The experiment with enabled tides successfully simulates the main tidal features of the North Atlantic and in the Gulf of Cádiz and the Strait of Gibraltar. The comparison of the fields from simulations with and without tidal forcing shows drastically different MOW pathways in the Gulf of Cádiz: The experiment without tides shows an excessive southwestward spreading of Mediterranean Waters along the North African slope, whereas the run with tides is closer to climatology. A detailed analysis indicates that tidal residual currents in the Gulf of Cádiz are the main cause for these differences.〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 131〈/p〉 〈p〉Author(s): Xin Zhao, Hayley H. Shen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A three-layer model is presented to simulate gravity wave propagation in an ice-covered sea. Damping from a viscoelastic ice cover and the boundary layer of the water body are considered. This model is shown to converge to three previous models: viscoelastic ice over inviscid water, thin elastic plate over viscous water, and viscous ice over viscous water. The non-monotonic attenuation with respect to the wave period shown previously in the thin elastic plate over viscous water also appears in the proposed model. Sensitivity analysis indicated no significant influence of the thickness of the boundary layer modeled with an eddy viscosity on either the wave dispersion or the attenuation, but a significant effect on wave attenuation from the eddy viscosity. Based on a consistent formulation for a three-layer system, we provide a compact model that combines dissipation from the ice cover and the boundary layer underneath, as well as the associated wave dispersion.〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Ocean Modelling, Volume 132〈/p〉 〈p〉Author(s): Yongquan Li, Haibo Chen, Xianqing Lv〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Based on a validated underwater oil spill model and the hydrodynamic background provided by an unstructured grid, finite-volume, coastal ocean model (FVCOM), a series of numerical experiments are conducted to study the impact of error in ocean dynamical background currents on the 3D transport of underwater spilled oil, in terms of three metrics including oil centroid position, sweeping area, and sweeping volume. Numerical result shows that a larger error in ocean dynamical background currents results in a larger model error expectation and uncertainty for all three metrics. As model time increases, the model error mainly increases and the error growth rate varies unevenly. The sensitivity of the oil spill model to background current error can be interpreted as an integrated result of the temporal and spatial variations of the background current and the movement of oil droplets of different sizes.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 CATENA, Volume 172〈/p〉 〈p〉Author(s): Xing Jian, Wei Zhang, Hanghai Liang, Ping Guan, Ling Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Weathering, as an important process in the earth surface system, can be significantly influenced by tectonics and climates over long time scales. Here, we use mineralogical, petrographic and geochemical data of a paleoweathering profile developed on basement granodioritic rocks of northern Qaidam basin, northern Tibet, to reconstruct early Eocene weathering conditions and to discuss how paleoclimates and tectonics dominated the weathering process. The results indicate that neoformed mineral phases in weathering products are dominated by smectite, and the profile has overwhelmingly low chemical index of alteration values (ca. 51–59) and significantly decreasing micropetrographic index values (from 25.0 to 0.2) from bottom to top. These findings suggest that the basement rocks experienced mild chemical weathering but relatively intensive physical weathering. We favor that non-steady-state weathering, in which mechanical erosion rates compare favorably with rates of chemical weathering, prevailed in northern Tibet during the early Eocene. The weathering conditions were likely an integrated response to active tectonism and dry climates at that time. Furthermore, chemical element mobility evaluation demonstrates that most of large ion lithophile elements and light rare earth elements (LREEs) of granodioritic rocks are quite active during weathering and can be easily leached even under mild chemical weathering conditions. Significant mass loss of Al and LREEs in upper weathered samples probably reflects acidic weathering conditions, which were likely due to extremely high atmospheric CO〈sub〉2〈/sub〉 level during the early Eocene. This study, from the unique perspective of weathering process, suggests that intensive deformation and rapid tectonic erosion occurred in northern Tibet during the early Eocene, as a far-field response to the India-Eurasia collision. It also agrees with warm and relatively dry climates, which were likely attributed to the global greenhouse climates and the Paleogene planetary-wind-dominant climate system in Asia, respectively.〈/p〉〈/div〉 〈/div〉