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  • Other Sources  (949)
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  • 1
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    Optimised use of data fusion and memory‐based learning with an Austrian soil library for predictions with infrared data (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Infrared spectroscopy in the visible to near‐infrared (vis–NIR) and mid‐infrared (MIR) regions is a well‐established approach for the prediction of soil properties. Different data fusion and training approaches exist, and the optimal procedures are yet undefined and may depend on the heterogeneity present in the set and on the considered scale. The objectives were to test the usefulness of partial least squares regressions (PLSRs) for soil organic carbon (SOC), total carbon (C〈sub〉t〈/sub〉), total nitrogen (N〈sub〉t〈/sub〉) and pH using vis–NIR and MIR spectroscopy for an independent validation after standard calibration (use of a general PLSR model) or using memory‐based learning (MBL) with and without spiking for a national spectral database. Data fusion approaches were simple concatenation of spectra, outer product analysis (OPA) and model averaging. In total, 481 soils from an Austrian forest soil archive were measured in the vis–NIR and MIR regions, and regressions were calculated. Fivefold calibration‐validation approaches were carried out with a region‐related split of spectra to implement independent validations with n ranging from 47 to 99 soils in different folds. MIR predictions were generally superior over vis–NIR predictions. For all properties, optimal predictions were obtained with data fusion, with OPA and spectra concatenation outperforming model averaging. The greatest robustness of performance was found for OPA and MBL with spiking with 〈italic toggle="no"〉R〈/italic〉〈sup〉2〈/sup〉 ≥ 0.77 (N), 0.85 (SOC), 0.86 (pH) and 0.88 (C〈sub〉t〈/sub〉) in the validations of all folds. Overall, the results indicate that the combination of OPA for vis–NIR and MIR spectra with MBL and spiking has a high potential to accurately estimate properties when using large‐scale soil spectral libraries as reference data. However, the reduction of cost‐effectiveness using two spectrometers needs to be weighed against the potential increase in accuracy compared to a single MIR spectroscopy approach.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:631.4 ; data fusion ; independent validation ; infrared spectroscopy ; MBL ; nitrogen ; outer product analysis ; pH ; soil organic carbon ; spiking ; total carbon
    Language: English
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  • 2
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    Vertical SOC distribution and aromatic carbon in centuries old charcoal‐rich Technosols (2022)
    Bonhage, Alexander ; Raab, Thomas ; Schneider, Anna ; [et al.]
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-01-21
    Description: Charcoal‐rich Technosols on century‐old relict charcoal hearths (RCHs) are the subject of ongoing research regarding potential legacy effects that result from historic charcoal production and subsequent charcoal amendments on forest soil properties and forest ecosystems today. RCHs consist mostly of Auh horizons that are substantially enriched in soil organic carbon (SOC), of which the largest part seems to be of pyrogenic origin (PyC). However, the reported range of SOC and PyC contents in RCH soil also suggests that they are enriched in nonpyrogenic SOC. RCH soils are discussed as potential benchmarks for the long‐term influence of biochar amendment and the post‐wildfire influences on soil properties. In this study, we utilised a large soil sample dataset (n = 1245) from 52 RCH sites in north‐western Connecticut, USA, to quantify SOC contents by total element analysis. The contents of condensed highly aromatic carbon as a proxy for black carbon (BC) were predicted by using a modified benzene polycarboxylated acid (BPCA) marker method in combination with diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy‐based partial least square regression (r2 = 0.89). A high vertical spatial sampling resolution allowed the identification of soil organic matter (SOM) enrichment and translocation processes. The results show an average 75% and 1862% increase in TOC and BPCA‐derived carbon, respectively, for technogenic Auh horizons compared to reference soils. In addition to an increase in aromatic properties, increased carboxylic properties of the RCH SOC suggest self‐humification effects of degrading charcoal and thereby the continuing formation of leachable aromatic carbon compounds, which could have effects on pedogenic processes in buried soils. Indeed, we show BPCA‐derived carbon concentrations in intermediate technogenic Cu horizons and buried top/subsoils that suggest vertical translocation of highly aromatic carbon originating in RCH Auh horizons. Topmost Auh horizons showed a gradual decrease in total organic carbon (TOC) contents with increasing depth, suggesting accumulation of recent, non‐pyrogenic SOM. Lower aliphatic absorptions in RCH soil spectra suggest different SOM turnover dynamics compared to reference soils. Furthermore, studied RCH soils featured additional TOC enrichment, which cannot be fully explained now. Highlights BC to TOC ratio and high resolution vertical SOC distribution in 52 RCH sites were studied. RCH soils non‐BC pool was potentially different to reference soils. RCH soils feature TOC accumulation in the topmost horizon. There is BC translocation into buried soils on RCH sites.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:631.4 ; benzene polycarboxylated acid marker (BPCA) ; black carbon ; charcoal degradation ; charcoal kiln ; pyrogenic carbon ; relict charcoal hearth ; biochar
    Language: English
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  • 3
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    Potential erodibility of semi‐arid steppe soils derived from aggregate stability tests (2022)
    Koza, Moritz ; Pöhlitz, Julia ; Prays, Aleksey ; [et al.]
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-01-26
    Description: Erosion is a severe threat to the sustainable use of agricultural soils. However, the structural resistance of soil against the disruptive forces steppe soils experience under field conditions has not been investigated. Therefore, 132 topsoils under grass‐ and cropland covering a large range of physico‐chemical soil properties (sand: 2–76%, silt: 18–80%, clay: 6–30%, organic carbon: 7.3–64.2 g kg−1, inorganic carbon: 0.0–8.5 g kg−1, pH: 4.8–9.5, electrical conductivity: 32–946 μS cm−1) from northern Kazakhstan were assessed for their potential erodibility using several tests. An adjusted drop‐shatter method (low energy input of 60 Joule on a 250‐cm3 soil block) was used to estimate the stability of dry soil against weak mechanical forces, such as saltating particles striking the surface causing wind erosion. Three wetting treatments with various conditions and energies (fast wetting, slow wetting, and wet shaking) were applied to simulate different disruptive effects of water. Results indicate that aggregate stability was higher for grassland than cropland soils and declined with decreasing soil organic carbon content. The results of the drop‐shatter test suggested that 29% of the soils under cropland were at risk of wind erosion, but only 6% were at high risk (i.e. erodible fraction 〉60%). In contrast, the fast wetting treatment revealed that 54% of the samples were prone to become “very unstable” and 44% “unstable” during heavy rain or snowmelt events. Even under conditions comparable to light rain events or raindrop impact, 53–59% of the samples were “unstable.” Overall, cropland soils under semi‐arid conditions seem much more susceptible to water than wind erosion. Considering future projections of increasing precipitation in Kazakhstan, we conclude that the risk of water erosion is potentially underestimated and needs to be taken into account when developing sustainable land use strategies. Highlights Organic matter is the important binding agent enhancing aggregation in steppe topsoils. Tillage always declines aggregate stability even without soil organic carbon changes. All croplands soil are prone to wind or water erosion independent of their soil properties. Despite the semi‐arid conditions, erosion risk by water seems higher than by wind.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:631.4 ; climate change ; land use ; soil organic carbon ; soil texture ; water erosion ; wind erosion
    Language: English
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  • 4
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    Non‐exchangeable stable hydrogen isotope ratios in clay minerals and soil clay fractions: A method test (2022)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-01-20
    Description: Stable hydrogen isotope ratios (δ2H values) in structural hydroxyl groups of pedogenic clay minerals are inherited from the surrounding water at the time of their formation. Only non‐exchangeable H preserves the environmental forensic and paleoclimate information (δ2Hn value). To measure δ2Hn values in structural H of clay minerals and soil clay fractions, we adapted a steam equilibration method by accounting for high hygroscopicity. Our δ2Hn values for USGS57 biotite (−95.3 ± SD 0.9‰) and USGS58 muscovite (30.7 ± 1.4‰) differed slightly but significantly from the reported δ2H values (−91.5 ± 2.4‰ and −28.4 ± 1.6‰), because the minerals contained 1.1%–4.4% of exchangeable H. The low SD of replicate measurements (n = 3) confirmed a high precision. The clay separation method including destruction of Fe oxides, carbonates and soil organic matter, and dispersion did not significantly change the δ2Hn values of five different clay minerals. However, we were unable to remove all organic matter from the soil clay fractions resulting in an estimated bias of 1‰ in two samples and 15‰ in the carbon‐richest sample. Our results demonstrate that δ2Hn values of structural H of clay minerals and soil clay fractions can be reliably measured without interference from atmospheric water and the method used to separate the soil clay fraction. Highlights We tested steam equilibration to determine stable isotope ratios of structural H in clay. Gas‐tight capsule sealing in Ar atmosphere was necessary to avoid remoistening. Our steam equilibration method showed a high accuracy and precision. The clay separation method did not change stable isotope ratios of structural H in clay.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:549 ; controlled isotope exchange technique ; deuterium ; montmorillonite ; soil clay separation ; soil organic matter removal ; steam equilibration ; structural H ; USGS57 biotite ; vermiculite ; δ2H
    Language: English
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  • 5
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    Importance of catchment hydrological processes and calibration of hydrological‐hydrodynamic rainfall‐runoff models in small rural catchments (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2024-01-19
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In recent years, many two‐dimensional (2D) hydrodynamic models have been extended to include the direct rainfall method (DRM). This allows their application as a hydrological‐hydrodynamic model for the determination of floodplains in one model system. In previous studies on DRM, the role of catchment hydrological processes (CaHyPro) and its interaction with the calibration process was not investigated in detail. In the present, case‐oriented study, the influence of the spatiotemporal distribution of the processes precipitation and runoff formation in combination with the 2D model HEC‐RAS is investigated. In a further step, a conceptual approach for event‐based interflow is integrated. The study is performed on the basis of a single storm event in a small rural catchment (low mountain range, 38 km〈sup〉2〈/sup〉) in Hesse (Germany). The model results are evaluated against six quality criteria and compared to a simplified baseline model. Finally, the calibrated improved model is contrasted with a calibrated baseline model. The results show the enhancement of the model results due to the integration of the CaHyPro and highlight its interplay with the calibrated model parameters.〈/p〉
    Keywords: ddc:551.48 ; 2D hydrodynamic modeling ; calibration ; direct rainfall modeling ; hydrological processes ; radar data ; runoff formation
    Language: English
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  • 6
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    Redoxtrons – An experimental system to study redox processes within the capillary fringe (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-11-18
    Description: Spatiotemporal characterisation of the soil redox status within the capillary fringe (CF) is a challenging task. Air‐filled porosities (ε), oxygen concentration (O〈sub〉2〈/sub〉) and soil redox potential (EH) are interrelated soil variables within active biogeochemical domains such as the CF. We investigated the impact of water table (WT) rise and drainage in an undisturbed topsoil and subsoil sample taken from a Calcaric Gleysol for a period of 46 days. We merged 1D (EH and matric potential) and 2D (O〈sub〉2〈/sub〉) systems to monitor at high spatiotemporal resolution redox dynamics within self‐constructed redoxtron housings and complemented the data set by a 3D pore network characterization using X‐ray microtomography (X‐ray μCT). Depletion of O〈sub〉2〈/sub〉 was faster in the organic matter‐ and clay‐rich aggregated topsoil and the CF extended 〉10 cm above the artificial WT. The homogeneous and less‐aggregated subsoil extended only 4 cm above the WT as indicated by ε–O〈sub〉2〈/sub〉–EH data during saturation. After drainage, 2D O〈sub〉2〈/sub〉 imaging revealed a fast aeration towards the lower depths of the topsoil, which agrees with the connected ε derived by X‐ray μCT (ε〈sub〉CT_conn〈/sub〉) of 14.9% of the total porosity. However, small‐scaled anoxic domains with O〈sub〉2〈/sub〉 saturation 〈5% were apparent even after lowering the WT (down to 0.25 cm〈sup〉2〈/sup〉 in size) for 23 days. These domains remained a nucleus for reducing soil conditions (E〈sub〉H〈/sub〉 〈 −100 mV), which made it challenging to characterise the soil redox status in the CF. In contrast, the subsoil aeration reached O〈sub〉2〈/sub〉 saturation after 8 days for the complete soil volume. Values of ε〈sub〉CT_conn〈/sub〉 around zero in the subsoil highlighted that soil aeration was independent of this parameter suggesting that other variables such as microbial activity must be considered when predicting the soil redox status from ε alone. The use of redoxtrons in combination with localised redox‐measurements and image based pore space analysis resulted in a better 2D/3D characterisation of the pore system and related O〈sub〉2〈/sub〉 transport properties. This allowed us to analyse the distribution and activity of microbiological niches highly associated with the spatiotemporal variable redox dynamics in soil environments. Highlights: The time needed to turn from reducing to oxidising (period where all platinum electrodes feature E〈sub〉H〈/sub〉 〉 300 mV) condition differ for two samples with contrasting soil structure. The subsoil with presumably low O〈sub〉2〈/sub〉 consumption rates aerated considerably faster than the topsoil and exclusively by O〈sub〉2〈/sub〉 diffusion through medium‐ and fine‐sized pores. To derive the soil redox status based upon the triplet ε–O〈sub〉2〈/sub〉–E〈sub〉H〈/sub〉 is challenging at present in heterogeneous soil domains and larger soil volumes than 250 cm〈sup〉3〈/sup〉. Undisturbed soil sampling along with 2D/3D redox measurement systems (e.g., redoxtrons) improve our understanding of redox dynamics within the capillary fringe.
    Keywords: ddc:631.4 ; environmental monitoring ; incubation experiments ; redox processes ; soil reducing conditions ; undisturbed soil ; X‐ray microtomography
    Language: English
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  • 7
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    The dilemma of analytical method changes for soil organic carbon in long‐term experiments (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-11-17
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈sec xmlns:mml="http://www.w3.org/1998/Math/MathML" id="ejss13362-sec-1003" xml:lang="en"〉 〈p xml:lang="en"〉Long‐term experiments (LTEs) have provided data to modellers and agronomists to investigate changes and dynamics of soil organic carbon (SOC) under different cropping systems. As treatment changes have occurred due to agricultural advancements, so too have analytical soil methods. This may lead to method bias over time, which could affect the robust interpretation of data and conclusions drawn. This study aims to quantify differences in SOC due to changes in dry combustion methods over time, using soil samples of a LTE established in 1963 that focuses on mineral and organic fertilizer management in the temperate zone of Northeast Germany. For this purpose, 1059 soil samples, collected between 1976 and 2008, have been analysed twice, once with their historical laboratory method right after sampling, and a second time in 2016 when all samples were analysed using the same elementary analyser. In 9 of 11 soil sampling campaigns, a paired 〈italic toggle="no"〉t〈/italic〉‐test provided evidence for significant differences in the historical SOC values when compared with the re‐analysed concentrations of the same LTE sample. In the sampling years 1988 and 2004, the historical analysis obtained about 0.9 g kg〈sup〉−1〈/sup〉 lower SOC compared with the re‐analysed one. For 1990 and 1998, this difference was about 0.4 g kg〈sup〉−1〈/sup〉. Correction factors, an approach often used to correct for different analytical techniques, could only be applied for 5 of 11 sampling campaigns to account for constant and proportional systematic method error. For this particular LTE, the interpretation of SOC changes due to agronomic management (here fertilization) deviates depending on the analytical method used, which may weaken the explanatory power of the historical data. We demonstrate that analytical method changes over time present one of many challenges in the interpretation of time series data of SOC dynamics. Therefore, LTE site managers need to ensure providing all necessary protocols and data in order to retrace method changes and if necessary recalculate SOC.〈/p〉 〈/sec〉〈sec xmlns:mml="http://www.w3.org/1998/Math/MathML" id="ejss13362-sec-0003" xml:lang="en"〉 〈title〉Highlights〈/title〉 〈p xml:lang="en"〉〈list list-type="bullet" id="ejss13362-list-0001"〉 〈list-item id="ejss13362-li-0001"〉〈p〉A total of 1059 LTE soil samples taken between 1976 and 2008 were re‐analysed for SOC in 2016〈/p〉〈/list-item〉 〈list-item id="ejss13362-li-0002"〉〈p〉Several methodological changes for SOC determination led to significant different SOC concentration in the same sample〈/p〉〈/list-item〉 〈list-item id="ejss13362-li-0003"〉〈p〉Interpretation and time series of LTE soil data suffer from consideration of analytical method changes and poor documentation of the same〈/p〉〈/list-item〉 〈list-item id="ejss13362-li-0004"〉〈p〉Soil archive establishment, thorough method protocols and diligent proficiency testing after soil method changes ameliorate the dilemma〈/p〉〈/list-item〉 〈/list〉〈/p〉 〈/sec〉
    Description: Brandenburger Staatsministerium für Wissenschaft, Forschung und Kultur http://dx.doi.org/10.13039/501100004581
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100004937
    Description: https://doi.org/10.4228/zalf-acge-b683
    Keywords: ddc:631.4 ; Bland–Altman ; carbon stocks ; data trueness ; Deming regression ; method bias ; soil archive ; soil survey
    Language: English
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  • 8
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    Toward an adequate level of detail in flood risk assessments (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2024-01-24
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Flood risk assessments require different disciplines to understand and model the underlying components hazard, exposure, and vulnerability. Many methods and data sets have been refined considerably to cover more details of spatial, temporal, or process information. We compile case studies indicating that refined methods and data have a considerable effect on the overall assessment of flood risk. But are these improvements worth the effort? The adequate level of detail is typically unknown and prioritization of improvements in a specific component is hampered by the lack of an overarching view on flood risk. Consequently, creating the dilemma of potentially being too greedy or too wasteful with the resources available for a risk assessment. A “sweet spot” between those two would use methods and data sets that cover all relevant known processes without using resources inefficiently. We provide three key questions as a qualitative guidance toward this “sweet spot.” For quantitative decision support, more overarching case studies in various contexts are needed to reveal the sensitivity of the overall flood risk to individual components. This could also support the anticipation of unforeseen events like the flood event in Germany and Belgium in 2021 and increase the reliability of flood risk assessments.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: BMBF http://dx.doi.org/10.13039/501100002347
    Description: Federal Environment Agency http://dx.doi.org/10.13039/501100010809
    Description: http://howas21.gfz-potsdam.de/howas21/
    Description: https://www.umwelt.niedersachsen.de/startseite/themen/wasser/hochwasser_amp_kustenschutz/hochwasserrisikomanagement_richtlinie/hochwassergefahren_und_hochwasserrisikokarten/hochwasserkarten-121920.html
    Description: https://download.geofabrik.de/europe/germany.html
    Description: https://emergency.copernicus.eu/mapping/list-of-components/EMSN024
    Description: https://data.jrc.ec.europa.eu/collection/id-0054
    Description: https://oasishub.co/dataset/surface-water-flooding-footprinthurricane-harvey-august-2017-jba
    Description: https://www.wasser.sachsen.de/hochwassergefahrenkarte-11915.html
    Keywords: ddc:551.48 ; decision support ; extreme events ; integrated flood risk management ; risk assessment
    Language: English
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  • 9
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    BODIUM—A systemic approach to model the dynamics of soil functions (2023)
    Blackwell Publishing Ltd | Oxford, UK
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    Publication Date: 2024-01-26
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The increasing demand for biomass for food, animal feed, fibre and bioenergy requires optimization of soil productivity, while at the same time, protecting other soil functions such as nutrient cycling and buffering, carbon storage, habitat for biological activity and water filter and storage. Therefore, one of the main challenges for sustainable agriculture is to produce high yields while maintaining all the other soil functions. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soils that generate those functions. We developed a soil model to simulate the impact of various agricultural management options and climate change on soil functions by integrating the relevant processes mechanistically and in a systemic way. As a special feature, we include the dynamics of soil structure induced by tillage and biological activity, which is especially relevant in arable soils. The model operates on a 1D soil profile consisting of a number of discrete layers with dynamic thickness. We demonstrate the model performance by simulating crop growth, root growth, nutrient and water uptake, nitrogen cycling, soil organic matter turnover, microbial activity, water distribution and soil structure dynamics in a long‐term field experiment including different crops and different types and levels of fertilization. The model is able to capture essential features that are measured regularly including crop yield, soil organic carbon, and soil nitrogen. In this way, the plausibility of the implemented processes and their interactions is confirmed. Furthermore, we present the results of explorative simulations comparing scenarios with and without tillage events to analyse the effect of soil structure on soil functions. Since the model is process‐based, we are confident that the model can also be used to predict quantities that have not been measured or to estimate the effect of management measures and climate states not yet been observed. The model thus has the potential to predict the site‐specific impact of management decisions on soil functions, which is of great importance for the development of a sustainable agriculture that is currently also on the agenda of the ‘Green Deal’ at the European level.〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: https://git.ufz.de/bodium/bodium_v1.0
    Keywords: ddc:631.4 ; agriculture ; computational model ; simulation ; soil microbiology ; soil structure ; sustainable soil
    Language: English
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  • 10
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    Reducing tillage intensity benefits the soil micro‐ and mesofauna in a global meta‐analysis (2022)
    Blackwell Publishing Ltd | Oxford, UK
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    Publication Date: 2024-03-22
    Description: Soil fauna drives crucial processes of energy and nutrient cycling in agricultural systems, and influences the quality of crops and pest incidence. Soil tillage is the most influential agricultural manipulation of soil structure, and has a profound influence on soil biology and its provision of ecosystem services. The objective of this study was to quantify through meta‐analyses the effects of reducing tillage intensity on density and diversity of soil micro‐ and mesofaunal communities, and how these effects vary among different pedoclimatic conditions and interact with concurrent management practices. We present the results of a global meta‐analysis of available literature data on the effects of different tillage intensities on taxonomic and functional groups of soil micro‐ and mesofauna. We collected paired observations (conventional vs. reduced forms of tillage/no‐tillage) from 133 studies across 33 countries. Our results show that reduced tillage intensity or no‐tillage increases the total density of springtails (+35%), mites (+23%), and enchytraeids (+37%) compared to more intense tillage methods. The meta‐analyses for different nematode feeding groups, life‐forms of springtails, and taxonomic mite groups showed higher densities under reduced forms of tillage compared to conventional tillage on omnivorous nematodes (+53%), epedaphic (+81%) and hemiedaphic (+84%) springtails, oribatid (+43%) and mesostigmatid (+57%) mites. Furthermore, the effects of reduced forms of tillage on soil micro‐ and mesofauna varied with depth, climate and soil texture, as well as with tillage method, tillage frequency, concurrent fertilisation, and herbicide application. Our findings suggest that reducing tillage intensity can have positive effects on the density of micro‐ and mesofaunal communities in areas subjected to long‐term intensive cultivation practices. Our results will be useful to support decision making on the management of soil faunal communities and will facilitate modelling efforts of soil biology in global agroecosystems. HIGHLIGHTS Global meta‐analysis to estimate the effect of reducing tillage intensity on micro‐ and mesofauna Reduced tillage or no‐tillage has positive effects on springtail, mite and enchytraeid density Effects vary among nematode feeding groups, springtail life forms and mite suborders Effects vary with texture, climate and depth and depend on the tillage method and frequency
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.20387/bonares-eh0f-hj28
    Keywords: ddc:631.4 ; agricultural land use ; conservation agriculture ; conventional agriculture ; soil biodiversity ; soil cultivation
    Language: English
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  • 11
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    Temperature and soil moisture change microbial allocation of pesticide‐derived carbon (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2024-03-18
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Temperature and soil moisture are known to control pesticide mineralization. Half‐life times (DT〈sub〉50〈/sub〉) derived from pesticide mineralization curves generally indicate longer residence times at low soil temperature and moisture but do not consider potential changes in the microbial allocation of pesticide‐derived carbon (C). We aimed to determine carbon use efficiency (CUE, formation of new biomass relative to total C uptake) to better understand microbial utilization of pesticide‐derived C under different environmental conditions and to support the conventional description of degradation dynamics based on mineralization. We performed a microcosm experiment at two MCPA (2‐methyl‐4‐chlorophenoxyacetic acid) concentrations (1 and 20 mg kg〈sup〉−1〈/sup〉) and defined 20°C/pF 1.8 as optimal and 10°C/pF 3.5 as limiting environmental conditions. After 4 weeks, 70% of the initially applied MCPA was mineralized under optimal conditions but MCPA mineralization reached less than 25% under limiting conditions. However, under limiting conditions, an increase in CUE was observed, indicating a shift towards anabolic utilization of MCPA‐derived C. In this case, increased C assimilation implied C storage or the formation of precursor compounds to support resistance mechanisms, rather than actual growth since we did not find an increase in the 〈italic toggle="no"〉tfdA〈/italic〉 gene relevant to MCPA degradation. We were able to confirm the assumption that under limiting conditions, C assimilation increases relative to mineralization and that C redistribution, may serve as an explanation for the difference between mineralization and MCPA dissipation‐derived degradation dynamics. In addition, by introducing CUE to the temperature‐ and moisture‐dependent degradation of pesticides, we can capture the underlying microbial constraints and adaptive mechanisms to changing environmental conditions.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Changing environmental conditions alter the MCPA degradation dynamics and the allocation of pesticide‐derived carbon to anabolic or catabolic metabolism.〈boxed-text position="anchor" content-type="graphic" id="ejss13417-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:13510754:media:ejss13417:ejss13417-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉
    Description: Collaborative Research Center 1253 CAMPOS (DFG)
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: DFG Priority Program 2322 “Soil System”
    Description: Ellrichshausen Foundation
    Description: Research Training Group “Integrated Hydrosystem modeling”
    Description: https://doi.org/10.5281/zenodo.5081655
    Keywords: ddc:631.4 ; anabolism ; carbon use efficiency ; catabolism ; effect of soil moisture and temperature ; gene‐centric process model ; MCPA biodegradation
    Language: English
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  • 12
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    Small lateral air pressure gradients generated by a large chamber system have a strong effect on CO2 transport in soil (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2024-02-09
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Gas transport in soils is usually assumed to be purely diffusive, although several studies have shown that non‐diffusive processes can significantly enhance soil gas transport. These processes include barometric air pressure changes, wind‐induced pressure pumping and static air pressure fields generated by wind interacting with obstacles. The associated pressure gradients in the soil can cause advective gas fluxes that are much larger than diffusive fluxes. However, the contributions of the respective transport processes are difficult to separate. We developed a large chamber system to simulate pressure fields and investigate their influence on soil gas transport. The chamber consists of four subspaces in which pressure is regulated by fans that blow air in or out of the chamber. With this setup, we conducted experiments with oscillating and static pressure fields. CO〈sub〉2〈/sub〉 concentrations were measured along two soil profiles beneath the chamber. We found a significant relationship between static lateral pressure gradients and the change in the CO〈sub〉2〈/sub〉 profiles (R〈sup〉2〈/sup〉 = 0.53; 〈italic toggle="no"〉p〈/italic〉‐value 〈2e‐16). Even small pressure gradients between −1 and 1 Pa relative to ambient pressure resulted in an increase or decrease in CO〈sub〉2〈/sub〉 concentrations of 8% on average in the upper soil, indicating advective flow of air in the pore space. Positive pressure gradients resulted in decreasing, negative pressure gradients in increasing CO〈sub〉2〈/sub〉 concentrations. The concentration changes were probably caused by an advective flow field in the soil beneath the chamber generated by the pressure gradients. No effect of oscillating pressure fields was observed in this study. The results indicate that static lateral pressure gradients have a substantial impact on soil gas transport and therefore are an important driver of gas exchange between soil and atmosphere. Lateral pressure gradients in a comparable range can be induced under windy conditions when wind interacts with terrain features. They can also be caused by chambers used for flux measurements at high wind speed or by fans used for head‐space mixing within the chambers, which yields biased flux estimates.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:631.4 ; advective flux ; chamber flux measurements ; static air pressure fields ; wind‐induced pressure pumping
    Language: English
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  • 13
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    Defining Hydrogeological Site Similarity with Hierarchical Agglomerative Clustering (2022)
    Blackwell Publishing Ltd | Malden, US
    Details
    Publication Date: 2024-02-28
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Hydrogeological information about an aquifer is difficult and costly to obtain, yet essential for the efficient management of groundwater resources. Transferring information from sampled sites to a specific site of interest can provide information when site‐specific data is lacking. Central to this approach is the notion of site similarity, which is necessary for determining relevant sites to include in the data transfer process. In this paper, we present a data‐driven method for defining site similarity. We apply this method to selecting groups of similar sites from which to derive prior distributions for the Bayesian estimation of hydraulic conductivity measurements at sites of interest. We conclude that there is now a unique opportunity to combine hydrogeological expertise with data‐driven methods to improve the predictive ability of stochastic hydrogeological models.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉〈italic〉Article impact statement〈/italic〉: This article introduces hierarchical clustering as a method for defining a notion of site similarity; the aim of this method is to improve the derivation of prior distributions in Bayesian methods in hydrogeology.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://github.com/GeoStat-Bayesian/geostatDB
    Description: https://github.com/GeoStat-Bayesian/exPrior
    Description: https://github.com/GeoStat-Bayesian/siteSimilarity
    Keywords: ddc:551.49 ; hydrogeological sites ; hydrogeological modeling
    Language: English
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  • 14
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    Fifty years after deep‐ploughing: Effects on yield, roots, nutrient stocks and soil structure (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2024-05-30
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Deep‐ploughing far beyond the common depth of 30 cm was used more than 50 years ago in Northern Germany with the aim to break root‐restricting layers and thereby improve access to subsoil water and nutrient resources. We hypothesized that effects of this earlier intervention on soil properties and yields prevailed after 50 years. Hence, we sampled two sandy soils and one silty soil (Cambisols and a Luvisol) of which half of the field had been deep‐ploughed 50 years ago (soils then re‐classified as Treposols). The adjacent other half was not deep‐ploughed and thus served as the control. At all the three sites, both deep‐ploughed and control parts were then conventionally managed over the last 50 years. We assessed yields during the dry year 2019 and additionally in 2020, and rooting intensity at the year of sampling (2019), as well as changes in soil structure, carbon and nutrient stocks in that year. We found that deep‐ploughing improved yields in the dry spell of 2019 at the sandy sites, which was supported by a more general pattern of higher NDVI indices in deep‐ploughed parts for the period from 2016 to 2021 across varying weather conditions. Subsoil stocks of soil organic carbon and total plant‐available phosphorus were enhanced by 21%–199% in the different sites. Root biomass in the subsoil was reduced due to deep‐ploughing at the silty site and was increased or unaffected at the sandy sites. Overall, the effects of deep‐ploughing were site‐specific, with reduced bulk density in the buried topsoil stripes in the subsoil of the sandy sites, but with elevated subsoil density in the silty site. Hence, even 50 years after deep‐ploughing, changes in soil properties are still detectable, although effect size differed among sites.〈/p〉
    Description: BonaRes http://dx.doi.org/10.13039/501100022576
    Keywords: ddc:631.4 ; aggregates ; carbon sequestration ; deep‐ploughing ; macronutrients ; subsoil ; Treposol
    Language: English
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  • 15
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    Seismic Migration. Imaging of Acoustic Energy by Wave Field Extrapolation. B. Practical Aspects (1984)
    Elsevier
    In:  Amsterdam, Elsevier, vol. 14 B, pp. 225, (ISBN 3-7643-7011-4)
    Details
    Publication Date: 1984
    Keywords: Applied geophysics ; seismic Migration ; Seismics (controlled source seismology) ; Acoustics
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    BIBLIOGRAPHY SEISMOLOGY
  • 16
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    Spectral Analysis in Geophysics (1974)
    Elsevier
    In:  Amsterdam, Elsevier, vol. 8, pp. 415, (ISBN 0-471-95596-5)
    Details
    Publication Date: 1974
    Keywords: Textbook of geophysics ; Data analysis / ~ processing ; Spectral analysis ; Spectrum ; Seismology ; Seismics (controlled source seismology) ; Bath
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  • 17
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    Fundamentals of Well-log Interpretation - 1. The Acquisition of Logging Data (1984)
    Elsevier
    In:  Amsterdam, Elsevier, vol. Developments in Petroleum Science vol. 15A, no. Publ. No. 12, pp. 9, (ISBN: 0-12-636380-3)
    Details
    Publication Date: 1984
    Keywords: Borehole geophys. ; Textbook of geophysics ; GFZ ; RUB ; GMG ; 3.45.8 ; UniL ; IfGuG ; in ; Französisch
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  • 18
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    Underground Sound: Application of Seismic Waves (1983)
    Elsevier
    In:  Amsterdam, 253 pp., Elsevier, vol. 10, no. 1, pp. 1-40, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 1983
    Keywords: Textbook of geophysics ; Acoustics ; Seismics (controlled source seismology) ; Waves ; Wave propagation
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  • 19
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    Constitution of Earth's Interior (1984)
    Elsevier
    In:  Amsterdam, Elsevier, vol. 81A and 81B, no. 22, pp. 65-70, (1405101733, 336 p.)
    Details
    Publication Date: 1984
    Keywords: Textbook of geophysics ; Earth model, also for more shallow analyses !
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    BIBLIOGRAPHY SEISMOLOGY
  • 20
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    Frequency-wavenumber analysis of Gräfenberg wide-band data (1983)
    Elsevier
    In:  Bull., Polar Proj. OP-O3A4, Signal Processing II: Theories and Applications, Bath, Elsevier, vol. 186, no. XVI:, pp. 689-692, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 1983
    Keywords: Seismology ; Seismic arrays ; Spectrum ; Broad-band ; Data analysis / ~ processing ; f-k-Analysis ; Schuessler ; Schussler
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  • 21
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    Geophysical signal analysis (1983)
    Elsevier
    In:  Bull., Polar Proj. OP-O3A4, Signal Processing II: Theories and Applications, Leiden, Elsevier, vol. 11, no. XVI:, pp. 673-680, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 1983
    Keywords: Seismology ; Seismics (controlled source seismology) ; Filter- ; Data analysis / ~ processing ; Schuessler ; Schussler
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  • 22
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    High resolution group velocity analysis (1981)
    Elsevier
    In:  Bull., Polar Proj. OP-O3A4, Computer-aided Seismic Analysis and Discrimination, London, Elsevier, vol. 16, no. 4, pp. 97-109, (ISBN 0080419208)
    Details
    Publication Date: 1981
    Keywords: Group veloc. ; Velocity analysis
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  • 23
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    Geophysical Aspects of the Energy Problem (1980)
    Elsevier
    In:  Amsterdam, I-VII + 329 pp., Elsevier, vol. 1, no. Publ. No. 12, pp. 127, (ISBN 3-540-44363-0)
    Details
    Publication Date: 1980
    Keywords: Geothermics ; application ; and ; prospection ; Earthquake hazard ; nuclear ; power ; plants ; Earthquake risk ; solar ; Energy (of earthquakes) ; pollution ; FROTH ; pp. ; 1-81, ; 279-288
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  • 24
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    Wave Propagation in Elastic Solids, 3. repr. (1980)
    Elsevier
    In:  Amsterdam, Elsevier
    Details
    Publication Date: 1980
    Keywords: Seismology ; Seismics (controlled source seismology) ; Wave propagation ; Waves ; Textbook of geophysics
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  • 25
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    Global Tectonics and Earthquake Risk (1974)
    Elsevier
    In:  Amsterdam, London, New York, xiv+320 pp., Elsevier, vol. 5, no. 22, pp. 662-664, (ISBN 1-4020-1244-6)
    Details
    Publication Date: 1974
    Keywords: Earthquake risk ; Earthquake hazard ; Earthquake engineering, engineering seismology ; Seismicity ; Plate tectonics ; Tectonics ; Seismology
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  • 26
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    Automatic on-line detection of weak earthquakes at the Gräfenberg Array (1983)
    Elsevier
    In:  Bull., Open-File Rept., Signal Processing II: Theories and Applications, Orlando, Elsevier, vol. 37, no. 16, pp. 681-684, (ISBN 1-86239-165-3, vi + 330 pp.)
    Details
    Publication Date: 1983
    Keywords: Detectors ; Seismic arrays ; Seismology ; Schuessler ; Schussler
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  • 27
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    Volcanic ash layers in deep-sea sediments and their petrological significance (1973)
    Elsevier
    In:  Earth and Planetary Science Letters, 17 (2). pp. 397-407.
    Details
    Publication Date: 2017-02-14
    Description: Volcanic ash layers, which represent the products of volcanic activity within the ocean basins, are common in sedimentary cores taken near Cobb Seamount and on the actively spreading Gorda and Juan de Fuca Ridges. Petrographic and chemical analyses of the glass shards from these deposits have revealed that they are unaltered and are as chemically representative of local volcanic events as are the glassy margins of fresh pillow basalts recovered from the same areas. The presence of unhydrated glass shards in samples as old as 3.8 my is in direct conflict with published hydration rates of both terrestrial and submarine volcanic glasses. A study of a sequence of ash layers from Cobb Seamount, which spans in time much of the Seamount's history, indicates that the volcanic products from Cobb Seamount have had alkaline affinities and that its eruptions have been becoming progressively enriched in Al2O3. Recent experimental petrological evidence and the data on the chemical compositions of Cobb Seamount and the adjacent Juan de Fuca Ridge magmas are in agreement with the hypothesis that magmas are being generated at progressively greater depths beneath Cobb Seamount as it migrates away from the Juan de Fuca Ridge.
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  • 28
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    Leg 4 of the Deep Sea Drilling Project (1971)
    American Association for the Advancement of Science (AAAS)
    In:  Science, 172 (3989). pp. 1197-1205.
    Details
    Publication Date: 2017-01-05
    Type: Article , PeerReviewed
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  • 29
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    Home occupancy by male Octopus vulgaris in a large seawater tank (1980)
    Elsevier
    In:  Animal Behaviour, 28 (4). pp. 1123-1126.
    Details
    Publication Date: 2017-02-01
    Description: Pairs of individually recognizable male Octopus vulgaris were observed in a large seawater tank containing two suitable homes (brick pots or plastic buckets). None of the animals established exclusive occupancy of one home and for much of the time both animals were associated together at the same site. Usually one of the two homes was preferred and its occupant was most likely to be the larger animal, or the earlier resident if they were of equal size. Large animals were observed to take food forcefully from smaller octopus. An arm alignment interaction is described which, it is suggested, may be a means by which two octopuses establish their relative sizes.
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  • 30
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    Sectional representations for simulating aerosol dynamics (1980)
    Elsevier
    In:  Journal of Colloid and Interface Science, 76 (2). pp. 541-556.
    Details
    Publication Date: 2016-11-30
    Description: A general method for simulating aerosol size distribution dynamics is developed. The method, based on dividing the particle size domain into sections and dealing only with one integral quantity in each section (e.g., number, surface area, or volume), has the advantages that the integral quantity is conserved within the computational domain and coagulations between all particle sizes are properly accounted for. To demonstrate the simplicity and accuracy of the method for a practical problem, the evolution of a power plant plume aerosol undergoing coagulation is simulated.
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  • 31
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    Nautilus Growth and Longevity: Evidence from Marked and Recaptured Animals (1984)
    American Association for the Advancement of Science (AAAS)
    In:  Science, 224 (4652). pp. 990-992.
    Details
    Publication Date: 2019-03-19
    Description: Study of Nautilus belauensis i its natural habitat in Palau, West Caroline Islands, shows that growth is slow (0.1 millimeter of shell per day on the average) and decreases as maturity is approached and that individuals may live at least 4 years beyond maturity. Age estimates for seven animals marked and recaptured between 45 and 355 days after release range from 14.5 to 17.2 years. These data indicate that the life-span of Nautilus may exceed 20 years and that its life strategy is very different from that of other living cephalopods.
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  • 32
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    Effect of natural concentrations on nutrient exchange between a polychaete burrow in estuarine sediment and the overlying water (1984)
    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 75 (2). pp. 171-190.
    Details
    Publication Date: 2016-04-25
    Description: The exchange of inorganic nutrients; ammonium, nitrate and reactive phosphate between burrows of the infaunal polychaete Nereis virens Sars and the overlying water was assessed using V-shaped sediment cores. Exchange was determined by monitoring ventilation current and nutrient concentration of in- and excurrent water. Ammonium supply appeared independent of overlying water concentrations, showing a constant release of 0.5 μmol·h−1 (for a 2-g individual + burrow system) at concentrations from 2 to 87 μM. Of this release ≈40% originated from worm excretion, and the rest from microbial mineralization. Nitrate and phosphate exchange appeared very sensitive to overlying water concentrations, having equilibrium (zero flux) at 10–15 and 3 μM, respectively. Below these concentrations nitrate showed a slight release (due to nitrification), whereas phosphate was released at a rate of 3.2 × 10−2 μmol·h−1 at 1 μM (mineralization and desorption). Above equilibrium they both were removed during water passage through worm burrows, reaching 0.4 μmol·h−1 for nitrate at 107 μM (nitrate reduction) and 3.7 × 10−2 μmol·h−1 for phosphate at 5.6 μM (adsorption processes). The burrow system apparently acted as a buffer for phosphate and, to some degree, nitrate in the overlying water. At the study site (Norsminde Fjord estuary) nereid burrows were estimated to increase the sediment-water interface 150%. About 17% of the water column was cycled through the sediment by Nereis each day. The worm + burrow system was estimated to release 95 μmol· m−2·h−1 ammonium to the overlying water, which was ≈76–90% of the total release of ammonium from the sediment (30–36% was worm excretion).
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  • 33
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    Calcium Carbonate Hexahydrate from Organic-Rich Sediments of the Antarctic Shelf: Precursors of Glendonites (1982)
    American Association for the Advancement of Science (AAAS)
    In:  Science, 216 (4550). pp. 1128-1131.
    Details
    Publication Date: 2018-03-08
    Description: Large euhedral crystals of calcium carbonate hexahydrate were recovered from a shelf basin of the Bransfield Strait, Antarctic Peninsula, at a water depth of 1950 meters and sub-zero bottom water temperatures. The chemistry, mineralogy, and stable isotope composition of this hydrated calcium carbonate phase, its environment of formation, and its mode of precipitation confirm the properties variously attributed to hypothetical precursors of the glendonites and thereby greatly expand their use in paleoceanographic interpretation.
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  • 34
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    Acoustic stratigraphy of the sedimentary succession west of Porcupine Bank, NE Atlantic Ocean: A preliminary account (1982)
    Elsevier
    In:  Marine Geology, 47 (1-2). pp. 17-35.
    Details
    Publication Date: 2016-04-08
    Description: Acoustic basement lies at an average of between 6.0 and 6.5 sec two-way time below sea level in the southern Rockall Trough and northern Porcupine Abyssal Plain. The overlying sedimentary succession reaches maximum thicknesses of at least 4.0 sec, and can be divided by 3 regionally-developed seismic reflecting horizons, which are used as a framework to establish an acoustic stratigraphy for the area by selecting three “type” seismic sections. These reflectors are named, in ascending order, Shackleton, Charcot and Challenger. The area is crossed by E—W basement high structures, the Clare Lineament (which may be an easterly extension of the Charlie Gibbs Fracture Zone), that separates the Porcupine Abyssal Plain from the eastern part of southern Rockall Trough. Under the latter, the post-Shackleton acoustic sequence is thickened, as if dammed to the north of the Clare Lineament, whilst a further thickening, above reflector Charcot, occurs along a NE—SW line somewhat farther north into the southern Rockall Trough. This can also be related to shallow-lying acoustic basement features. Pre-Shackleton sediments overlie a very irregular basement topography. The acoustic characters of the various sediment packages are described and it is speculated that major changes in the sedimentary environments took place across reflectors Shackleton and Challenger, the latter probably establishing the modern bottom current circulation patterns. No ages can be unequivocally assigned to the main reflectors, but previously published data suggest a late Eocene—Oligocene age for Challenger. Possible lavas or sills are identified in the succession between reflectors Shackleton and Charcot.
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  • 35
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    Late Mesozoic and Tertiary sediment supply to the eastern Cape Basin (SE Atlantic) and palaeo-drainage systems in Southwestern Africa (1984)
    Elsevier
    In:  Marine Geology, 56 (1-4). pp. 13-26.
    Details
    Publication Date: 2016-04-08
    Description: Isopach asymmetry, and sediment component changes in DSDP cores from the SE Atlantic (Orange Basin) support the hypothesis of major drainage system changes in SW Africa during late Cretaceous—Cenozoic time. This involved alternations in the use of the 28°S (modern Orange River) and 31°S (modern Olifants River) exit points across the western escarpment by rivers carrying run-off from the Upper Orange/Vaal catchment areas, as well as radical re-organizations of internal drainage geometry. It is postulated that during late Cretaceous times the 28°S exit was used, with the Middle Orange River following a course in the interior well to the south (up to 150 km) of its modern channel. Sediment discharge rates from this river were relatively high (at least 10 × 106 m3 yr−1), and resulted in rapid advancement of the continental margin sediment prism west of the mouth by large-scale slumping. The Palaeogene Orange/Vaal river exit was via the 31°S escarpment crossing, and during the later part of this period, the Cape Canyon was cut across the continental shelf and slope. A significant reduction in sediment discharge (to 2.0 × 106 m3 yr−1) suggests that the Lower Tertiary climate for SW Africa was drier than that of late Cretaceous times. However, aridity did not commence until late Miocene times, when the Orange/Vaal discharge had switched back to the 28°S exit. Modern sediment discharge rates (6.5 × 106 m3 yr−1) are relatively high and reflect soil erosion caused by agricultural activity. The two major alterations in exit point of the Orange/Vaal (late Cretaceous—early Tertiary, and late Oligocene—early Miocene) are related to periods of low sea level, which promoted river capture adjacent to the western escarpment. An additional factor in the first course change may have been the disruption of the Middle Orange channel by late Cretaceous igneous intrusions. Less important internal reorganizations of the drainage system are postulated in late Miocene—Pleistocene times. Economic implications for offshore diamond distribution are briefly mentioned.
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  • 36
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    Mesozoic palaeogeography of the Southern Cape, South Africa (1973)
    Elsevier
    In:  Palaeogeography, Palaeoclimatology, Palaeoecology, 13 (3). pp. 203-213.
    Details
    Publication Date: 2016-04-08
    Description: Four palaeogeographical reconstructions are presented for the southern Cape covering the period Late Permian to Late Cretaceous. This time spans the commencement to an advanced stage of breakup of Gondwanaland, during which the area moved from a mid-continental, high latitude, to an ocean-dominated, middle latitude position. These movements can be traced in facies changes and erosional cycles associated with the rift between West Gondwana and Antarctica (proto southwest Indian Ocean) and the later rift between South America and Africa (proto southeast Atlantic Ocean).
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  • 37
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    Post-Palaeozoic stratigraphy of the eastern Agulhas Bank, South African continental margin (1973)
    Elsevier
    In:  Marine Geology, 15 (1). pp. 1-23.
    Details
    Publication Date: 2016-04-15
    Description: The Agulhas Bank, which forms the continental margin on the southern tip of Africa, consists of a thick Meso-Cainozoic sedimentary sequence (up to 6.2 km) resting on and behind pre-Mesozoic continental acoustic basement. The stratigraphy of this sequence is outlined and its history and facies variations mentioned where they are known. Refraction seismic velocity and bottom sample data indicate a basic three-fold subdivision of the Mesozoic sequence, which can be correlated with the onshore succession in the Algoa Basin. It is separated by a major hiatus from the Cainozoic sediments, which consist of a Palaeogene and Neogene sequence subdivided by another well-defined level of erosion. Various formations within the Cainozoic are defined and named. An outline of the bathymetry of the eastern Agulhas Bank is also given.
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  • 38
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    Large allochthonous sediment masses and their role in the construction of the continental slope and rise off southwestern Africa (1980)
    Elsevier
    In:  Marine Geology, 37 (3-4). pp. 333-354.
    Details
    Publication Date: 2016-04-12
    Description: Large Neogene slumps have affected over 260,000 km2 of the outer continental margin and adjacent Cape Basin off southwestern Africa. Individual structures cover areas up to 68,700 km2 and proximally are commonly composed of huge rotated sediment blocks up to 450 m thick and several kilometers across. Seismic shocks, possibly in conjunction with lower-slope undercutting by bottom-current erosion, are suggested as possible trigger mechanisms for these features which are all thought to be post-Pliocene (possibly Pleistocene) in age. Older slumps are also recognized along the margin and four cycles of sedimentation/slumping are identified: early Upper Cretaceous (I); late Upper Cretaceous (II); Palaeogene (III); and Neogene (IV). In the main part of the Orange Basin depocentre (west of Childs Bank) the Cretaceous slump styles are thought to represent Mississippi delta-type down-slope sediment cascades (with reverse faulting and mud diapirism) over 1 km thick which resulted from very rapid dumping of terrigenous material from the Orange River. Cainozoic slumps show a different tectonic style and locus and this is thought to reflect a change in sedimentation patterns which resulted from lower terrigenous input onto the margin, higher biogenic/authigenic sedimentation, and slowed crustal subsidence. A connection possibly exists between low sea level stands and the Cainozoic episodes of slumping.
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  • 39
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    Rangia cuneata on the East Coast: Thousand Mile Range Extension, or Resurgence? (1970)
    American Association for the Advancement of Science (AAAS)
    In:  Science, 167 (3919). pp. 868-869.
    Details
    Publication Date: 2015-07-02
    Description: Rangia cuneata, a valuable clam of the estuarine zone where fluctuating salinities (from 0 to 15 parts per thousand) exclude most animals, is now developing large populations in many estuaries from Florida to Maryland. Before 1955 it was thought to be extinct on the East Coast since the Pleistocene and to be living only in Gulf Coast estuaries.
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  • 40
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    Vertical coherence of short-periodic current variations (1971)
    Elsevier
    In:  Deep Sea Research and Oceanographic Abstracts, 18 (2). pp. 179-191.
    Details
    Publication Date: 2016-09-22
    Description: A study is described which attempts to obtain information about the vertical correlation of ocean currents at frequencies higher than inertial. Current velocity and temperature data for sensor separations of 4–12 m were taken with a mooring at ‘Site D’. The coherence and phase spectra for velocity component pairs reveals that motions are rotational at low frequencies. A cut-off frequency exists above which coherence drops to low values. The limiting frequency coincides with the minimum Väisälä frequency of the total water column. These cross-spectral properties support the assumption that the motion in this frequency range is governed by internal wave dynamics. The coherence and phase spectra of temperature pairs indicate that a field of temperature structure is superimposed on the mean field which is weakly correlated to the field of motion.
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  • 41
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    The fine-structure contamination of vertical velocity spectra in the deep ocean (1974)
    Elsevier
    In:  Deep Sea Research and Oceanographic Abstracts, 21 (1). pp. 37-46.
    Details
    Publication Date: 2018-03-08
    Description: When determining vertical velocity spectra from temperature time series and the mean vertical temperature gradient, restrictions may arise friom the existence of fine-structre. Phillips (1971) and Garrett and Munk (1971_ have shown that the fine-structure contamination of internal gravity wave spectra can be written as a function of some statistical properties of the internal wave field and the vertical wave number spectrum of the fine-structure. A consistent set of current and temperature data was obtained during an experiment at Site D to study this problem. The wave number spectrum of the vertical temperature fine-structure and the apparent frequently spectrum of internal waves are determined from these data. In contrast to the asasumptions in the above models, our fine-structure data imply a wave number spectrum proportional to (wave number)−3 in the range which is important here. Using the above set of data, a model is suggested to describe the effect of fine-structure on vertical velocity spectra computed with the mean vertical temperature gradient. It indicates a maximum fine-structure contamination of the true frequency spectrum of internal gravity waves in the middle of the internal wave band, with less contamination at low and high frequencies.
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  • 42
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    The distribution of Hg, Ba, Cu and Zn in the vicinity of cupriferous sulfide deposits, Troodos complex, Cyprus (1984)
    Elsevier
    In:  Journal of Geochemical Exploration, 21 (1-3). pp. 167-174.
    Details
    Publication Date: 2016-05-30
    Description: A geochemical rock- and soil-sampling program was carried out in the vicinity of eight concealed “Cyprus type” deposits, occurring in marginal mafic to intermediate metapillow lavas of the Troodos Ophiolite Complex. The mineralization of massive and stockwork sulfide ore is characterized by the predominance of pyrite, intergrown with less chalcopyrite and minor amounts of sphalerite. Background values of Hg are in the range of 8–12 ppb for soils and 3–6 ppb for surface rocks. Anomaly/background ratios of 10:1 (soils) and 5:1 (rocks) have been found only, where Hg migrated along channels formed by faults cutting shallow-seated mineralization. Here, Hg sometimes shows significant correlations with Cu, Zn, Ba and exceptionally with Co. However in one case an Hg anomaly in soils and surface rocks was detected directly over a deposit. The use of Hg as indicator element for these types of deposits is therefore limited. Buried mineralization may be delineated more distinctly by Cu, Zn and Ba.
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  • 43
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    Natural regions of the oceans (1972)
    Elsevier
    In:  Geoforum, 3 (3). pp. 73-74.
    Details
    Publication Date: 2016-06-08
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  • 44
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    Observations of internal wave coherence in the deep ocean (1974)
    Elsevier
    In:  Deep Sea Research and Oceanographic Abstracts, 21 (8). pp. 597-610.
    Details
    Publication Date: 2016-09-22
    Description: An experiment is described which was aimed at testing assumptions and predictions of the internal wave model suggested by Garrett and Munk (1972). Two moorings were set at a depth of 2660 m with a horizontal separation of 920 m only. The results of current and temperature measurements on these moorings indicate that the field of motion is probably horizontally isotropic in the inertio-gravitational wave band. The limiting frequency for horizontal coherence is three times the frequency predicted by the theoretical model. The phase of the vertical coherence is stable over a wide frequency range and the coherence decreases towards higher frequencies. This may be due to coherent motion contaminated by uncorrelated noise at high frequencies. The results are basically in agreement with the theoretical model when taking a number of modes below 10.
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  • 45
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    Detection of Overflow Events in the Shag Rocks Passage, Scotia Ridge (1981)
    American Association for the Advancement of Science (AAAS)
    In:  Science, 213 (4512). pp. 1113-1114.
    Details
    Publication Date: 2019-01-21
    Description: During an almost yearlong period of observations made with a current meter in the fracture zone between the Falkland Islands (Islas Malvinas) and South Georgia, several overflow events were recorded at a depth of 3000 meters carrying cold bottom water from the Scotia Sea into the Argentine Basin. The outflow bursts of Scotia Sea bottom water, a mixing product of Weddell Sea and eastern Pacific bottom water, were associated with typical speeds of more than 28 centimeters per second toward the northwest and characteristic temperatures below 0.6°C. The maximum 24-hour average speed of 65 centimeters per second, together with a temperature of 0.29°C, was encountered on 14 November 1980 at a water depth of 2973 meters, 35 meters above the sea floor.
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  • 46
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    On the temperature and salinity structure of the Mediterranean water in the Northeast Atlantic (1970)
    Elsevier
    In:  Deep Sea Research and Oceanographic Abstracts, 17 (3). pp. 627-631.
    Details
    Publication Date: 2016-05-13
    Description: Typical results of continuous temperature-salinity measurements from stations west of Gibraltar are presented. Special features of the structure of the Mediterranean Water in this area in relation to the corresponding turbulent mixing and salt-fingering process are discussed: the two maxima in the vertical profiles, the variation in time of small-scale phenomena, and the step-like structure at the lower boundary of the Mediterranean Water.
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  • 47
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    Laboratory rearing of Loligo opalescens, the market squid of California (1983)
    Elsevier
    In:  Aquaculture, 33 (1). pp. 77-88.
    Details
    Publication Date: 2019-05-02
    Description: The squid Loligo opalescens (Cephalopoda, Mollusca) was reared in artificial sea water in a closed system consisting of two 1300-l circular tanks. When the squids reached mantle lengths of 20 to 30 mm, they were transferred to a 10 000-l closed system raceway. From hatching, mantle length increased exponentially at a mean rate of 1.69% per day throughout the experiment. The largest and longest-lived squid attained a maximal size of 77 mm mantle length in 8 months. Only live food organisms, which consisted of copepods, other crustaceans and fishes, were accepted by the squids. Mortality, attributed to starvation and fin damage, was greatest during the first 20 days and again between days 45 and 70.
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  • 48
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    A multivariate analysis of planktonic molluscan distribution in the Middle Atlantic Bight (1983)
    Elsevier
    In:  Continental Shelf Research, 1 (4). pp. 405-424.
    Details
    Publication Date: 2016-10-11
    Description: Faunal structure is described for the planktonic molluscs of the Middle Atlantic Bight based on two years of seasonal data from the continental shelf. Collection and taxa groups are constructed using numerical classification and reciprocal averaging ordination. Discriminant analysis is used to relate surface collection groups to physical variables, then taxa group distribution among these collection groups is analyzed by nodal fidelity analysis. The areal distribution of dominant species is presented by season, as is their surface temperature-salinity distribution. Four communities are recognized on the continental shelf. A subarctic community, including Limacina retroversa, Paedoclione doliiformis, and Clione limacina, is advected down the central shelf region from the northeast. A Gulf Stream community of weak vertical migrators, including Limacina trochiformis, Cavolinia longirostris, Creseis conica, Atlanta peroni, and A. gaudichaudi, is introduced onto the shelf in occasional intrusions across the shelf-edge front. A depth-limited warm-water community of strong vertical migrators, including Limacina inflata, L. bulimoides, L. lesueuri, and Cavolinia inflexa is generally confined offshore of the 100-m isobath since the extent of their daily vertical migration is greater than the bottom depths on the continental shelf. A coastal community, including the larvae of Loligo pealei and of Ensis directus is found in coastal water of local origin and is generally confined within a coastal boundary layer.
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  • 49
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    Glacial to interglacial changes in carbonate and clay sedimentation in the Atlantic Ocean estimated from 230Th measurements (1984)
    Elsevier
    In:  Isotope Geoscience, 46 (2). pp. 97-111.
    Details
    Publication Date: 2016-07-08
    Description: The cause of the climatically controlled fluctuations in the carbonate content of deep-sea sediments remains the subject of uncertainty and debate. Three variables are involved: supply of biogenic carbonate, loss by dissolution, and dilution by non-carbonate phases. It is suggested that 230Th, which is produced in the ocean at a constant rate provides a reliable reference for measuring variations in rate of sedimentation on a regional scale. Results of a preliminary analysis based on published data indicate that, for depths at and above the lysocline, the carbonate fluctuations observed in cores from the North Atlantic Ocean are due primarily to variations in the terrigenous clay input, which was 2–5 times higher during glacials than during interglacials. Carbonate deposition appears to have been somewhat reduced during glacials, but probably not by more than a factor of 2. From published 230Th232Th profiles it appears that the South Atlantic Ocean also received increased inputs of terrigenous clay during glacial periods.
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  • 50
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    The importance of carbonate content in the acoustic stratigraphy of Panama Basin (1984)
    Elsevier
    In:  Marine Geology, 54 (3-4). pp. 237-247.
    Details
    Publication Date: 2016-09-05
    Description: DSDP cores from areas of low (Site 505) and high heat flow (Site 504 B) near the Costa Rica Rift, together with seismic profiles from the Panama Basin, have been studied to determine the relationship between: (1) carbonate content and physical and acoustic properties; and (2) carbonate content, carbonate diagenesis and acoustic stratigraphy. Except for ash and chert layers, bulk density correlates strongly and linearly with carbonate content. Velocity is uniform downcore and only small variations at a small scale are measured. Thus an abrupt change in carbonate content will cause abrupt changes in acoustic impedance and should cause reflectors that can be detected acoustically. A comparison of seismic profiler reflection records with physical properties, carbonate content and reflection coefficients indicates that the main reflectors can be identified with ash layers, diagenetic boundaries, and carbonate content variations. Diagenesis of carbonate sediments is present at Site 504 B in a 260 m-thick ooze—chalk—limestone/chert sequence. These diagenetic sequences occur in areas of higher heat flow (200 mW m−2). Seismic profiler records can be used to map the extent and depth of these diagenetic boundaries.
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  • 51
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    Compositions of deep-sea ash layers derived from north pacific volcanic arcs: variations in time and space (1980)
    Elsevier
    In:  Journal of Volcanology and Geothermal Research, 7 (1-2). pp. 107-137.
    Details
    Publication Date: 2016-09-12
    Description: Glass separates from 115 ash layers derived from the Kamchatkan (DSDP Site 192; 34 layers), the eastern Aleutian (DSDP Site 183; 56 layers) and the Alaska Peninsula (DSDP Site 178; 25 layers) volcanic arcs have been analyzed for up to 28 elements. In addition, the abundance and diversity of associated mafic phenocrysts have been evaluated. The resulting data set has made possible an evaluation of the late Miocene to Recent changes in composition of ashes derived from North Pacific volcanic arcs and of the factors controlling the evolution of highly siliceous magmas. We find no evidence for a general transition from arc tholeiite to calc-alkalic magma parentage of ashes derived from the volcanic arcs during the last 10 m.y., but instead find 0.1- to 0.5-m.y. intervals during which particular types of volcanism are prevalent. Most convincing is the transition from arc tholeiite to calc-alkalic for ashes derived from Kamchatka during the last 0.8 m.y., a change believed to be associated with a landward shift in the site of magma generation. Considered together, ashes derived from North Pacific volcanic arcs have been becoming more siliceous during the last 1.5 m.y. and may be associated with accelerated subduction during the same time interval. Hydrous phenocrysts (e.g., biotite) are typically associated with low-silica deep-sea ashes, but not with terrestrial volcanic rocks of comparable silica contents, suggesting the important role of water in the evolution of siliceous magma. REE patterns and relative abundances of mafic phenocrysts demonstrate the importance of fractional crystallization in controlling the evolution of highly siliceous arc magmas. REE increase with increasing silica, but become less concentrated in ashes with SiO2 〉 64%. Eu anomalies increase throughout the SiO2 range. Initial fractionation is dominated by clinopyroxene and plagioclase with amphibole strongly influencing fractionation above 64% SiO2.
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  • 52
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    Incorporation of strontium into reef coral skeletal carbonate (1973)
    Elsevier
    In:  Geochimica et Cosmochimica Acta, 37 (9). pp. 2173-2190.
    Details
    Publication Date: 2019-03-07
    Description: Two thousand and twenty well-characterized coral specimens from 17 localities have been analyzed for Sr. Seventy-three genera and subgenera, mostly hermatypic scleractinians, are represented. For some genera, specimens living in surface reef environments are compared with those from 18.3 m depths on the same reefs. Growth rates for some species have also been measured at these depths at one of the sampling sites. Skeletal strontium for a given genus decreases with increasing water temperature, a relationship which previously eluded detection. Aragonite deposited by corals living on the reef at a depth of 18.3 m contains more strontium than the skeletal aragonite of the same coral genera from shallow-water, surface environments. Quantitative treatment of the data for Acropora, one of the most abundant and widely distributed of the reef-building corals, suggests that the observed strontium variations may reflect variations in the rate of skeletal calcification, rather than direct dependence upon temperature or water depth. There is evidence for ‘species effects’, apparently unrelated to growth rate differences, in that certain coral genera are consistently enriched or depleted in skeletal strontium content relative to other genera living in the same reef environments under identical ambient conditions. Temperature, salinity, water depth, seawater composition, and/or other such parameters may in part determine the levels of trace element concentration in carbonates deposited by corals and other marine invertebrates, but it would appear that these variables more directly affect physiological processes which in turn control skeletal chemistry.
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  • 53
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    Hotspot tracks and the early rifting of the Atlantic (1983)
    Elsevier
    In:  Tectonophysics, 94 (1-4). pp. 123-139.
    Details
    Publication Date: 2019-06-11
    Description: Many hotspot tracks appear to become the locus of later rifting, as though the heat of the hotspot weakens the lithosphere and tens of millions of years later the continents are split along these weakened lines. Examples are the west coast of Greenland-east coast of Labrador (Madeira hotspot), the south coast of Mexico-north coast of Honduras (Guyana hotspot), and the south coast of West Africa-north coast of Brazil (St. Helena hotspot). A modern day analog of a possible future rift is the Snake River Plain, where the North American continent is being “pre-weakened” by the Yellowstone hotspot track. This conclusion is based on reconstructions of the motions of the continents over hotspots for the past 200 million years. The relative motions of the plates are determined from magnetic anomaly isochrons in the oceans and the motion of one plate is chosen ad hoc to best fit the motions of the plates over the hotspots. However, once the motion of this one plate is chosen, the motions of all the other plates are prescribed by the relative motion constraints. In addition to the correlation between the predicted tracks and sites of later continental breakup, exposed continental shields correlate with the tracks. Their exposure may be the result of hotspot induced uplift which has led to erosion of their former platform sediment cover.
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  • 54
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    Coral Chronometers: Seasonal Growth Bands in Reef Corals (1972)
    American Association for the Advancement of Science (AAAS)
    In:  Science, 177 (4045). pp. 270-272.
    Details
    Publication Date: 2019-06-05
    Description: Autoradiagraphs and x-radiographs have been made of vertical sections through the centers of reef corals from Eniwetok. Radioactivity bands in the coral structure are caused by strontium-90 and are related to specific series of nuclear tests, thus making possible calculation of long-term growth rates. These data indicate that the cyclic variations in radial density revealed by x-radiography are annual.
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  • 55
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    Tectonic pattern of the Azores spreading centre and triple junction (1980)
    Elsevier
    In:  Earth and Planetary Science Letters, 51 (2). pp. 415-434.
    Details
    Publication Date: 2021-03-01
    Description: The major tectonic elements of the Azores triple junction have been mapped using long-range side-scan sonar. The data enable the Mid-Atlantic Ridge axis to be located with a precision of a few kilometres. Major faults and other tectonic and volcanic elements of the ridge maintain their regional trend of 010° to 020° past the triple junction area. There is no oblique spreading, and only minor transform offsets of the Mid-Atlantic Ridge occur here. The main effect of the triple junction or Azores hot spot is to diminish the amplitude of the median valley to 200 m or less. There is no axial high: a topographic high seen on several profiles is located to the east of the Mid-Atlantic Ridge spreading axis and does not appear to have any fundamental significance. The third arm of the triple junction includes the Azores srreading centre which appears to have developed as a series of en echelon rifted basins (the Terceira Rift) extending from Formigas Trough at 36.8°N, 24.5°W to a point near 39.3°N, 28.8°W. There are indications that recent activity in the spreading centre may be concentrated in a series of ridges which flank the older rifted basins. Until recently the northwest end of the Terceira Rift was connected to the Mid-Atlantic Ridge axis either directly at an RRR junction, or via a transform fault. The triple junction has probably moved south during the last 6 Ma to a positin on the Mid-Atlantic Ridge near 38.7°N. Initiation of the Azores spreading centre may have occurred during the 36 Ma B.P. rearrangement of poles, with an RFF triple junction north from the East Azores fracture zone to the North Azores fracture zone and transferring a wedge of European plate to the African plate. The tectonic elements revealed by this study are in good agreement with inferred earthquake mechanisms and with the RM2 plate tectonic model of Minster and Jordan, but east-west motion between North America and Africa does not seem to be compatible with the other motions at the triple junction unless it is of very recent (2〉3 Ma) origin.
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  • 56
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    Graben formation - the Maltese Islands - a case history (1981)
    Elsevier
    In:  Tectonophysics, 73 (1-3). pp. 151-168.
    Details
    Publication Date: 2021-06-08
    Description: The structural setting of the Maltese Islands is governed by two rift systems of different ages and trends and the interference of both. Accompanying faults are exposed at many places along cliffs and belong to the most spectacular phenomena of rift faulting of the world. Malta is part of a wide shelf bridge that connects the Ragusa platform of southern Sicily and the Tripolitanian platform of northern Libya. The archipelago is underlain by a continental crust of African provenance. The older rift generation traversing the islands strikes about 50° to 70° to create a basin-and-range structure on western Malta, Comino and eastern Gozo. This micro-province is framed by two master faults at an average distance of 14 km. Crustal extension started during the Early Miocene, as observed by growth faulting and sedimentary dikes parallel to the future rift. A syndepositional uparching of about 200 m has preceded the physiographical rifting in post-Middle Miocene times. Discrete dip-slip faulting created an external wedge block, split by internal tilt blocks of antithetic character, both compensating an average 15% crustal spreading normal to the rift axis. Shoulder upwarping of approximately 120 m has evolved synchronously with the rifting. Structures of the first generation are crosscut by still active, second-generation rift faults, which on Malta strike about 120°, but on Gozo between 80° and 90°. These faults are associated with the Pantelleria rift, whose deep trough sets immediately south of the islands. Rifting was mainly originated during Late Miocene/Early Pliocene time to continue in parts up to the Present. A set of transform faults runs through the straits on both sides of Comino to form a complicated en echelon or Riedel shear structure on easternmost Gozo and westernmost Malta. Shoulder upwarping related to the Pantelleria rift has considerably tilted the block of Malta NNE-ward and caused the inundated river valleys of the natural harbour of Valletta. The superimposition of two rift structures of different trends has been caused principally by a rotation of the controlling stress regime about 10 m.y. ago. The active Afro—Eurasian collision front is located about 200 km north and northwest of the islands. A contemporary change of plate tectonic stresses is discussed to explain the intraplate rift pattern on Malta as foreland-specific reactions to plate tectonic processes.
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  • 57
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    Tintenfische - ihre Präparation und mikroskopische Untersuchung : Innere Organisation von Männchen und Weibchen; Spermatophoren; Schale (1970)
    Elsevier
    In:  Mikrokosmos, 59 (1). pp. 171-177.
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    Publication Date: 2021-04-15
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  • 58
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    Tintenfische - ihre Präparation und mikroskopische Untersuchung : Äußerer Bau; Saugnäpfe; Radula, Auge (1970)
    Elsevier
    In:  Mikrokosmos, 59 (1). pp. 142-147.
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    Publication Date: 2021-04-15
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  • 59
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    Tintenfische - ihre Präparation und mikroskopische Untersuchung : Querschnitte verschiedener Körperregionen; Chromatophoren; Embryonalentwicklung (1970)
    Elsevier
    In:  Mikrokosmos, 59 (1). pp. 201-205.
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    Publication Date: 2021-04-15
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  • 60
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    Letter to the editors : Deep-sea cirromorphs (Cephalopoda) photographed in the Arctic Ocean (1973)
    Elsevier
    In:  Deep-Sea Research , 20 . pp. 107-108.
    Details
    Publication Date: 2020-11-16
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    Wave-formed structures and paleoenvironmental reconstruction (1984)
    Elsevier
    In:  Marine Geology, 60 (1-4). pp. 165-198.
    Details
    Publication Date: 2020-04-27
    Description: Wave-formed sedimentary structures can be powerful interpretive tools because they reflect not only the velocity and direction of the oscillatory currents, but also the length of the horizontal component of orbital motion and the presence of velocity asymmetry within the flow. Several of these aspects can be related through standard wave theories to combinations of wave dimensions and water depth that have definable natural limits. For a particular grain size, threshold of particle movement and that of conversion from a rippled to flat bed indicate flow-velocity limits. The ratio of ripple spacing to grain size provides an estimate of the length of the near-bottom orbital motion. The degree of velocity asymmetry is related to the asymmetry of the bedforms, though it presently cannot be estimated with confidence. A plot of water depth versus wave height (h—H diagram) provides a convenient approach for showing the combination of wave parameters and water depths capable of generating any particular structure in sand of a given grain size. Natural limits on wave height and inferences or assumptions regarding either water depth or wave period based on geologic evidence allow refinement of the paleoenvironmental reconstruction. The assumptions and the degree of approximation involved in the different techniques impose significant constraints. Inferences based on wave-formed structures are most reliable when they are drawn in the context of other evidence such as the association of sedimentary features or progradational sequences.
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    The ammonium content in the tissues of selected species of squid (Cephalopoda: Teuthoidea) (1983)
    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 69 . pp. 145-150.
    Details
    Publication Date: 2020-10-09
    Description: The ammonium ion (NH 4) content in the mantles, fins, arms, haemolymph, and buoyancy fluid of 17 species belonging to nine families was determined. Great individual variation of ammonium concentration was found in the buoyancy fluid of Liocranchia reinhardti (Steenstrup, 1856), i.e. 38-1108 mM, and in the vacuolized tissues of Histioteuthis macrohista N Voss, 1969, i.e. 50-775 mM.
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    New highly saturated members of the vitamin K2 series from Thermomonospora (1982)
    Elsevier
    In:  Zentralblatt für Bakteriologie Mikrobiologie und Hygiene: I. Abt. Originale C: Allgemeine, angewandte und ökologische Mikrobiologie, 3 (3). pp. 358-363.
    Details
    Publication Date: 2021-04-26
    Description: Menaquinones (vitamin K2) were the only isoprenoid quinones found in the Actinomycetes tested. Thermomonospora strains belonging to the species T. alba, T. curvata and T. fusca contained very complex mixtures of menaquinones with nine, ten and eleven isoprene units. Hexa- and octahydrogenated menaquinones with ten isoprene units constituted the major components in T. alba, whereas, octahydrogenated menaquinones with ten isoprene units predominated in T. curvata and T. fusca. Substantial amounts of hitherto undescribed hexa-, octa-, and decahydrogenated menaquinones with eleven isoprene units were also present in the three species. The representative of the taxon Thermomonospora (Actinobifida) chromogena examined differed in possessing major amounts of tetrahydrogenated menaquinones with only nine isoprene units; a pattern also found in Saccharomonospora viridis, Actinomadura flexuosa and Micromonospora halophytica subsp. halophytica. The chemotaxonomic data and supporting results of numerical taxonomic studies suggest that Actinobifida chromogena may have been wrongly classified in the genus Thermomonospora.
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    The biology of unattached seaweeds (1983)
    Elsevier
    In:  In: Progress in phycological research. Progress in phycological research, 2 . Elsevier, Amsterdam, pp. 333-386. ISBN 0-44480502-8
    Details
    Publication Date: 2018-10-12
    Type: Book chapter , NonPeerReviewed
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  • 65
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    Phosphate regeneration from sediments of the Peru continental margin by dissolution of fish debris (1981)
    Elsevier
    In:  Geochimica et Cosmochimica Acta, 45 (4). pp. 577-588.
    Details
    Publication Date: 2016-03-01
    Description: Generally, oxidative regeneration of phosphate from anoxic sediments is by microbially mediated sulfate reduction processes. Stoichiometric modelling of such reactions takes into consideration varying proportions of ‘decomposable’ organically bound P to account for the ratios among nutrients in depth-concentration profiles of near-surface sediments. New results of interstitial water composition from sediments underlying the water masses influenced by coastal upwelling of the eastern boundary current system off Peru indicate that dissolution of phosphatic fish debris represents a mechanism for remineralization of phosphate comparable to or larger in magnitude than that by oxidative regeneration of organically bound P. Dissolved interstitial phosphate from fish debris is revealed by an excess amount of phosphate over that predicted from a simple stoichiometric oxidative regeneration model and by anomalously high dissolved interstitial fluoride concentrations. Phosphate flux estimates based on diffusion from the sediment suggest that this mechanism may generate up to 10% of the nutrient pool in the waters of the Peru undercurrent. Partitioning of P among the two sources reveals further that fish debris phosphate is about four times more important than organically bound P in nutrient generation from sediments of the Peru continental margin. Not only does this mechanism of regeneration affect the nutrient cycling but may also control widespread phosphorite formation in this area.
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    Interaction of organic compounds with calcium carbonate-II. Organo-carbonate association in Recent sediments (1973)
    Elsevier
    In:  Geochimica et Cosmochimica Acta, 37 (11). pp. 2435-2447.
    Details
    Publication Date: 2016-02-29
    Description: Surface area measurements as well as organic carbon, nitrogen and phosphorus analyses on various grain size fractions of carbonate mud samples confirm that in natural environments of carbonate deposition, surface sorption processes take place which are similar to those described earlier for dissolved organics and artificially suspended calcite particles in both seawater and synthetic solutions. The specific surface area of the sediment increases from 1.8m2/g for the coarse-grained fraction to 12.5 m2/g for the fine material; likewise organic carbon, nitrogen and phosphorus increase with increasing surface area so that there are 1.20 mg C, 0.175 mg N and 0.06–0.20 mg P associated with every square meter of carbonate surface irrespective of the mineralogy of the sediment particles. It appears that the organic matter in these sediments is similar in composition, structure and quantity to the organic layers produced in sorption experiments. With their apparently defined structure and ubiquitous nature, these layers could determine the mineralogy and orientation of submarine carbonate cement or could even be a prerequisite to calcification in general.
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    The Ultrastructure of Skeletogenesis in Hermatypic Corals (1980)
    Elsevier
    In:  International Review of Cytology, 67 . pp. 171-214.
    Details
    Publication Date: 2018-10-29
    Description: This chapter discusses coral skeletogenesis, focusing on the morphology of the skeletogenic tissues. It reviews the light and electron microscope studies carried out in this regard, illustrating the example of the morphology of the skeletogenic tissues of the coral Pocillopora damicornis. A structural organic matrix is present in the adult skeleton of Pocillopora damicornis. One component of this structural matrix is present transiently at the growth surface of the skeleton. It consists of individual sheaths enveloping each forming aragonite crystal. These crystal sheaths, plus some small extracellular vesicles that are presumed to represent a precursor for the sheaths, are together implicated in the hypotheses for coral calcification. The hypotheses fall into the following three broad categories: (1) algal removal of possible inhibitory substances; (2) a general stimulatory effect of algal metabolism; and (3) algal contribution to a skeletal organic matrix.
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  • 68
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    Patterns of groundwater salinity changes in a deep continental-oceanic transect off the southeastern Atlantic coast of the U.S.A. (1981)
    Elsevier
    In:  Journal of Hydrology, 54 (1-3). pp. 95-105.
    Details
    Publication Date: 2018-07-25
    Description: Investigations of formation-fluid salinities in a transect from western Georgia to the edge of the Blake Plateau off the coast of Georgia show surprisingly similar hydrochemical features offshore and onshore. A fresh-brackish wedge of groundwater (〈25 g/kg total dissolved solids) lies beneath the shelf to a depth of ∼ 900 m. On land, brackish waters extend to a maximum depth of ∼ 1.2 km below sea level in Lowndes County, Georgia. In deeper horizons, hypersaline brines (〉 100 g/kg) occur in Lower Cretaceous (?) strata. These strata have a pronounced evaporitic (anhydritic) character in the offshore segment. Strong salinity gradients in interstitial waters signify buried evaporite deposits at drill sites beneath the Blake Plateau.
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  • 69
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    Ventilation rate and arousal in the octopus (1983)
    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 69 . pp. 129-136.
    Details
    Publication Date: 2021-01-19
    Description: Observations on undisturbed, individually isolated, Octopus vulgaris show that ventilation rate is strongly related to "arousal" or activation. Ventilation rate may be recorded visually by a screened observer or remotely, using carbon electrodes connected to a pen recorder via an impedance coupler to register the associated water movements in a small experimental chamber. The method allows a quantifiable behavioural characteristic to be measured objectively. It has been used to demonstrate that O. vulgaris responds to certain chemical stimuli in flowing sea water with a sharply increased ventilation rate. This result is taken to show distance chemoreception in this cephalopod.
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    How can biogeomechanical alterations in shales impact caprock integrity and CO2 storage? (2021)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: Highlights • Coupled geomicrobiology and geomechanics to investigate alterations in shales. • Microbial process can alter the mechanics, mineralogy, and microstructure of shales. • Biogeomechanical alterations reduced permeability by 93% and porosity by 38%. • Microfractures in shales can be sealed during biogeomechanical alterations. • Biogeomechanical alterations can enhance CO2 storage security and caprock integrity. Shales have been a major focus of the energy industry over the past few decades. Recently, there is a paradigm shift in the energy industry to low-carbon solutions, such as carbon capture and storage (CCS), to mitigate global warming caused by carbon footprint. The problem of long-term safe and efficient geological CO2 storage (GCS) and caprock integrity are some of the major challenges impeding large-scale CCS application. Here, we investigated how localized and bulk biogeomechanical alterations could potentially impact caprock integrity and CO2 storage in depleted shale reservoirs. We cultivated the shale core samples (containing both artificial-induced and pre-existing natural fractures) with a cultured microbial solution at specific temperature, time, and growth conditions. Subsequently, we obtain the properties of the fractured shale rock samples impacted by this microbial process. We investigate the impact of the mechanical responses due to the microbial process, on the long-term integrity and storage potentials of CO2 in shale reservoirs. Our results suggest that in Eagle Ford, Marcellus, and Niobrara shale formations, microbially-altered local and bulk mechanical properties can enhance the long-term caprock integrity and CO2 storage security by: (1.) Increasing the localized (+19% unconfined compressive strength, −20% Poisson’s ratio, +35% fracture toughness) and bulk (+50% unconfined compressive strength, −13% Poisson’s ratio) mechanical integrity; (2.) Decreasing permeability (−93%) and porosity (−38%); (3.) Altering the clay mineral content (−56%), calcite content (+21%), and morphology; (4.) Occluding microfractures; and (5.) Mitigating any potential leakage to the atmosphere through the caprock. This study considers the heterogeneity of shales, and provide valuable insights and viable assessment in solving the long-term GCS application in depleted hydrocarbon reservoirs.
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    Release kinetics as a key linkage between the occurrence of flame retardants in microplastics and their risk to the environment and ecosystem: A critical review (2020)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: Highlights • Internal diffusion often controls the releases of flame retardants from microplastics. • Fick's law can describe the releases of additive flame retardants from microplastics. • Effects of temperature, plastic matrix, and particle size can be predicted by models. • Weathering of plastic matrix can greatly accelerate the releases of flame retardants. • Low fluxes of flame retardants released from microplastics pose no risk to ecosystem. The widely occurring debris of plastic materials, particularly microplastics, can be an important source of flame retardants, which are one of the main groups of chemicals added in the production of plastics from polymers. This review provides an overview on the use of flame retardants in plastic manufacturing, the kinetics of their releases from microplastics, the factors affecting their releases, and the potential environmental and ecosystem risk of the released flame retardants. The releases of flame retardants from microplastics typically involve three major steps: internal diffusion, mass transfer across the plastic-medium boundary layer, and diffusion in the environmental medium, while the overall mass transfer rate is commonly controlled by diffusion within the plastic matrix. The overall release rates of additive flame retardants from microplastics, which are dependent on the particle's geometry, can often be described by the Fick's Law. The physicochemical properties of flame retardant and plastic matrix, and ambient temperature all affect the release rate, which can be predicted with empirical and semi-empirical models. Weathering of microplastics, which reduces their particle sizes and likely disrupts their polymeric structures, can greatly accelerate the releases of flame retardants. Flame retardants could also be released directly from the microplastics ingested by aquatic organisms and seabirds, with physical and chemical digestion in the bodies significantly enhancing their release rates. Limited by the extremely slow diffusion in plastic matrices, the fluxes of flame retardants released from microplastics are very low, and are unlikely to pose significant risk to the ecosystem in general. More research is needed to characterize the mechanical, chemical, and biological processes that degrade microplastics and accelerate the releases of flame retardants and to model their release kinetics from microplastics, while efforts should also be made to develop environmentally benign flame retardants to ultimately minimize their risk to the environment and ecosystem.
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    Microplastic-associated pathogens and antimicrobial resistance in environment (2022)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: The ubiquitous use of microplastics and their release into the environment especially the water bodies by anthropogenic/industrial activities are the major resources for microplastic contamination. The widespread and often injudicious use of antimicrobial drugs or antibiotics in various sectors including human health and hygiene, agriculture, animal husbandry and food industries are leading to the release of antibiotics into the wastewater/sewage and other water bodies, particularly in urban setups and thus leads to the antimicrobial resistance (AMR) in the microbes. Microplastics are emerging as the hubs as well as effective carriers of these microbial pathogens beside their AMR-genes (ARGs) in marine, freshwater, sewage/wastewater, and urban river ecosystems. These drug resistant bacteria interact with microplastics forming synthetic plastispheres, the ideal niche for biofilm formations which in turn facilitates the transfer of ARGs via horizontal gene transfer and further escalates the occurrence and levels of AMR. Microplastic-associated AMR is an emerging threat for human health and healthcare besides being a challenge for the research community for effective management/address of this menace. In this review, we encompass the increasing prevalence of microplastics in environment, emphasizing mainly on water environments, how they act as centers and vectors of microbial pathogens with their associated bacterial assemblage compositions and ultimately lead to AMR. It further discusses the mechanistic insights on how microplastics act as hosts of biofilms (creating the plastisphere). We have also presented the modern toolbox used for microplastic-biofilm analyses. A review on potential strategies for addressing microplastic-associated AMR is given with recent success stories, challenges and future prospects.
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    Metabolomic profile and discrimination of white quinoa seeds from Peru based on UHPLC-HRMS and multivariate analysis (2021)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: In the present work, an untargeted metabolomic approach based on ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC–HRMS) was performed for the discrimination of 25 accessions of white quinoa from main production zones of Peru. From the fingerprint analysis, a total of eighty-four metabolites were tentatively identified based on their accurate mass measurements and MS/MS data. Among them, forty-six compounds are reported here for the first time in C. quinoa (eight phenolics, one ecdysteroid, and thirty-seven saponins), twenty-four of them would correspond to new structures. Principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA) were used to analyze the metabolomic data. As a result, the samples were distributed into two groups. The compounds contributing to the differences between these groups were identified by S-plot analysis.
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    UAV-based thermal imaging and heat output estimation of a coastal geothermal resource: La Jolla beach, Baja California, Mexico (2021)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: Highlights • UAV-based thermal imaging allows precise mapping of diffusive thermal water discharge. • High tidal ranges affect fluid flow and promote larger thermal anomaly. • The La Jolla thermal anomaly is caused by a discharge of 330 ± 44 L s−1 of thermal water. • The La Jolla advective heat output (40.5 ± 5.2 MWt) can power a desalinization plant. The exploration of unexploited geothermal resources is required to encourage the use of renewable energy. This study focuses on La Jolla beach, Ensenada, Mexico. The beach hosts a thermal anomaly with temperatures of up to 52 °C at the surface and up to 93 °C at 20 cm depth. The objectives were to: map the thermal anomaly, understand the impact of tides, quantify the thermal water discharge rate and heat output, and discuss a direct use of the energy. The mapping was performed with Unmanned Aerial Vehicles equipped with optical and thermal cameras at two different dates. Additional temperature measurements were performed with a thermocouple, while the total fluid discharge was estimated from flow measurements. A comparison between the campaigns indicated that the highest surface temperature area was more than three times larger in 2019 than in 2018 (259 m2 vs. 69 m2). Such change was due to the tidal range and associated hydrostatic pressure variations. The total thermal water discharge is 330 ± 44 L s−1, which corresponds to an advective heat output of 40.5 ± 5.2 MWt. The use of this energy in a Multi-Effect Distillation desalinization plant can contribute to cover the shortage of freshwater in Ensenada.
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    An informed thought experiment exploring the potential for a paradigm shift in aquatic food production (2021)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: The Neolithic Revolution began approximately 10,000 years ago and is characterized by the ultimate, nearly complete transition from hunting and gathering to agricultural food production on land. The Neolithic Revolution is thought to have been catalyzed by a combination of local population pressure, cultural diffusion, property rights and climate change. We undertake a thought experiment that examines trends in these key hypothesized catalysts of the Neolithic Revolution and patterns of today to explore whether society could be on a path towards another paradigm shift in food production: away from hunting of wild fish towards a transition to mostly fish farming. We find similar environmental and cultural pressures have driven the rapid rise of aquaculture, during a period that has now been coined the Blue Revolution, providing impetus for such a transition in coming decades to centuries (as opposed to millennia). However, we also highlight the interacting and often mutually reinforcing impacts of 1) technological and scientific advancements, 2) environmental awareness and collective action and 3) globalization and trade influencing the trajectory and momentum of the Blue Revolution from patterns and processes of the Neolithic Revolution. We present two qualitative narratives that broadly fall within two future trajectories of seafood production: 1) a ubiquitous aquaculture transition and 2) commercial aquaculture and fisheries coexistence. Each narrative contains two sub-narratives based on differing management and regulatory strategies for aquaculture and fisheries. This scenarios approach aims to encourage logical, forward thinking, and innovative solutions to complex systems’ dynamics. Scenario-based thought experiments are useful to explore large scale questions, increase the accessibility to a wider readership, and ideally catalyze discussion around proactive governance mechanisms. We argue the future is not fixed and society now has greater foresight and capacity to choose the workable balance between fisheries and aquaculture that supports economic, environmental, cultural and social objectives through combined planning, policies, and management.
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    Procure, Bank, Release: Carbon Removal Certificate Reserves to Manage Carbon Prices on the Path to Net-Zero (2022)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: The European Union cap-and-trade emissions trading system (EU ETS) faces two challenges in the context of the European Green Deal. First, to meet the Paris temperature target, emissions in the energy and industrial sectors must fall to net-zero and then even become net-negative. Second, there is a concern that excessive CO2 price spikes and volatility on this path will jeopardize the political acceptance and support for emissions trading as a climate policy instrument. Conditional supply of carbon removal credits (CRCs) to support dynamic carbon price caps would make it possible to stabilize the market in the transition from positive to net-negative emissions trading while keeping the net-emissions path unchanged. CRCs would be assigned for carbon removal achieved for example with methods like Direct Air Carbon Capture and Storage or Bioenergy with Carbon Capture and Storage and would be used by companies under the EU ETS to compensate for their emissions. However, we suggest that there would be no direct exchange between emitting companies under the EU ETS and carbon removal companies, i.e., the demand and supply side of CRCs, during an initial phase. Instead, we suggest assigning an institutional mandate to for example a carbon central bank (CCB) to organize the supply of CRCs. Under this mandate, carbon removal would be procured, would be translated into a corresponding number of CRCs, and a fraction of it could be auctioned to the market at a later point in time, provided that market prices exceed a certain (dynamic) price cap.
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    Structures and functions of algal glycans shape their capacity to sequester carbon in the ocean (2022)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: Algae synthesise structurally complex glycans to build a protective barrier, the extracellular matrix. One function of matrix glycans is to slow down microorganisms that try to enzymatically enter living algae and degrade and convert their organic carbon back to carbon dioxide. We propose that matrix glycans lock up carbon in the ocean by controlling degradation of organic carbon by bacteria and other microbes not only while algae are alive, but also after death. Data revised in this review shows accumulation of algal glycans in the ocean underscoring the challenge bacteria and other microbes face to breach the glycan barrier with carbohydrate active enzymes. Briefly we also update on methods required to certify the uncertain magnitude and unknown molecular causes of glycan-controlled carbon sequestration in a changing ocean.
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    The effects of atmospheric and lateral buoyancy fluxes on Labrador Sea mixed layer depth (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: The depth of the Labrador Sea mixed layer during winter convection is a balance between atmospheric buoyancy loss and lateral buoyancy exchange, and is notoriously difficult to represent accurately in ocean and climate models. This study shows that lateral exchanges of heat and salt between the shelf and the interior are smaller in a regional coupled ocean–sea ice model at higher vertical resolution (75 levels compared with 50 levels), due in part to altered bathymetry along the Greenland shelf. Reduced lateral exchange results in a stronger stratification in the interior of the Labrador Sea, with stronger convection resistance which results in unrealistically shallow mixed layers. The westward fluxes of heat and salt associated with Irminger Water at Cape Farewell are 50 % and 33 % lower, respectively, with higher vertical resolution. Exchanges south of the Labrador Sea from the North Atlantic Current are also smaller, contributing to a reduction in salt and heat import into the Labrador Sea interior. When the high resolution model is forced with a stronger wintertime buoyancy loss at the ocean surface, this weakens the Labrador Sea stratification, allowing the forcing to break through the freshwater cap and increasing convection, bringing mixed layer depths back to observed values. A strong atmospheric forcing can therefore compensate for a reduction in lateral advection. The mixed layer depths, which are representative of convection and Labrador Sea water formation, will be the focus in this study. Therefore, this study suggests that convection and Labrador Sea Water formation is a complex interplay of surface and lateral fluxes, linked to stratification thresholds.
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    Atmospheric Dynamics in High Obliquity Planets (2020)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Ongoing discoveries of terrestrial exoplanets and the desire to determine their habitability have created an increasing demand for studies of a wide range of climatic regimes and atmospheric circulations. These studies have, in turn, challenged our understanding of our own planet’s atmospheric dynamics and provided new frameworks with which we can further our understanding of planetary atmospheres. In this work, we use an idealized moist general circulation model in aquaplanet configuration to study the atmospheric circulation of terrestrial planets with high obliquities. With seasonally varying insolation forcing and a shallow slab ocean as a lower boundary, we emphasize seasonal phenomena that might not be captured in simulations with annual mean forcing and that might involve nonlinear behaviors. By progressively increasing obliquity, we explore the response of the large-scale atmospheric circulation to more extreme seasonal cycles and a reversed annual mean equator-to-pole insolation distribution, and its impact on the energy and water cycles. We show that for high obliquities, the large-scale atmospheric circulation and the meridional energy transport are dominated by seasonally reversing broad cross-equatorial Hadley cells that transport energy from the summer to the winter hemisphere and significantly mitigate temperature extremes. These overturning cells also play a major role in shaping the planet’s hydrological cycle, with the associated ascending branches and precipitation convergence zones becoming progressively broader and more poleward shifted into the summer hemisphere with higher obliquities. While not embedded within the Hadley cell ascending branches, the hot summer poles of high obliquity planets experience nonnegligible precipitation during and at the end of the warm season: during the summer, lower-level moist static energy maxima at the summer poles force locally enhanced convective activity. As temperatures rapidly drop at the end of the summer and convective activity decreases, the water-holding capacity of the atmosphere decreases and water vapor stored in the atmospheric column rapidly condenses out, extending the duration of the summer pole rainy season into the corresponding autumn. Our study reveals novel understanding of how atmospheric dynamics might influence a planet’s overall climate and its variability.
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    Large scale upper-level precursors for dust storm formation over North Africa and poleward transport to the Iberian Peninsula. Part I: An observational analysis (2020)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: The analysis of three extreme African dust outbreaks over the Iberian Peninsula (IP) shows that a double Rossby wave breaking (RWB) process in the polar jet (PJ) creates the conditions for dust storm formation over subtropical deserts in North Africa and the restructuring of upper-level air flows critical for the dust transport poleward after ablation. Two consecutive anticyclonic RWBs initiate over the IP and the adjacent Atlantic, the first commencing 10 days before dust reaches the IP and the second three to five days later. The first RWB becomes quasi-stationary over the eastern Mediterranean when the second RWB develops. In turn, the first RWB blocks downstream propagation of the second, which is amplified by energy reflection poleward from the first break causing vortex intensification and equatorward propagation over the Atlas as well as a strengthening and coupling of the subtropical jet (STJ) to circulations in the ITCZ. Zonal flows are blocked and sustained low-level northeasterlies/easterlies are induced across northwest Africa. The three events present substantial differences in the location and geometry of key upper- and low-level subsynoptic features that organize the dust storms over the Sahara following the second break. Dust lifted by either the cold outflow from convective downdrafts or by orographic gravity waves interacts with terrain-induced and larger scale circulations and is transported to the IP. The location of the cyclonic large scale signal from the second RWB to the west or over the Atlas and the blocking of zonal flows are key for the poleward dust transport.
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    Biogeomechanical alteration of near-wellbore properties: Implications for hydrocarbon recovery (2021)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: Highlights • Coupled microbiology and geomechanics to investigate alterations in shales. • Microbial process can alter the near-wellbore of shale gas reservoirs. • Microbial alterations of near-wellbore rock properties can weaken mechanical integrity. • Biogeomechanical alterations increased porosity (+42%) & permeability (+6430%). • Biogeomechanical alteration with other stimulation methods can improve gas recovery. Shale gas reservoirs, with typically ultra-low permeabilities, have been a major focus of hydrocarbon production over the past few decades. In this paper, we investigated how biogeomechanical alteration of near-wellbore properties could potentially impact hydrocarbon recovery from low-permeability reservoirs, using Wolfcamp shale and Niobrara shale formations. We first obtained the geomechanical properties using the scratch test method, in addition to the mineralogical, microstructural, and porosity and permeability measurements of the shale gas samples. Subsequently, we treated the core samples with a cultured microbial solution at distinct conditions. Further, we obtained the corresponding new geomechanical properties, in addition to the new mineralogical, microstructural, and porosity measurements of the samples impacted by the process. Finally, we showed the implications of the altered near-wellbore properties for hydrocarbon recovery from shale gas reservoirs. Our results suggest that in shale gas reservoirs, microbial-induced alterations of near well-bore properties could temporally reduce its mechanical integrity (Wolfcamp shale = −21% unconfined compressive strength, −42% scratch toughness; Niobrara shale = −24% unconfined compressive strength, −14% scratch toughness), increase porosity (+43%) and permeability (+6430%), and impact the microstructural and mineralogical properties. The near-wellbore biogeomechanical alterations could potentially improve hydrocarbon recovery by enhancing: (1.) the susceptibility for induced fractures to nucleate and propagate during reservoir-stimulation; (2.) flow pathways to improve hydrocarbon recovery.
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    Development of a drone-borne volcanic plume sampler (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Both chemical and isotopic compositions of volcanic plumes are highly useful in evaluating the present status of active volcanoes. Monitoring their temporal changes can facilitate the forecasts of volcanic activity as well. In the present study, we developed a drone-borne automatic sampler for volcanic plumes in which an output signal from a sulfur dioxide (SO2) sensor triggered a pump to collect samples when its SO2 concentration exceeded a predefined threshold. First, we tested the automatic sampler while holding the device by hand at Iwo-yama volcano, Kirishima volcanic complex, Japan, where the fumaroles were accessible. Second, we fitted the sampler on a drone at Nakadake central cone, Aso volcano, Japan, where only the crater rim was accessible. In both sampling campaigns, good consistency in isotope ratios (2H/1H) of molecular hydrogen (H2) between samples collected by the automatic sampler and those collected directly into pre-evacuated flasks was obtained. Furthermore, by using the drone-borne sampler at Aso volcano, we obtained plume samples with higher concentrations of H2 and carbon dioxide than those taken directly into flasks at the crater rim. Our sampler can be utilized to collect volcanic plume samples for the determination of stable isotopic compositions in general by subsequent laboratory analysis and the remote establishment of fumarole outlet temperature based on the 2H/1H ratios of hydrogen, including their temporal changes.
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    Constructing vertical measurement logs using UAV-based photogrammetry: Applications for multiscale high-resolution analysis of coarse-grained volcaniclastic stratigraphy (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Volcaniclastic stratigraphy can be difficult to map and describe due to its complex nature. However, such stratigraphy preserves information about fluctuations in volcanic activity and sedimentation and is vital to understanding volcanic systems. Uncrewed aerial vehicle (UAV) based analysis of volcanic stratigraphy can enhance mapping and analysis, especially on vertical surfaces where outcrop exposure is greatest. Here we present a method for using small UAVs to produce vertical grain size and bedding measurement logs, or quantitative stratigraphic columns, of vertical volcaniclastic stratigraphy. We demonstrate the range of high-accuracy measurements and parameters that can be collected for building measurement logs using consumer grade UAVs through a case study in the Marysvale volcanic field where we collected 34,422 grain measurements from 21 individual units. The purpose of producing such measurement logs is to enhance lithofacies analysis through the use of large quantitative datasets and improve the reproducibility of data reporting. Whereas descriptions of volcaniclastic units such as those describing grading are often reported qualitatively, we describe methods for calculating numerical parameters for enhanced lithologic analysis including grain size, grading, clast to matrix ratios, and shape characteristics. The methods described in this paper can enhance field data acquisition, mapping, and quantitative analysis of volcaniclastic deposits and are applicable to a wide range of other geologic settings where coarse-grained clastic sedimentary deposits exist.
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    Inferring parental areas of juvenile mussels using hydrodynamic modelling (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Mussel aquaculture is heavily reliant on wild mussel populations that supply juveniles (spat) for seeding farms. However, little is often known about parent populations, representing a risk for the sustainability of the industry. We used hydrodynamic back-tracking models to identify potential parental areas that provision green-lipped mussel (Perna canaliculus) spat across a range of settlement sites in New Zealand's largest aquaculture area. Median parental area varied considerably between 19 km2 for sites located in enclosed bays and a maximum of 〉1150 km2 for sites located in open bays. Median distance to parent populations ranged between 1.8 and 21.4 km, with a maximum larval dispersal estimated to be ca. 100 km. Small seasonal variations in parental area and dispersal distance were detected in some regions, whereas inter-annual variability was relatively minor. Regional connectivity between settlement and parental regions ranged between a minimum of 45% of larvae originating in the same parental region, to maximum retention rates of 99.9% for sites in enclosed bays, implying a considerable regional variation in the potential for self-seeding and exporting mussel larvae other areas. Our results also delineate areas that support spatfall by identifying likely locations for wild or farmed parental populations, and by establishing the spatial extent where mussel reproduction and larval development through to settlement take place. These dispersal and connectivity patterns are crucial to support management decisions for the conservation and restoration of parental populations, and other environmental constraints, such as water quality, which are necessary to ensure the sustainability of spat catching operations that enable shellfish farming.
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    Equilibrium mono- and multicomponent adsorption models: From homogeneous ideal to heterogeneous non-ideal binding (2020)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Aqueous sorption processes play an important role in, for example, pollutant binding to natural nanoparticles, colloid stability, separation and enrichment of components and remediation processes. In this article, which is a tribute to Hans Lyklema, models of localized (ad)sorption of molecules and ions from aqueous solution on homogeneous and heterogeneous nanoparticles are presented. The discussed models range from ideal monocomponent sorption on homogeneous (Langmuir) and heterogeneous sites, to multicomponent ideal sorption on homogeneous and heterogeneous sites, multicomponent multisite ion complexation with charge distribution (CD-MUSIC) and non-ideal competitive adsorption on heterogeneous sites (NICA). Attention is also paid to lateral interaction, site-induced aggregation, binding stoichiometry and multilayer formation. Electrical double layer models are discussed in relation to ion binding on impermeable and permeable nanoparticles. Insight in models that can describe sorption of molecules and ions on nanoparticles leads to awareness of the limitations of using simple models for complex systems and is needed for the selection and application of an appropriate model for a given system. This is relevant for all practical sorption processes and for a better understanding of the role of natural nanoparticles in the binding of nutrients and pollutants.
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    Corals evolve in an unusual way (2020)
    Elsevier
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    Publication Date: 2023-01-04
    Description: These are the first animals to pass mutations found outside sex cells
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    The effect of off-bottom versus on-bottom oyster culture on total and pathogenic Vibrio spp. abundances in oyster tissue, water and sediment samples (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Varying culture methods are commonly used for eastern oyster, Crassostrea virginica, aquaculture in the Northeast United States. Vibrio vulnificus and V. parahaemolyticus, two human pathogenic bacteria species, accumulate in this edible, filter feeding shellfish. This study examined the use of two methods in an intertidal area (oysters cultured in trays and in bags on sediment) and two methods in a subtidal area (oysters cultured in trays and loose on the sediment) in Massachusetts over the growing season in 2015. Abundance of total V. vulnificus along with total and pathogenic (tdh+/trh+) V. parahaemolyticus were determined in oysters, sediment and water using real-time PCR. Temperature, salinity, turbidity and chlorophyll were continually measured every 15 min at each location. There were significantly higher abundances of total and pathogenic V. parahaemolyticus in on-bottom cultured oysters, while significantly higher abundances of V. vulnificus were identified in oysters from off-bottom culture in a subtidal location in Duxbury Bay, MA. In an intertidal location, Wellfleet Bay, MA, significantly higher abundances of total and tdh+ V. parahaemolyticus were found in off-bottom oysters, but significantly higher abundances of V. vulnificus and trh+ V. parahaemolyticus were found in on-bottom oysters. Spearman's correlation indicated that temperature is positively associated with concentrations of Vibrio spp. in oysters, water and sediment, but positive correlations between salinity and Vibrio spp. was also observed. Conversely, turbidity had a negative effect on Vibrio spp. concentrations in all sample types. There was no observed relationship inferred between chlorophyll and Vibrio spp. abundances in oysters, water or sediment.
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    Resolution of the atmospheric model matters for the Northern Hemisphere Mid-Holocene climate (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Highlights: • Temperature anomalies for the Mid-Holocene compared to preindustrial are significantly different in the low- and high-resolution versions of the atmospheric model ECHAM5 • For summer, shortwave cloud radiative forcing emerges as an important factor. • For boreal winter, differences are mainly related to circulation changes. • Anomaly differences are regionally as large as the mid-Holocene minus preindustrial temperature signals. Abstract: This study evaluates the dependence of simulated surface air temperatures on model resolution and orography for the mid-Holocene. Sensitivity experiments with the atmospheric general circulation model ECHAM5 are performed with low (∼3.75°, 19 vertical levels) and high (∼1.1°, 31 vertical levels) resolution. Results are compared to the respective preindustrial runs. It is found that the large-scale temperature anomalies for the mid-Holocene (compared to preindustrial) are significantly different in the low- and high-resolution versions. For boreal winter, differences are mainly related to circulation changes caused by the response to thermal forcing in conjunction with orographic resolution. For summer, shortwave cloud radiative forcing emerges as an important factor. The anomaly differences (low minus high resolution version) in the Northern Hemisphere are regionally as large as the anomalous mid-Holocene temperature signals. Furthermore, they depend on the applied surface boundary conditions. We conclude that the resolution matters for the Northern Hemisphere response in mid-Holocene simulations, which should be taken into account in model-model and data-model comparisons.
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    Pseudoalteromonas piscicida X-8 causes bleaching disease in farmed Saccharina japonica (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Saccharina japonica is a commercially farmed seaweed of global importance. However, disease occurrence during different stages of cultivation can result in substantial economic losses. Identification of the causative agents of disease remains a significant bottleneck to the large scale cultivation of S. japonica. In this study, an aerobic heterotrophic, flagellated, rod-shaped Gram-negative bacterial strain X-8 was isolated from the bleaching diseased S. japonica sporelings. Pathogenecity of strain X-8 was tested by re-infection assay. The ultrastructural changes of infected S. japonica cells by strain X-8 indicated that chloroplasts were the first organelle responding to X-8 infection with deformed structure and later followed by fragmented nucleus. However, the ultra-structure of mitochondria and cell wall remained intact during the re-infection. Based on 16S rRNA gene sequence, morphological and biochemical characteristics, strain X-8 was designated as Pseudoalteromonas piscicida X-8. The pathogenicity of P. piscicida X-8 was identified by Koch's Postulate under laboratory conditions. Our results will not only help to establish a stable experimental model between the pathogenic bacteria and the host S. japonica to further elucidate the virulence mechanisms, but will also provide information for disease management to effectively prevent and mitigate the occurrence of bleaching disease of S. japonica at nursery stage.
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    Influence of successive landslides on topographic changes revealed by multitemporal high-resolution UAS-based DEM (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Highlights • UAV surveys can be used for evaluating long-term hillslope morphology evolution. • Successive landslides influence frequency distributions of topographic features. • Successive landslides gradually reduce slope gradient, roughness and local relief. • The slope gradient changes with elevation. Landslides are recognized as dominant geomorphic events of morphological evolution in most mountainous and hilly landscapes. However, the lack of multitemporal high-resolution topographic data has resulted in a lack of quantitative estimates of topographic changes influenced by successive landslides. Taking a typical hillslope with successive loess landslides in the Heifangtai loess tableland, China, as an example, we conducted four unmanned aerial system (UAS) surveys and created corresponding high-resolution digital elevation models (HRDEMs) and orthophotos. We found that multitemporal UAS surveys have become a powerful new approach for addressing local topographic changes and evolution over a relatively long time series. Moreover, landslides can leave persistent geomorphic imprints on hillslope topography. The frequency distributions of topographic indexes are significantly influenced by successive landslides. The mean slope gradient, roughness and local relief decreased with successive landslide occurrences, whereas the mean topographic wetness index (TWI) increased. However, the mean slope aspect was almost unchanged by successive landslides. Furthermore, analysis of the coefficient of variation demonstrates that the frequency distribution of the slope gradient becomes more dispersed with landslide occurrences, while the slope aspect and TWI become more concentrated. The slope gradient changes with elevation. More broadly, this study provides new insights into the prediction of the local topographic feature changes and morphology evolution trends caused by successive landslides.
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    Shale softening degree and rate induced by fracturing fluid under THMC coupling condition (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Highlights • Shale samples were exposed to slick water under the condition of 120 °C and 20 MPa within 30–90 days. • Microindentation was conducted to probe the distance-dependent, gradient alteration to shale mechanical properties. • The average rate of softening advancement was estimated as 0.13 mm/day. • The dissolution of carbonate minerals, pyrite oxidation and clay mineral osmotic swelling determine the shale softening. The shale softening behavior caused by hydrofracturing fluid is of great influence for the fracture conductivity and ultimate recovery of oil and gas from reservoir formations. This paper presents an experimental study on the characterization of a shale after being softened by the coupled thermo-hydro-mechanical-chemical (THMC) treatments that simulate the high-temperature and high-pressure rock-fluid interactions occurring in deep reservoirs during and after hydraulic fracturing. Microindentation tests were conducted to characterize the degradation degree and rate of mechanical properties of THMC-treated samples, and X-ray diffraction (XRD), scanning electron microscope (SEM), and micro-computed tomography (micro-CT) were carried out to analyze compositional and microstructural alterations of samples prior to and after THMC treatment. The results show that Young's modulus, hardness, and fracture toughness degrade significantly upon THMC treatment, and the average softening rate was estimated as 0.13 mm/day. The degradation of mechanical properties of the softened zones is primarily owing to the porous microstructure and crack propagation, resulting from the dissolution of carbonates, pyrite oxidation and the clay mineral osmotic swelling. These findings can provide a good insight of shale-fracturing fluid interactions, phenomenological behavior of shale softening that take place in deep reservoirs at elevated temperatures and pressures, and shed lights on the design, and operation of shale gas exploration.
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    Low-cost UAV applications in dynamic tropical volcanic landforms (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: The recent and growing development and availability of unmanned aerial vehicles/systems (UAV, UAS, or “drones”) in volcanology has promoted a significant advance in volcanic surveillance of active volcanoes and in the characterization of volcanic landforms and hazards. However, in the tropics with heavy rainfall, deep volcanic soils and high relief, UAV surveying for volcanic geomorphology and volcanic hazards seems to be a relatively unexplored technique. Our aim is to present and promote innovative low-cost (〈$3000) UAV applications in volcanology to reduce costs and improve high-resolution quality (up to 8 cm/pixel) data acquisition in highly dynamic landscapes. Our results contribute to the state of the art of UAV applications in volcanic landforms in tropical developing countries where nearly half of the globally active volcanoes are located. Our findings prove that UAV's are a low-cost technique that can map large extensions of geomorphological features with accessibility limitations due to geological hazards and/or private property restrictions in short time. We surveyed four active volcanic sites in Costa Rica, Central America to illustrate potential applications of UAV mapping and geomorphological analysis of lava flows, debris avalanches, lahar deposits (debris flows) and biogeomorphic landscape changes due to forest succession. Analysis derived from the digital imagery captured by the UAV allowed to determine accurate volume calculations, surface roughness characteristics, morphometric quantifications, supervised surface classifications, and in combination with hydraulic modelling to assess hazards in urban planning. We discuss the utility, limitations, and future directions of low-cost UAV surveying in the geomorphological and geological analysis of tropical volcanic landforms and processes.
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    The use of UAV remote sensing for observing lava dome emplacement and areas of potential lahar hazards: An example from the 2017–2019 eruption crisis at Mount Agung in Bali (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Mount Agung (the highest volcano in Bali, Indonesia) began to erupt on November 21, 2017, after having been dormant for 53 years. More than 100,000 people were evacuated within the hazard zone between September 2017 (when the highest volcanic alert was issued) and early 2018. The eruptions continued until June 2019, accompanied by at least 110 explosions. During the eruptive crisis, the observation of the lava dome's emplacement was essential for mitigating the potential hazard. Details of the lava dome growth, including the volumetric changes and effusion rates, provide valuable information about potential eruption scenarios and lahar depositions. In this paper, the essential role of multi-temporal unmanned aerial vehicle (UAV) images in the monitoring of Mt. Agung's lava dome, and in determining the areas of potential lahar hazards during the crisis between 2017 and 2019 is described. A fixed-wing UAV was launched outside the hazard zone to photograph the lava dome on five occasions. Image enhancement, machine learning, and photogrammetry were combined to improve image quality, remove point clouds outliers, and generate digital terrain models (DTMs) and orthoimages. The analysis of the obtained DTMs and orthoimages resulted in qualitative and quantitative data highlighting the changes inside the crater and on the surrounding slopes. These results reveal that, from November 25 to December 16, 2017, the lava dome grew vertically by 126 m and reached a volume of 26.86 ± 0.64 × 106 m3. In addition, its surface experienced a maximal uplift of approximately 52 m until July 2019 with the emergence of a new dome with a volume estimated at 9.52 ± 0.086 × 106 m3. The difference between the DTMs of 2017 and 2019 reveals the total volume of erupted material (886,100 ± 8000 m3) that was deposited on the surrounding slopes. According to the lahar inundation simulation, the deposited material may cause dangerous lahars in 21 drainages, which extend in the north (N), north-east (N-E), south (S), south-east (S-E), and south-west (S-W) sectors of the volcano. This paper presents the use of UAV remote sensing for the production of high-spatial resolution DTMs, which can be used to both observe the emplacement of a lava dome, and to identify areas with potential lahar risk during a volcano crisis.
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    Mapping and classification of volcanic deposits using multi-sensor unoccupied aerial systems (2021)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Highlights • A new approach using UAS to map and classify volcanic deposits is described. • Tephra and lava are distinguished by their roughness and solar heating rate. • Solar heating rate decreases as lava transitions from pāhoehoe to ʻaʻā. • We compare manual and machine learning classification methods. The deposits from volcanic eruptions represent the record of activity at a volcano. Identification, classification, and interpretation of these deposits are crucial to the understanding of volcanic processes and assessing hazards. However, deposits often cover large areas and can be difficult or dangerous to access, making field mapping hazardous and time-consuming. Remote sensing techniques are often used to map and identify the deposits of volcanic eruptions, though these techniques present their own trade-offs in terms of image resolution, wavelength, and observation frequency. Here, we present a new approach for mapping and classifying volcanic deposits using a multi-sensor unoccupied aerial system (UAS) and demonstrate its application on lava and tephra deposits associated with the 2018 eruption of Sierra Negra volcano (Galápagos Archipelago, Ecuador). We surveyed the study area and collected visible and thermal infrared (TIR) images. We used structure-from-motion photogrammetry to create a digital elevation model (DEM) from the visual images and calculated the solar heating rate of the surface from temperature maps based on the TIR images. We find that the solar heating rate is highest for tephra deposits and lowest for ʻaʻā lava, with pāhoehoe lava having intermediate values. This is consistent with the solar heating rate correlating to the density and particle size of the surface. The solar heating rate for the lava flow also decreases with increasing distance from the vent, consistent with an increase in density as the lava degasses. We combined the surface roughness (calculated from the DEM) and the solar heating rate of the surface to remotely classify tephra deposits and different lava morphologies. We applied both supervised and unsupervised machine learning algorithms. A supervised classification method can replicate the manual classification while the unsupervised method can identify major surface units with no ground truth information. These methods allow for remote mapping and classification at high spatial resolution (〈 1 m) of a variety of volcanic deposits, with potential for application to deposits from other processes (e.g., fluvial, glacial) and deposits on other planetary bodies.
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    Working during non-standard work time undermines intrinsic motivation (2022)
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    Publication Date: 2023-01-04
    Description: How do people’s perceptions about when they work affect their intrinsic motivation? We find that working during non-standard work time (weekends/holidays) versus standard work time (Monday-Friday, 9-to-5) undermines people’s intrinsic motivation for their professional and academic pursuits. Working during non-standard work time decreases intrinsic motivation by causing people to consider better uses of their time. That is, people generate more upward counterfactual thoughts, which mediates the effect of work time on reduced intrinsic motivation. As a causal test of this process, increasing consideration of upward counterfactuals during standard work time reduces intrinsic motivation, whereas decreasing consideration of upward counterfactuals during non-standard work time helps employees and students maintain intrinsic motivation for their professional and academic pursuits. Overall, we identify a novel determinant of intrinsic motivation and address a real challenge many people face: How changing work schedules affect interest and enjoyment of work, with important consequences for work outcomes.
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    Seagrasses and local environment control the bacterial community structure and carbon substrate utilization in brackish sediments (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Seagrasses are complex benthic coastal ecosystems that play a crucial role in organic matter cycling and carbon sequestration. However, little is known about how seagrasses influence the structure and carbon utilization potential of benthic bacterial communities. This study examined the bacterial communities in monospecific and mixed meadows of seagrasses and compared with bulk (unvegetated) sediments from Chilika, a brackish water coastal lagoon of India. High-throughput sequencing of 16S rRNA genes revealed a vegetation effect in terms of differences in benthic bacterial community diversity, composition, and abundances in comparison with bulk sediments. Desulfobacterales, Chromatiales, Enterobacteriales, Clostridiales, Vibrionales, and Acidimicrobiales were major taxa that contributed to differences between seagrass and bulk sediments. Seagrasses supported ∼5.94 fold higher bacterial abundances than the bulk due to rich organic carbon stock in their sediments. Co-occurrence network demonstrated much stronger potential interactions and connectedness in seagrass bacterial communities compared to bulk. Chromatiales and Acidimicrobiales were identified as the top two keystone taxa in seagrass bacterial communities, whereas, Dehalococcoidales and Rhizobiales were in bulk communities. Seagrasses and local environmental factors, namely, water depth, water pH, sediment salinity, redox potential, total organic carbon, available nitrogen, sediment texture, sediment pH, and sediment core depth were the major drivers of benthic bacterial community composition. Carbon metabolic profiling revealed that heterotrophic bacteria in seagrass sediments were much more metabolically diverse and active than bulk. The utilization of carbon substrate guilds, namely, amino acids, amines, carboxylic acids, carbohydrates, polymers, and phenolic compounds was enhanced in seagrass sediments. Metabolic mapping predicted higher prevalence of sulfate-reducer and N2 fixation metabolic functions in seagrass sediments. Overall, this study showed that seagrasses control benthic bacterial community composition and diversity, enhance heterotrophic carbon substrate utilization, and play crucial roles in organic matter cycling including degradation of hydrocarbon and xenobiotics in coastal sediments.
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    HRM and 16S rRNA gene sequencing reveal the cultivable microbiota of the European sea bass during ice storage (2020)
    Elsevier
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    Publication Date: 2023-01-04
    Description: The total cultivable microbiota of the ice-stored European sea bass (Dicentrarchus labrax), the most important commercial fish species of the Mediterranean aquaculture, was determined using 16S rRNA gene sequence analysis. High Resolution Melting (HRM) curve profiles and sequencing analysis (V3–V4 region of the 16S rRNA gene) were used respectively for the differentiation and identification of the collected isolates from six time intervals (day 0, 4, 8, 12, 14 and 16) while fish were stored in ice. HRM analysis differentiated the unknown microbiota in ten groups (208 isolates) and in two single isolates based on their HRM curve profiles. The isolates with HRM profiles which were 〉91% similar within each group were found to belong to the same species using sequencing analysis. Thus, the ten groups consist of representatives of Psychrobacter glacincola, Ps. alimentarius, Ps. cryohalolentis, Ps. maritimus, Ps. fozii, Pseudomonas sp., Paeniglutamicibacter sp., Carnobacterium sp., Leucobacter aridicolis and Bacillus thuringiensis. Based on this approach, Ps. cryohalolentis was found to be the most dominant phylotype at the beginning of fish shelf-life compared to other species. The abundance of this bacterium decreased throughout storage, while Ps. glacincola increased and dominated at the time of the sensory minimum acceptability (day 14) and rejection (day 16). To conclude, HRM could be used for the rapid determination of sea bass microbiota, using the representatives of each group as reference bacterial strains, in order for scientists to solve rapidly stakeholders problems related with microbial quality or safety of fish.
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    Relationships between gene transcription and contaminant concentrations in Baltic ringed seals: a comparison between tissue matrices (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Ringed seals (Pusa hispida) are slowly recovering in the eastern and northern parts of the Baltic Sea after years of hunting pressure and contaminant exposure. Still, consequences of anthropogenic activities such as contaminant exposure and increasing temperatures are stressors that continue to have deleterious effects on their habitat and health. Transcription profiles of seven health-related genes involved in xenobiotic metabolism, endocrine disruption and stress were evaluated in blood, blubber, and liver of Baltic ringed seals in a multi-tissue approach. Selected persistent organic pollutants and total mercury concentrations were measured in blubber and liver, and muscle and liver of these animals, respectively. Concentrations of contaminants varied across tissues on a lipid weight basis but not with sex. mRNA transcript levels for all seven target genes did not vary between sexes or age classes. Transcript levels of thyroid hormone receptor alpha (TRα), retinoic acid receptor alpha (RARα) and heat shock protein 70 (HSP70) correlated with levels of persistent organic pollutants. TRα transcript levels also correlated positively with mercury concentrations in the liver. Of the three tissues assessed in this multi-tissue approach, blubber showed highest transcription levels of aryl hydrocarbon receptor nuclear translocator (ARNT), thyroid stimulating hormone receptor beta (TSHβ), oestrogen receptor alpha (ESR1) and peroxisome proliferator activated receptor alpha (PPARα). The wide range of genes expressed highlights the value of minimally invasive sampling (e.g. biopsies) for assessing health endpoints in free-ranging marine wildlife and the importance of identifying optimal matrices for targeted gene expression studies. This gene transcript profile study has provided baseline information on transcript levels of biomarkers for early on-set health effects in ringed seals and will be a useful guide to assess the impacts of environmental change in Baltic pinnipeds for conservation and management.
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    Fair train-test split in machine learning: Mitigating spatial autocorrelation for improved prediction accuracy (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Highlights • Our data split method handles spatial autocorrelation and imposes prediction fairness. • The sets impose fair algorithms with similar difficulty in all machine learning steps. • Kriging variance is a surrogate of spatial prediction difficulty. • The resulting training and test sets are compatible with any machine learning model. Machine learning supports prediction and inference in multivariate and complex datasets where observations are spatially related to one another. Frequently, these datasets depict spatial autocorrelation that violates the assumption of identically and independently distributed data. Overlooking this correlation result in over-optimistic models that fail to account for the geographical configuration of data. Furthermore, although different data split methods account for spatial autocorrelation, these methods are inflexible, and the parameter training and hyperparameter tuning of the machine learning model is set with a different prediction difficulty than the planned real-world use of the model. In other words, it is an unfair training-testing process. We present a novel method that considers spatial autocorrelation and planned real-world use of the spatial prediction model to design a fair train-test split. Demonstrations include two examples of the planned real-world use of the model using a realistic multivariate synthetic dataset and the analysis of 148 wells from an undisclosed Equinor play. First, the workflow applies the semivariogram model of the target to compute the simple kriging variance as a proxy of spatial estimation difficulty based on the spatial data configuration. Second, the workflow employs a modified rejection sampling to generate a test set with similar prediction difficulty as the planned real-world use of the model. Third, we compare 100 test sets' realizations to the model's planned real-world use, using probability distributions and two divergence metrics: the Jensen-Shannon distance and the mean squared error. The analysis ranks the spatial fair train-test split method as the only one to replicate the difficulty (i.e., kriging variance) compared to the validation set approach and spatial cross-validation. Moreover, the proposed method outperforms the validation set approach, yielding a minor mean percentage error when predicting a target feature in an undisclosed Equinor play using a random forest model. The resulting outputs are training and test sets ready for model fit and assessment with any machine learning algorithm. Thus, the proposed workflow offers spatial aware sets ready for predictive machine learning problems with similar estimation difficulty as the planned real-world use of the model and compatible with any spatial data analysis task.
    Type: Article , PeerReviewed
    Format: text
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    Visioning a framework for effective environmental management of deep-sea polymetallic nodule mining: Drivers, barriers, and enablers (2022)
    Elsevier
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    Publication Date: 2023-01-04
    Description: Deep-sea polymetallic nodule mining is expected to start within the next decade. There is currently a pressing need to develop best practices to minimise the potential environmental impacts of this new industry. Project-specific environmental management processes, such as environmental impact assessment (EIA), and the associated environmental management and monitoring plan (EMMP), must be effective to sufficiently mitigate environmental impacts of deep-sea mining (DSM) projects. This paper identifies the key drivers, barriers, and enablers to polymetallic nodule mining from a review of recent literature and develops an environmental management framework prior to any exploitation licenses being approved. We explore how the drivers to polymetallic nodule mining are framed in a global context, including claims that it will facilitate clean energy transitions, increase mineral supply diversity, and improve life cycle sustainability. We highlight the key barriers to effective environmental management, including epistemic uncertainty about deep-sea ecosystems, assessment of harmful effects from mining activities, and stakeholder support for a social license. We identify three enablers, including the precautionary approach, the ecosystem approach, and adaptive management, all of which are highly interdependent and must be operationalised to address the identified barriers. The results of this analysis indicate a complex social-ecological narrative infused throughout recent literature, emphasising the need for systems-level thinking and broader stakeholder participation. We present an environmental management framework designed to support good industry practice and guide future research.
    Type: Article , PeerReviewed
    Format: text
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