ALBERT

Description: The paper describes the architecture for a data repository and distribution system to be used in the case of a SETI detection event. This system is conceptually modelled after the Deep Space Network, although the hardware and infrastructure involved are different and substantially less expensive to operate. The system is designed to accommodate a large number of users from a variety of fields who wish to contribute to the analysis and comprehension effort that would follow the detection of an information-bearing signal.

Description: Under the potential to reconstruct the past climatic and atmospheric conditions from a deep ice core in the coastal Antarctic site (Styx Glacier), an 8.84 m long firn core (73°50.975′ S, 163°41.640′ E; 1623 m a.s.l.) was initially studied to propose a reliable age scale for the local estimation of snow accumulation rate. The seasonal variations of δ18O, methanesulfonic acid (MSA) and non-sea-salt sulfate (nssSO42–) were used for the firn core dating and revealed 25 annual peaks (from 1990 to 2014) with volcanic sulfate signal. The observed declining trend in annual accumulation rate with a mean value of 146 ± 60 kg m–2 a–1 is likely to be linked to the changes of sea-ice extent in the Ross Sea region. Moreover, the temporal variation of the annual mean δ18O, an annual flux of MSA and nssSO42– also likely to be under the influence of ice-covered and open water area. This study suggests a potential to recover past changes in an oceanic environment and will be useful for the interpretation of the long ice core drilled at the same site.

Description: The evaluation of potential landslides in mountain areas is a very complex process. Currently, event understanding is scarce due to information limitations. Identifying the whole chain of events is not a straightforward task, and the impacts of mass-wasting processes depend on the conditions downstream of the origin. In this paper, we present an example that illustrates the complexities in the evaluation of the chain of events that may lead to a natural disaster. On 16 December 2017, a landslide occurred in the Yelcho mountain range (southern Chile). In that event, 7 million m3 of rocks and soil fell on the Yelcho glacier, depositing 2 million m3 on the glacier terminal, and the rest continued downstream, triggering a mudflow that hit Villa Santa Lucía in Chilean Patagonia and killing 22 people. The complex event was anticipated in the region by the National Geological and Mining Survey (Sernageomin in Spanish). However, the effects of the terrain characteristics along the run-out area were more significant than anticipated. In this work, we evaluate the conditions that enabled the mudflow that hit Villa Santa Lucía. We used the information generated by Sernageomin's professionals after the mudflow. We carried out geotechnical tests to characterize the soil. We simulated the mudflow using two hydrodynamic programs (r.avaflow and Flo-2D) that can handle the rheology of the water–soil mixture. Our results indicate that the soil is classified as volcanic pumices. This type of soil can be susceptible to the collapse of the structure when subjected to shearing (molding), flowing as a viscous liquid. From the numerical modeling, we concluded that r.avaflow performs better than Flo-2D. The mudflow was satisfactorily simulated using a water content in the mixture ranging from 30 % to 40 %, which would have required a source of about 3 million m3 of water. Coupling the simulations and the soil tests that we performed, we estimated that in the area scoured by the mudflow, there were probably around 2 800 000 m3 of water within the soil. Therefore, the conditions of the valley were crucial to enhancing the impacts of the landslide. This result is relevant because it highlights the importance of evaluating the complete chain of events to map hazards. We suggest that in future hazard mapping, geotechnical studies in combination with hydrodynamic simulation should be included, in particular when human lives are at risk.

Description: Connections between vegetation and soil thermal dynamics are critical for estimating the vulnerability of permafrost to thaw with continued climate warming and vegetation changes. The interplay of complex biophysical processes results in a highly heterogeneous soil temperature distribution on small spatial scales. Moreover, the link between topsoil temperature and active layer thickness remains poorly constrained. Sixty-eight temperature loggers were installed at 1–3 cm depth to record the distribution of topsoil temperatures at the Trail Valley Creek study site in the northwestern Canadian Arctic. The measurements were distributed across six different vegetation types characteristic for this landscape. Two years of topsoil temperature data were analysed statistically to identify temporal and spatial characteristics and their relationship to vegetation, snow cover, and active layer thickness. The mean annual topsoil temperature varied between −3.7 and 0.1 ∘C within 0.5 km2. The observed variation can, to a large degree, be explained by variation in snow cover. Differences in snow depth are strongly related with vegetation type and show complex associations with late-summer thaw depth. While cold winter soil temperature is associated with deep active layers in the following summer for lichen and dwarf shrub tundra, we observed the opposite beneath tall shrubs and tussocks. In contrast to winter observations, summer topsoil temperature is similar below all vegetation types with an average summer topsoil temperature difference of less than 1 ∘C. Moreover, there is no significant relationship between summer soil temperature or cumulative positive degree days and active layer thickness. Altogether, our results demonstrate the high spatial variability of topsoil temperature and active layer thickness even within specific vegetation types. Given that vegetation type defines the direction of the relationship between topsoil temperature and active layer thickness in winter and summer, estimates of permafrost vulnerability based on remote sensing or model results will need to incorporate complex local feedback mechanisms of vegetation change and permafrost thaw.

Description: Clouds play an important role in the Arctic surface radiative budget, impacting the seasonal evolution of Arctic sea-ice cover. We explore the large-scale impacts of springtime and early summer (March through July) cloud and radiative fluxes on sea ice by comparing these fluxes to seasonal ice volume losses over the central Arctic basin, calculated for available observational years 2004–2007 (ICESat) and 2011–2017 (CryoSat-2). We also supplement observation data with sea-ice volume computed from the Pan-Arctic Ice–Ocean Modeling and Assimilation System (PIOMAS) during summer months. We find that the volume of sea ice lost over the melt season is most closely related to observed downwelling longwave radiation in March and early summer (June and July) longwave cloud radiative forcing, which together explain a large fraction of interannual variability in seasonal sea-ice volume loss (R2 = 0.71, p = 0.007). We show that downwelling longwave fluxes likely impact the timing of melt onset near the sea-ice edge, and can limit the magnitude of ice thickening from March to April. Radiative fluxes in June and July are likely critical to seasonal volume loss because modeled data show the greatest ice volume reductions occur during these months.

Description: Evapotranspiration (ET) from tropical forests serves as a critical moisture source for regional and global climate cycles. However, the magnitude, seasonality, and interannual variability of ET in the Congo Basin remain poorly constrained due to a scarcity of direct observations, despite the Congo being the second-largest river basin in the world and containing a vast region of tropical forest. In this study, we applied a water balance model to an array of remotely sensed and in situ datasets to produce monthly, basin-wide ET estimates spanning April 2002 to November 2016. Data sources include water storage changes estimated from the Gravity Recovery and Climate Experiment (GRACE) satellites, in situ measurements of river discharge, and precipitation from several remotely sensed and gauge-based sources. An optimal precipitation dataset was determined as a weighted average of interpolated data by Nicholson et al. (2018), Climate Hazards InfraRed Precipitation with Station data version 2 (CHIRPS2) , and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks–Climate Data Record product (PERSIANN-CDR), with the relative weights based on the error magnitudes of each dataset as determined by triple collocation. The resulting water-balance-derived ET (ETwb) features a long-term average that is consistent with previous studies (117.2±3.5 cm yr−1) but displays greater seasonal and interannual variability than seven global ET products. The seasonal cycle of ETwb generally tracks that of precipitation over the basin, with the exception that ETwb is greater in March–April–May (MAM) than in the relatively wetter September–October–November (SON) periods. This pattern appears to be driven by seasonal variations in the diffuse photosynthetically active radiation (PAR) fraction, net radiation (Rn), and soil water availability. From 2002 to 2016, Rn, PAR, and vapor-pressure deficit (VPD) all increased significantly within the Congo Basin; however, no corresponding trend occurred in ETwb. We hypothesize that the stability of ETwb over the study period despite sunnier and less humid conditions may be due to increasing atmospheric CO2 concentrations that offset the impacts of rising VPD and irradiance on stomatal water use efficiency (WUE).

Description: Optimum management of irrigated crops in regions with shallow saline groundwater requires a careful balance between application of irrigation water and upward movement of salinity from the groundwater. Few field-validated surrogate models are available to aid in the management of irrigation water under shallow groundwater conditions. The objective of this research is to develop a model that can aid in the management using a minimum of input data that are field validated. In this paper a 2-year field experiment was carried out in the Hetao irrigation district in Inner Mongolia, China, and a physically based integrated surrogate model for arid irrigated areas with shallow groundwater was developed and validated with the collected field data. The integrated model that links crop growth with available water and salinity in the vadose zone is called Evaluation of the Performance of Irrigated Crops and Soils (EPICS). EPICS recognizes that field capacity is reached when the matric potential is equal to the height above the groundwater table and thus not by a limiting hydraulic conductivity. In the field experiment, soil moisture contents and soil salt conductivity at five depths in the top 100 cm, groundwater depth, crop height, and leaf area index were measured in 2017 and 2018. The field results were used for calibration and validation of EPICS. Simulated and observed data fitted generally well during both calibration and validation. The EPICS model that can predict crop growth, soil water, groundwater depth, and soil salinity can aid in optimizing water management in irrigation districts with shallow aquifers.

Description: In this paper, we quantify the CO2 and N2O emissions from denitrification over the Amazonian wetlands. The study concerns the entire Amazonian wetland ecosystem with a specific focus on three floodplain (FP) locations: the Branco FP, the Madeira FP and the FP alongside the Amazon River. We adapted a simple denitrification model to the case of tropical wetlands and forced it by open water surface extent products from the Soil Moisture and Ocean Salinity (SMOS) satellite. A priori model parameters were provided by in situ observations and gauging stations from the HYBAM Observatory. Our results show that the denitrification and the trace gas emissions present a strong cyclic pattern linked to the inundation processes that can be divided into three distinct phases: activation, stabilization and deactivation. We quantify the average yearly denitrification and associated emissions of CO2 and N2O over the entire watershed at 17.8 kgN ha−1 yr−1, 0.37 gC-CO2 m−2 yr−1 and 0.18 gN-N2O m−2 yr−1 respectively for the period 2011–2015. When compared to local observations, it was found that the CO2 emissions accounted for 0.01 % of the integrated ecosystem, which emphasizes the fact that minor changes to the land cover may induce strong impacts on the Amazonian carbon budget. Our results are consistent with the state of the art of global nitrogen models with a positive bias of 28 %. When compared to other wetlands in different pedoclimatic environments we found that the Amazonian wetlands have similar emissions of N2O with the Congo tropical wetlands and lower emissions than the temperate and tropical anthropogenic wetlands of the Garonne (France), the Rhine (Europe) and south-eastern Asia rice paddies. In summary our paper shows that a data-model-based approach can be successfully applied to quantify N2O and CO2 fluxes associated with denitrification over the Amazon basin. In the future, the use of higher-resolution remote sensing products from sensor fusion or new sensors like the Surface Water and Ocean Topography (SWOT) mission will permit the transposition of the approach to other large-scale watersheds in tropical environments.

Description: In the framework of the EU Copernicus programme, the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the Joint Research Centre (JRC) is forecasting daily fire weather indices using its medium-range ensemble prediction system. The use of weather forecasts in place of local observations can extend early warnings by up to 1–2 weeks, allowing for greater proactive coordination of resource-sharing and mobilization within and across countries. Using 1 year of pre-operational service in 2017 and the Fire Weather Index (FWI), here we assess the capability of the system globally and analyse in detail three major events in Chile, Portugal and California. The analysis shows that the skill provided by the ensemble forecast system extends to more than 10 d when compared to the use of mean climate, making a case for extending the forecast range to the sub-seasonal to seasonal timescale. However, accurate FWI prediction does not translate into accuracy in the forecast of fire activity globally. Indeed, when all fires detected in 2017 are considered, including agricultural- and human-induced burning, high FWI values only occur in 50 % of the cases and are limited to the Boreal regions. Nevertheless for very large events which were driven by weather conditions, FWI forecasts provide advance warning that could be instrumental in setting up management and containment strategies.

Description: The impact of a hexamethyldisiloxane (HMDSO) treatment on the response of doped SnO2 sensors is investigated for acetone, carbon monoxide and hydrogen. The sensor was operated in temperature cycles based on the DSR concept (differential surface reduction). According to this concept, the rate constants for the reduction and oxidation of the surface after fast temperature changes can be evaluated and used for quantification of reducing gases as well as quantification and compensation of sensor poisoning by siloxanes, which is shown in this work. Increasing HMDSO exposure reduces the rate constants and therefore the sensitivity of the sensor more and more for all processes. On the other hand, while the rate constants for acetone and carbon monoxide are reduced nearly to zero already for short treatments, the hydrogen sensitivity remains fairly stable, which greatly increases the selectivity. During repeated HMDSO treatment the quasistatic sensitivity, i.e. equilibrium sensitivity at one point during the temperature cycle, rises at first for all gases but then drops rapidly for acetone and carbon monoxide, which can also be explained by reduced rate constants for oxygen chemisorption on the sensor surface when considering the generation of surface charge.

Description: Anaerobic nitrate-dependent Fe(II) oxidation (NDFeO) is widespread in various aquatic environments and plays a major role in iron and nitrogen redox dynamics. However, evidence for truly enzymatic, autotrophic NDFeO remains limited, with alternative explanations involving the coupling of heterotrophic denitrification with the abiotic oxidation of structurally bound or aqueous Fe(II) by reactive intermediate nitrogen (N) species (chemodenitrification). The extent to which chemodenitrification is caused (or enhanced) by ex vivo surface catalytic effects has not been directly tested to date. To determine whether the presence of either an Fe(II)-bearing mineral or dead biomass (DB) catalyses chemodenitrification, two different sets of anoxic batch experiments were conducted: 2 mM Fe(II) was added to a low-phosphate medium, resulting in the precipitation of vivianite (Fe3(PO4)2), to which 2 mM nitrite (NO2-) was later added, with or without an autoclaved cell suspension (∼1.96×108 cells mL−1) of Shewanella oneidensis MR-1. Concentrations of nitrite (NO2-), nitrous oxide (N2O), and iron (Fe2+, Fetot) were monitored over time in both set-ups to assess the impact of Fe(II) minerals and/or DB as catalysts of chemodenitrification. In addition, the natural-abundance isotope ratios of NO2- and N2O (δ15N and δ18O) were analysed to constrain the associated isotope effects. Up to 90 % of the Fe(II) was oxidized in the presence of DB, whereas only ∼65 % of the Fe(II) was oxidized under mineral-only conditions, suggesting an overall lower reactivity of the mineral-only set-up. Similarly, the average NO2- reduction rate in the mineral-only experiments (0.004±0.003 mmol L−1 d−1) was much lower than in the experiments with both mineral and DB (0.053±0.013 mmol L−1 d−1), as was N2O production (204.02±60.29 nmol L−1 d−1). The N2O yield per mole NO2- reduced was higher in the mineral-only set-ups (4 %) than in the experiments with DB (1 %), suggesting the catalysis-dependent differential formation of NO. N-NO2- isotope ratio measurements indicated a clear difference between both experimental conditions: in contrast to the marked 15N isotope enrichment during active NO2- reduction (15εNO2=+10.3 ‰) observed in the presence of DB, NO2- loss in the mineral-only experiments exhibited only a small N isotope effect (

Description: Temperature appears to be the best predictor of species composition of planktonic foraminifera communities, making it possible to use their fossil assemblages to reconstruct sea surface temperature (SST) variation in the past. However, the role of other environmental factors potentially modulating the spatial and vertical distribution of planktonic foraminifera species is poorly understood. This is especially relevant for environmental factors affecting the subsurface habitat. If such factors play a role, changes in the abundance of subsurface-dwelling species may not solely reflect SST variation. In order to constrain the effect of subsurface parameters on species composition, we here characterize the vertical distribution of living planktonic foraminifera community across an east–west transect through the subtropical South Atlantic Ocean, where SST variability was small, but the subsurface water mass structure changed dramatically. Four planktonic foraminifera communities could be identified across the top 700 m of the transect. Gyre and Agulhas Leakage surface faunas were predominantly composed of Globigerinoides ruber, Globigerinoides tenellus, Trilobatus sacculifer, Globoturborotalita rubescens, Globigerinella calida, Tenuitella iota, and Globigerinita glutinata, and these only differed in terms of relative abundances (community composition). Upwelling fauna was dominated by Neogloboquadrina pachyderma, Neogloboquadrina incompta, Globorotalia crassaformis, and Globorotalia inflata. Thermocline fauna was dominated by Tenuitella fleisheri, Globorotalia truncatulinoides, and Globorotalia scitula in the west and by G. scitula only in the east. The largest part of the standing stock was consistently found in the surface layer, but SST was not the main predictor of species composition either for the depth-integrated fauna across the stations or at individual depth layers. Instead, we identified a pattern of vertical stacking of different parameters controlling species composition, reflecting different aspects of the pelagic habitat. Whereas productivity appears to dominate in the mixed layer (0–60 m), physical properties (temperature, salinity) become important at intermediate depths and in the subsurface, a complex combination of factors including oxygen concentration is required to explain the assemblage composition. These results indicate that the seemingly straightforward relationship between assemblage composition and SST in sedimentary assemblages reflects vertically and seasonally integrated processes that are only indirectly linked to SST. It also implies that fossil assemblages of planktonic foraminifera should also contain a signature of subsurface processes, which could be used for paleoceanographic reconstructions.

Description: Light-use efficiency defines the ability of primary producers to convert sunlight energy to primary production and is computed as the ratio between the gross primary production and the intercepted photosynthetic active radiation. While this measure has been applied broadly within terrestrial ecology to investigate habitat resource-use efficiency, it remains underused within the aquatic realm. This report provides a conceptual framework to compute hourly and daily light-use efficiency using underwater O2 eddy covariance, a recent technological development that produces habitat-scale rates of primary production under unaltered in situ conditions. The analysis, tested on two benthic flux datasets, documents that hourly light-use efficiency may approach the theoretical limit of 0.125 O2 per photon under low-light conditions, but it decreases rapidly towards the middle of the day and is typically 10-fold lower on a 24 h basis. Overall, light-use efficiency provides a useful measure of habitat functioning and facilitates site comparison in time and space.

Description: Fishermen are known to try to avoid fishing in stormy weather, as storms pose a physical threat to fishers, their vessels, and their gear. In this article, a dataset and methods are developed to investigate the degree to which fishers avoid storms, estimate storm aversion parameters, and explore how this response varies across vessel characteristics and across regions of the United States. The data consist of vessel-level trip-taking decisions from six federal fisheries across the United States combined with marine storm warning data from the National Weather Service. The estimates of storm aversion can be used to parameterize predictive models. Fishers’ aversion to storms decreases with increasing vessel size and increases with the severity of the storm warning. This information contributes to our understanding of the risk-to-revenue trade-off that fishers evaluate every time they consider going to sea, and of the propensity of fishers to take adaptive actions to avoid facing additional physical risk.

Description: In the past decades, severe heat waves have frequently occurred in many parts of the world. These conspicuous heat waves exerted terrible influences on human health, society, the economy, agriculture, the ecosystem and so on. Based on observed daily temperatures in China, an integrated index of heat waves and extreme-temperature days was established involving the frequency, duration, intensity and scale of these events across large cities in China. Heat waves and extreme-temperature days showed an increasing trend in most regions except northwest China from 1955 to 2014. After the late 1980s, the increasing trend was more obvious than the decades before. The cities in the middle and lower reaches of the Yangtze River were threatened by the most serious heat events in the past 60 years, especially Chongqing and Changsha. Due to the subtropical monsoon climate and special terrain, Chongqing experienced the most heat events in a long period of time. In particular, there was obvious fluctuation of hot years in 31 cities, which did not continuously rise with global warming; 21 cities mainly located in the eastern and southern regions of China had an obvious rising trend; eight cities had a clear declining trend which was mainly distributed in the western and northern regions of China; and there were no extreme-temperature days in Kunming and Lhasa in the past 60 years. The study revealed an obvious differentiation of heat events for 31 cities under climate change; heat threat in most cities is increasing but declining or remaining unchanged in the other cities. The trend is likely to intensify with global warming.

Description: Sardine Sardinops sagax is an ecologically and economically important Clupeid found off the entire South African coast that includes both coastal upwelling and western boundary current systems. Although the management of the sardine fisheries historically assumed a single, panmictic population, the existence of three, semi-discrete subpopulations has recently been hypothesized. We conducted otolith δ18O and microstructure analyses to investigate nursery habitat temperatures and early life growth rates, respectively, of sardine collected from three biogeographic regions around South Africa’s coast to test that hypothesis. Analyses indicated that for both summer- and winter-captured adults and summer-captured juveniles, fishes from the west coast grew significantly slower in water that was several degrees cooler than those from the south and east coasts. This suggests that mixing of sardines between regions, particularly the west and other coasts, is relatively limited and supports the hypothesis of semi-discrete subpopulations. However, the west-south differences disappeared in the results for winter-captured juveniles, suggesting that differences in early life conditions between regions may change seasonally, and/or that all or most winter-captured juveniles originated from the west coast. Further elucidating the interactions between South African sardine subpopulations and the mechanisms thereof is important for sustainable harvesting of this species.

Description: The total Antarctic sea ice extent (SIE) experiences a distinct annual cycle, peaking in September and reaching its minimum in February. In this paper we propose a mathematical and statistical decomposition of this temporal variation in SIE. Each component is interpretable and, when combined, gives a complete picture of the variation in the sea ice. We consider timescales varying from the instantaneous and not previously defined to the multi-decadal curvilinear trend, the longest. Because our representation is daily, these timescales of variability give precise information about the timing and rates of advance and retreat of the ice and may be used to diagnose physical contributors to variability in the sea ice. We define a number of annual cycles each capturing different components of variation, especially the yearly amplitude and phase that are major contributors to SIE variation. Using daily sea ice concentration data, we show that our proposed invariant annual cycle explains 29 % more of the variation in daily SIE than the traditional method. The proposed annual cycle that incorporates amplitude and phase variation explains 77 % more variation than the traditional method. The variation in phase explains more of the variability in SIE than the amplitude. Using our methodology, we show that the anomalous decay of sea ice in 2016 was associated largely with a change of phase rather than amplitude. We show that the long term trend in Antarctic sea ice extent is strongly curvilinear and the reported positive linear trend is small and dependent strongly on a positive trend that began around 2011 and continued until 2016.

Description: The CloudRoots field experiment was designed to obtain a comprehensive observational dataset that includes soil, plant, and atmospheric variables to investigate the interaction between a heterogeneous land surface and its overlying atmospheric boundary layer at the sub-hourly and sub-kilometre scale. Our findings demonstrate the need to include measurements at leaf level to better understand the relations between stomatal aperture and evapotranspiration (ET) during the growing season at the diurnal scale. Based on these observations, we obtain accurate parameters for the mechanistic representation of photosynthesis and stomatal aperture. Once the new parameters are implemented, the model reproduces the stomatal leaf conductance and the leaf-level photosynthesis satisfactorily. At the canopy scale, we find a consistent diurnal pattern on the contributions of plant transpiration and soil evaporation using different measurement techniques. From highly resolved vertical profile measurements of carbon dioxide (CO2) and other state variables, we infer a profile of the CO2 assimilation in the canopy with non-linear variations with height. Observations taken with a laser scintillometer allow us to quantify the non-steadiness of the surface turbulent fluxes during the rapid changes driven by perturbation of photosynthetically active radiation by cloud flecks. More specifically, we find 2 min delays between the cloud radiation perturbation and ET. To study the relevance of advection and surface heterogeneity for the land–atmosphere interaction, we employ a coupled surface–atmospheric conceptual model that integrates the surface and upper-air observations made at different scales from leaf to the landscape. At the landscape scale, we calculate a composite sensible heat flux by weighting measured fluxes with two different land use categories, which is consistent with the diurnal evolution of the boundary layer depth. Using sun-induced fluorescence measurements, we also quantify the spatial variability of ET and find large variations at the sub-kilometre scale around the CloudRoots site. Our study shows that throughout the entire growing season, the wide variations in stomatal opening and photosynthesis lead to large diurnal variations of plant transpiration at the leaf, plant, canopy, and landscape scales. Integrating different advanced instrumental techniques with modelling also enables us to determine variations of ET that depend on the scale where the measurement were taken and on the plant growing stage.

Description: In the western Mediterranean Sea, Levantine intermediate waters (LIW), which circulate below the surface productive zone, progressively accumulate nutrients along their pathway from the Tyrrhenian Sea to the Algerian Basin. This study addresses the role played by diffusion in the nutrient enrichment of the LIW, a process particularly relevant inside step-layer structures extending down to deep waters – structures known as thermohaline staircases. Profiling float observations confirmed that staircases develop over epicentral regions confined in large-scale circulation features and maintained by saltier LIW inflows on the periphery. Thanks to a high profiling frequency over the 4-year period 2013–2017, float observations reveal the temporal continuity of the layering patterns encountered during the cruise PEACETIME and document the evolution of layer properties by about +0.06 ∘C in temperature and +0.02 in salinity. In the Algerian Basin, the analysis of in situ lateral density ratios untangled double-diffusive convection as a driver of thermohaline changes inside epicentral regions and isopycnal diffusion as a driver of heat and salt exchanges with the surrounding sources. In the Tyrrhenian Sea, the nitrate flux across thermohaline staircases, as opposed to the downward salt flux, contributes up to 25 % of the total nitrate pool supplied to the LIW by vertical transfer. Overall, however, the nutrient enrichment of the LIW is driven mostly by other sources, coastal or atmospheric, as well as by inputs advected from the Algerian Basin.

Description: We present a high-resolution spatial study of ocean surface carbon dioxide partial pressure (pCO2), temperature and salinity coupled with a seismic survey performed in subpolar waters with a variable presence of glaciers along the coastal margins of Admiralty Bay and the Bransfield Strait, northern Antarctic Peninsula, during the late spring season. Three zones were identified in this bay. The shallow and relatively fresh SHALLOW GLACIER THAW zone in the inner portion of the bay had high freshwater inputs from active glacial meltwater channels, representing higher pCO2 levels (median ~438 μatm) than the shallow and relatively salty SHALLOW zone without glaciers along the margins and dominated by macroalgae communities at the bottom, which showed relatively low pCO2 levels (median ~371 μatm). The deep and relatively salty CENTRE zone was highly influenced by seawater intrusions from the Bransfield Strait, representing intermediate pCO2 levels (median ~397 μatm). The net sea-air CO2 fluxes in late spring obtained from the high-resolution surface survey in Admiralty Bay indicate a condition of near neutral air-sea CO2 flux, with a median (25–75% interquartile range) value of -0.07 mmol m-2 day-1 (ranging from -12.21 to +4.33 mmol m-2 day-1), contrasting with the slight source to the atmosphere estimated from measurements only in the CENTRE zone. This finding suggests that temperature-sensitive metabolic and physical-chemical processes may cause significant variability in the ocean surface distribution of CO2 over short shoreline distances in the northern Antarctic Peninsula.

Description: The invasion of aquifer microbial communities by aboveground microorganisms, a phenomenon known as community coalescence, is likely to be exacerbated in groundwaters fed by stormwater infiltration systems (SISs). Here, the incidence of this increased connectivity with upslope soils and impermeabilized surfaces was assessed through a meta-analysis of 16S rRNA gene libraries. Specifically, DNA sequences encoding 16S rRNA V5-V6 regions from free-living and attached aquifer bacteria (i.e., water and biofilm samples) were analysed upstream and downstream of a SIS and compared with those from bacterial communities from watershed runoffs and surface sediments from the SIS detention and infiltration basins. Significant bacterial transfers were inferred by the SourceTracker Bayesian approach, with 23 % to 57 % of the aquifer bacterial biofilms being composed of taxa from aboveground sediments and urban runoffs. Sediments from the detention basin were found more significant contributors of taxa involved in the buildup of these biofilms than soils from the infiltration basin. Inferred taxa among the coalesced biofilm community were predicted to be high in hydrocarbon degraders such as Sphingobium and Nocardia. The 16S rRNA-based bacterial community structure of the downstream-SIS aquifer waters showed lower coalescence with aboveground taxa (8 % to 38 %) than those of biofilms and higher numbers of taxa predicted to be involved in the N and S cycles. A DNA marker named tpm enabled the tracking of bacterial species from 24 genera including Pseudomonas, Aeromonas and Xanthomonas, among these communities. Several tpm sequence types were found to be shared between the aboveground and aquifer samples. Reads related to Pseudomonas were allocated to 50 species, of which 16 were found in the aquifer samples. Several of these aquifer species were found to be involved in denitrification but also hydrocarbon degradation (P. aeruginosa, P. putida and P. fluorescens). Some tpm sequence types allocated to P. umsongensis and P. chengduensis were found to be enriched among the tpm-harbouring bacteria, respectively, of the aquifer biofilms and waters. Reads related to Aeromonas were allocated to 11 species, but only those from A. caviae were recovered aboveground and in the aquifer samples. Some tpm sequence types of the X. axonopodis phytopathogen  were recorded in higher proportions among the tpm-harbouring bacteria of the aquifer waters than in the aboveground samples. A significant coalescence of microbial communities from an urban watershed with those of an aquifer was thus observed, and recent aquifer biofilms were found to be significantly colonized by runoff-opportunistic taxa able to use urban C sources from aboveground compartments.

Description: Landfast sea ice (fast ice) attached to Antarctic (near-)coastal elements is a critical component of the local physical and ecological systems. Through its direct coupling with the atmosphere and ocean, fast-ice properties are also a potential indicator of processes related to a changing climate. However, in situ fast-ice observations in Antarctica are extremely sparse because of logistical challenges and harsh environmental conditions. Since 2010, a monitoring program observing the seasonal evolution of fast ice in Atka Bay has been conducted as part of the Antarctic Fast Ice Network (AFIN). The bay is located on the northeastern edge of Ekström Ice Shelf in the eastern Weddell Sea, close to the German wintering station Neumayer III. A number of sampling sites have been regularly revisited each year between annual ice formation and breakup to obtain a continuous record of sea-ice and sub-ice platelet-layer thickness, as well as snow depth and freeboard across the bay. Here, we present the time series of these measurements over the last 9 years. Combining them with observations from the nearby Neumayer III meteorological observatory as well as auxiliary satellite images enables us to relate the seasonal and interannual fast-ice cycle to the factors that influence their evolution. On average, the annual consolidated fast-ice thickness at the end of the growth season is about 2 m, with a loose platelet layer of 4 m thickness beneath and 0.70 m thick snow on top. Results highlight the predominately seasonal character of the fast-ice regime in Atka Bay without a significant interannual trend in any of the observed variables over the 9-year observation period. Also, no changes are evident when comparing with sporadic measurements in the 1980s and 1990s. It is shown that strong easterly winds in the area govern the year-round snow distribution and also trigger the breakup of fast ice in the bay during summer months. Due to the substantial snow accumulation on the fast ice, a characteristic feature is frequent negative freeboard, associated flooding of the snow–ice interface, and a likely subsequent snow ice formation. The buoyant platelet layer beneath negates the snow weight to some extent, but snow thermodynamics is identified as the main driver of the energy and mass budgets for the fast-ice cover in Atka Bay. The new knowledge of the seasonal and interannual variability of fast-ice properties from the present study helps to improve our understanding of interactions between atmosphere, fast ice, ocean, and ice shelves in one of the key regions of Antarctica and calls for intensified multidisciplinary studies in this region.

Description: Storm tides are a major hazard for the German North Sea coasts. For coastal protection and economic activities, planning information on the probability and magnitude of extreme storm tides and their possible future changes is important. This study focuses on the most extreme events and examines whether they could have become more severe under slightly different conditions while still remaining within physical plausibility. In the face of a limited number of observational data on very severe events, an extensive set of model data is used to extract most extreme storm tide events for locations in the German Bight, in particular Borkum and the Ems estuary. The data set includes water levels and respective atmospheric conditions from a hindcast and future climate realizations without sea level rise describing today's and possible future conditions. A number of very severe events with water levels exceeding those measured near Borkum since 1906 are identified in the data set. A possible further amplification of the highest events is investigated by simulating these events for the North Sea with different phase lags between the astronomical tide given at the open model boundaries and the wind forcing. It is found that superposition of spring tide conditions, different timing of the astronomical high water and atmospheric conditions during the highest storm event would cause an enhancement of the highest water level up to about 50 cm. The water levels of the two highest events from the data set are used to analyse the effects in the Ems estuary using a high-resolution model of the German Bight. Additionally, the influences of an extreme river runoff and of sea level rise are studied. The extreme river runoff of 1200 m3 s−1 increases the highest water levels by several decimetres in the narrow upstream part of the Ems estuary. This effect diminishes downstream. The sea level rise increases the water level in the downstream part of the Ems estuary by the amount applied at the model boundary to the North Sea. In the upstream part, its influence on the water level decreases. This study may serve as a first step towards an impact assessment for severe storm tides and towards implications for coastal zone management in times of climate change.

Description: Peatlands store ∼ 20 %–30 % of the global soil organic carbon stock and are an important source of dissolved organic carbon (DOC) for inland waters. Recent improvements for in situ optical monitoring revealed that the DOC concentration in streams draining peatlands is highly variable, showing seasonal variation and short and intense DOC concentration peaks. This study aimed to statistically determine the variables driving stream DOC concentration variations at seasonal and event scales. Two mountainous peatlands (one fen and one bog) were monitored in the French Pyrenees to capture their outlet DOC concentration variability at a high-frequency rate (30 min). Abiotic variables including precipitation, stream temperature and water level, water table depth, and peat water temperature were also monitored at high frequency and used as potential predictors to explain DOC concentration variability. Results show that at both sites DOC concentration time series can be decomposed into a seasonal baseline interrupted by many short and intense peaks of higher concentrations. The DOC concentration baseline is driven, at the seasonal scale, by peat water temperature. At the event scale, DOC concentration increases are mostly driven by a rise in the water table within the peat at both sites. Univariate linear models between DOC concentration and peat water temperature or water table increases show greater efficiency at the fen site. Water recession times were derived from water level time series using master recession curve coefficients. They vary greatly between the two sites but also within one peatland site. They partly explain the differences between DOC dynamics in the studied peatlands, including peat porewater DOC concentrations and the links between stream DOC concentration and water table rise within the peatlands. This highlights that peatland complexes are composed of a mosaic of heterogeneous peat units distinctively producing or transferring DOC to streams.

Description: Submarine groundwater discharge (SGD) is an important gateway for nutrients and pollutants from land to sea. While understanding SGD is crucial for managing nearshore ecosystems and coastal freshwater reserves, studying this discharge is complicated by its occurrence at the limit between land and sea, a dynamic environment. This practical difficulty is exacerbated by the significant spatial and temporal variability. Therefore, to capture the magnitude of SGD, a variety of techniques and measurements, applied over multiple periods, is needed. Here, we combine several geophysical methods to detect zones of fresh submarine groundwater discharge (FSGD) in the intertidal zone, upper beach, dunes, and shallow coastal area. Both terrestrial electrical-resistivity tomography (ERT; roll-along) and marine continuous resistivity profiling (CRP) are used from the shallow continental shelf up to the dunes and combined with frequency domain electromagnetic (FDEM) mapping in the intertidal zone. In particular, we apply an estimation of robust apparent electrical conductivity (rECa) from FDEM data to provide reliable lateral and vertical discrimination of FSGD zones. The study area is a very dynamic environment along the North Sea, characterized by semi-diurnal tides between 3 and 5 m. CRP is usually applied in calmer conditions, but we prove that such surveys are possible and provide additional information to primarily land-bound ERT surveying. The 2D inversion models created from ERT and CRP data clearly indicate the presence of FSGD on the lower beach or below the low-water line. This discharge originates from a potable freshwater lens below the dunes and flows underneath a thick saltwater lens, present from the dunes to the lower sandy beach, which is fully observed with ERT. Freshwater outflow intensity has increased since 1980, due to a decrease of groundwater pumping in the dunes. FDEM mapping at two different times reveals discharge at the same locations, clearly displays the lateral variation of the zone of discharge, and suggests that FSGD is stronger at the end of winter compared to the beginning of autumn. ERT, CRP, and FDEM are complementary tools in the investigation of SGD. They provide a high-resolution 3D image of the saltwater and freshwater distribution in the phreatic coastal aquifer over a relatively large area, both off- and onshore.

Description: Although luminescence sensitivity of quartz grains of desert sands has been used in discriminating provenance, it still remains unclear about its spatiotemporal variations and climatic implications. In this paper, the luminescence sensitivity of quartz grains from the northern margin of the Chinese Loess Plateau (CLP) was studied using single-aliquot optically stimulated luminescence (OSL) and “pseudo” single-grain OSL measurements. Our results indicate that the OSL sensitivities have lower values in sand/loess beds and higher values in paleosols. We suggest that the variations in OSL sensitivity of quartz grains with depth on the CLP are mainly influenced by the origin of the quartz grains as they are related to the loess-sized material production processes and the migration of desert regions. More quartz grains of glacial origin with lower luminescence sensitivity, together with the reduced durations of irradiation and exposure cycles induced by shorter transport distance due to desert expansion, account for the lower luminescence sensitivity of glacial periods. Moreover, both the mountain processes and the retreat–advance of deserts are ultimately related to climatic changes, therefore, the orbital scale variations of luminescence sensitivity are controlled by glacial–interglacial oscillations on the CLP.

Description: The Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) mission is one of six high-priority candidate missions (HPCMs) under consideration by the European Commission to enlarge the Copernicus Space Component. Together, the high-priority candidate missions fill gaps in the measurement capability of the existing Copernicus Space Component to address emerging and urgent user requirements in relation to monitoring anthropogenic CO2 emissions, polar environments, and land surfaces. The ambition is to enlarge the Copernicus Space Component with the high-priority candidate missions in the mid-2020s to provide enhanced continuity of services in synergy with the next generation of the existing Copernicus Sentinel missions. CRISTAL will carry a dual-frequency synthetic-aperture radar altimeter as its primary payload for measuring surface height and a passive microwave radiometer to support atmospheric corrections and surface-type classification. The altimeter will have interferometric capabilities at Ku-band for improved ground resolution and a second (non-interferometric) Ka-band frequency to provide information on snow layer properties. This paper outlines the user consultations that have supported expansion of the Copernicus Space Component to include the high-priority candidate missions, describes the primary and secondary objectives of the CRISTAL mission, identifies the key contributions the CRISTAL mission will make, and presents a concept – as far as it is already defined – for the mission payload.

Description: Für die Verortung der deutschen akademischen Humangeographie im Geflecht zwischen wissenschaftlicher Praxis, theoretischen Propositionen und Lehralltag war der Geographentag in Kiel im Jahre 1969 ein Meilenstein. Anlässlich der Erinnerung an den Ort und die Debatten vor 50 Jahren wurde wiederum Kiel im Jahre 2019 zu einem Ort der Reflektion. Der hier vorliegende Beitrag versucht in einer bewusst persönlich formulierten Art die Impulse, die von „Kiel 1969“ ausgingen, im universitären Alltag des Geographischen Institutes der TU München in den 1980er Jahren zu verorten und hierdurch gewissermaßen zu relativieren. Hierdurch entsteht ein differenziertes Bild von richtungsweisenden Veränderungen und verharrenden Strukturen, welche ineinander verwoben die damals überregional bekannte Münchener Sozialgeographie charakterisierten – und für die deutschsprachige Humangeographie über die speziell Münchner Zustände hinaus bezeichnend waren.

Description: Per capita arable land is decreasing due to the rapidly increasing population, and fresh water is becoming scarce and more expensive. Therefore, farmers should continue to use technology and innovative solutions to improve efficiency, save input costs, and optimise environmental resources (such as water). In the case study presented in this paper, the Global Navigation Satellite System interferometric reflectometry (GNSS-IR) technique was used to monitor soil moisture during 66 d, from 3 December 2018 to 6 February 2019, in the installations of the Cajamar Centre of Experiences, Paiporta, Valencia, Spain. Two main objectives were pursued. The first was the extension of the technique to a multi-constellation solution using GPS, GLONASS, and GALILEO satellites, and the second was to test whether mass-market sensors could be used for this technique. Both objectives were achieved. At the same time that the GNSS observations were made, soil samples taken at 5 cm depth were used for soil moisture determination to establish a reference data set. Based on a comparison with that reference data set, all GNSS solutions, including the three constellations and the two sensors (geodetic and mass market), were highly correlated, with a correlation coefficient between 0.7 and 0.85.

Description: Two satellite datasets are used to characterize winter landfast first-year sea-ice (FYI), deformed FYI (DFYI) and multiyear sea-ice (MYI) roughness in the Canadian Arctic Archipelago (CAA): (1) optical Multi-angle Imaging SpectroRadiometer (MISR) and (2) synthetic aperture radar Sentinel-1. The Normalized Difference Angular Index (NDAI) roughness proxy derived from MISR, and backscatter from Sentinel-1 are intercompared. NDAI and backscatter are also compared to surface roughness derived from an airborne LiDAR track covering a subset of FYI and MYI (no DFYI). Overall, NDAI and backscatter are significantly positively correlated when all ice type samples are considered. When individual ice types are evaluated, NDAI and backscatter are only significantly correlated for DFYI. Both NDAI and backscatter are correlated with LiDAR-derived roughness (r = 0.71 and r = 0.74, respectively). The relationship between NDAI and roughness is greater for MYI than FYI, whereas for backscatter and ice roughness, the relationship is greater for FYI than MYI. Linear regression models are created for the estimation of FYI and MYI roughness from NDAI, and FYI roughness from backscatter. Results suggest that using a combination of Sentinel-1 backscatter for FYI and MISR NDAI for MYI may be optimal for mapping winter sea-ice roughness in the CAA.

Description: Drumlins form at the ice/bed interface through subglacial processes that are not directly observable. The internal stratigraphy of drumlins provides insight into how they developed and associated subglacial processes, but traditional stratigraphic logging techniques are limited to natural exposures and excavations. Using ground-penetrating radar, we imaged the internal stratigraphy of seven drumlins from a recently exposed drumlin field in the forefield of Múlajökull, Iceland. Data were collected with 100 and 200 MHz antennas with maximum resolvable depths of 8 and 4 m, respectively. Longitudinal echograms contained coherent down-ice dipping reflectors over the lengths of the drumlins. Near the drumlin heads (i.e., stoss sides), down-glacier dipping beds lie at high angles to the surface, whereas on the lee sides, the down-glacier dipping beds lie at low angles, or conform, to drumlin surfaces. Transverse echograms exhibited unconformities along the flanks of drumlin heads and conformable bedding across the lee side widths of the drumlins. These observations were ground-truthed with stratigraphic logs from a subset of drumlins and good agreement was found. The stratigraphic patterns support previous conclusions that drumlins at Múlajökull formed on a deformable bed through both depositional and erosional processes which may alternate between its surge and quiescent phases.

Description: Ancient cities are excellent spatiotemporal indicators for the study of historical human activities and environmental change. The ancient city of Sanchahe is located at the southern margin of the Mu Us Desert, China. It is an ideal location for studying the complex relationships between historical desertification and human activities. Field observations of the ancient city walls, a well, and a spring, as well as 14C dating, grain size, spatial analysis of archaeological sites, and analyses of historical seismicity, indicated that neotectonics may have contributed to crustal uplift and accelerated fluvial incision of the Wuding River. This rapid incision caused a decline in groundwater levels, which is an important reason for the irreversible environmental degradation around Sanchahe city over the past 800 yr. This study provides new evidence for such environmental degradation and may contribute to a better understanding of historical desertification in the Mu Us Desert.

Description: CerealsDB (www.cerealsdb.uk.net) is an online repository of mainly hexaploid wheat (Triticum aestivum) single nucleotide polymorphisms (SNPs) and genotyping data. The CerealsDB website has been designed to enable wheat breeders and scientists to select the appropriate markers for research breeding tasks, such as marker-assisted selection. We report a large update of genotyping information for over 6000 wheat accessions and describe new webtools for exploring and visualizing the data. We also describe a new database of quantitative trait loci that links phenotypic traits to CerealsDB SNP markers and allelic scores for each of those markers. CerealsDB is an open-access website that hosts information on wheat SNPs considered useful for both plant breeders and research scientists. The latest CerealsDB database is available at https://www.cerealsdb.uk.net/cerealgenomics/CerealsDB/indexNEW.php.

Description: Anoxic sediments, as compared to oxic settings, encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to structural changes of the organic molecules themselves, as well as cross-linking between them (e.g., through reactive sulfur species). Both processes transform the original biomolecules into geomolecules. For the oxic environment, these intermolecular and intramolecular transformations also operate, but cross-linking may be less important since the labile, reactive component is rapidly removed. As such, one may expect a structurally better preservation of the more refractory initial biomolecules in the oxic environment. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species-specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thalassiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene (∼40 Ma) sulfidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical and show no signs of morphological modification, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infrared analyses show that their macromolecular characteristics are strongly different. Comparison with recent cysts shows that the cysts deposited in the sulfidic Rhine Graben show a strong additional contribution of long-chain aliphatic moieties and thus less diagenetic intermolecular cross-linking. The presence of organic sulfur identifies natural volcanization as one of the diagenetic processes. Furthermore, we observe a loss of bound oxygen and no trace of the original carbohydrate signature of the cyst wall biomacromolecule. The material deposited in the oxic sediments of the Kerguelen Plateau shows no traces of sulfurization. It shows a minor contribution of short carbon chains only and thus less diagenetic intermolecular cross-linking. Furthermore, a carbohydrate signature was still preserved evidencing a better molecular preservation of the initial biomacromolecule, supporting our initial hypothesis. This shows that excellent morphological preservation does not imply excellent chemical preservation. It also leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter and its isotopic signature.

Description: Progress towards ecosystem-based fisheries management calls for useful tools to prioritize actions. To select suitable methods for local circumstances, evaluating approaches used in other jurisdictions can be a cost-effective first step. We tested Productivity Susceptibility Analysis (PSA) to assess the potential vulnerability of the marine fish community in the Skagerrak–Kattegat (Eastern North Sea) to possible interactions with all Swedish fisheries operating in the area. This analysis combines attributes for a species productivity with attributes related to the susceptibility to capture to quantify a single score for vulnerability: high, medium, or low risk. Results indicate that demersal trawl and gillnet fisheries were associated with the highest risk levels if interaction occurs, i.e. having the highest prevalence of species with potentially high vulnerability to the fisheries. Mixed results were seen when comparing the assessment results with available data. The main benefit of utilizing PSA in the area is the comprehensiveness of the assessment, including data-deficient fisheries and species. Drawbacks include potential overestimation of actual risks. Overall, together with available data, PSA in the studied area provides a comprehensive map of potential risks for further actions and may progress a science-based, precautionary management of the area.

Description: While fisheries provide food and employment for hundreds of millions of people, they also can have significant impact on biodiversity. We explore the potential of area-based fisheries management to simultaneously maintain biodiversity and high levels of sustainable food production. We used two illustrative examples of fisheries that have different gear types, areas, and species to evaluate the trade-off between biodiversity and harvest. We calculate the optimal effort by gear and area that maximizes a weighted objective function of biodiversity and harvest, ranging from 100% of the weight on harvest to 100% on biodiversity. We found for both case studies that the trade-off was highly convex, with win–win solutions allowing for high levels of both fishery harvest and conservation. This is achieved by reducing or eliminating fishing effort that negatively impacts high conservation value species while maintaining fishing effort with gears and in areas where there is low conservation impact. We suggest that, in most fisheries, such situations can be found and that effective area-based management can provide for high levels of biodiversity protection and food production.

Description: A Fast Ice Prediction System (FIPS) was constructed and is the first regional land-fast sea-ice forecasting system for the Antarctic. FIPS had two components: (1) near-real-time information on the ice-covered area from MODIS and SAR imagery that revealed, tidal cracks, ridged and rafted ice regions; (2) a high-resolution 1-D thermodynamic snow and ice model (HIGHTSI) that was extended to perform a 2-D simulation on snow and ice evolution using atmospheric forcing from ECMWF: either using ERA-Interim reanalysis (in hindcast mode) or HERS operational 10-day predictions (in forecast mode). A hindcast experiment for the 2015 season was in good agreement with field observations, with a mean bias of 0.14 ± 0.07 m and a correlation coefficient of 0.98 for modeled ice thickness. The errors are largely caused by a cold bias in the atmospheric forcing. The thick snow cover during the 2015 season led to modeled formation of extensive snow ice and superimposed ice. The first FIPS operational service was performed during the 2017/18 season. The system predicted a realistic ice thickness and onset of snow surface melt as well as the area of internal ice melt. The model results on the snow and ice properties were considered by the captain of R/V Xuelong when optimizing a low-risk route for on-ice transportation through fast ice to the coastal Zhongshan Station.

Description: The most prolific acacias in southern Europe (Acacia dealbata, A. melanoxylon and A. longifolia) are rapidly spreading in its westernmost area: Portugal and NW Spain, where congeners with invasion potential are already established. We performed a bibliographic search of acacia invasions in southern Europe and used spatial data on acacia distribution and abiotic parameters in Iberia to check the influence of abiotic factors on acacia invasion. According to our results, in Iberia A. dealbata and A. melanoxylon seem limited by high soil pH (pHCaCl2〉5.5), frequent frosts (〉21 to 40 d yr−1) and low annual precipitation (

Description: The evolution of melt ponds on Arctic sea ice in summer is one of the main factors that affect sea-ice albedo and hence the polar climate system. Due to the different spectral properties of open water, melt pond and sea ice, the melt pond fraction (MPF) can be retrieved using a fully constrained least-squares algorithm, which shows a high accuracy with root mean square error ~0.06 based on the validation experiment using WorldView-2 image. In this study, the evolution of ponds on first-year and multiyear ice in the Canadian Arctic Archipelago was compared based on Sentinel-2 and Landsat 8 images. The relationships of pond coverage with air temperature and albedo were analysed. The results show that the pond coverage on first-year ice changed dramatically with seasonal maximum of 54%, whereas that on multiyear ice changed relatively flat with only 30% during the entire melting period. During the stage of pond formation, the ponds expanded rapidly when the temperature increased to over 0°C for three consecutive days. Sea-ice albedo shows a significantly negative correlation (R = −1) with the MPF in melt season and increases gradually with the refreezing of ponds and sea ice.

Description: We report apatite fission-track and 10Be terrestrial cosmogenic nuclide (TCN) dating of 14 moraine boulders originating from inland Terre Adélie, East Antarctica. These data show cooling of the Proterozoic Terre Adélie craton at 〈 ~120°C between 350 and 300 Ma, suggesting 〉 4 km temperate glacial erosion during the Late Palaeozoic Ice Age, followed by nearly null Mesozoic erosion and low glacial erosion (〈 2 km) in the Cenozoic. Based on glacial flux maps, the origin of the boulders may be located ~400 km upstream. Preliminary TCN (10Be) datings of moraine boulders cluster within the last 30 ka. Cosmogenic ages from the Lacroix Nunatak suggest a main deglaciation after the Younger Dryas at c. 10 ka, while those of Cap Prud'homme mostly cluster at 0.6 ka, in agreement with an exhumation of boulders during the Little Ice Age.

Description: Glacial environments exhibit temporally variable microseismicity. To investigate how microseismicity influences event detection, we implement two noise-adaptive digital power detectors to process seismic data from Taylor Glacier, Antarctica. We add scaled icequake waveforms to the original data stream, run detectors on the hybrid data stream to estimate reliable detection magnitudes and compare analytical magnitudes predicted from an ice crack source model. We find that detection capability is influenced by environmental microseismicity for seismic events with source size comparable to thermal penetration depths. When event counts and minimum detectable event sizes change in the same direction (i.e. increase in event counts and minimum detectable event size), we interpret measured seismicity changes as ‘true’ seismicity changes rather than as changes in detection. Generally, one detector (two degree of freedom (2dof)) outperforms the other: it identifies more events, a more prominent summertime diurnal signal and maintains a higher detection capability. We conclude that real physical processes are responsible for the summertime diurnal inter-detector difference. One detector (3dof) identifies this process as environmental microseismicity; the other detector (2dof) identifies it as elevated waveform activity. Our analysis provides an example for minimizing detection biases and estimating source sizes when interpreting temporal seismicity patterns to better infer glacial seismogenic processes.

Description: Boron isotope systematics of planktonic foraminifera from core-top sediments and culture experiments have been studied to investigate the sensitivity of δ11B of calcite tests to seawater pH. However, our knowledge of the relationship between δ11B and pH remains incomplete for many taxa. Thus, to expand the potential scope of application of this proxy, we report δ11B data for seven different species of planktonic foraminifera from sediment core tops. We utilize a method for the measurement of small samples of foraminifera and calculate the δ11B-calcite sensitivity to pH for Globigerinoides ruber, Trilobus sacculifer (sacc or without sacc), Orbulina universa, Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, Globorotalia menardii, and Globorotalia tumida, including for unstudied core tops and species. These taxa have diverse ecological preferences and are from sites that span a range of oceanographic regimes, including some that are in regions of air–sea equilibrium and others that are out of equilibrium with the atmosphere. The sensitivity of δ11Bcarbonate to δ11Bborate (e.g., Δδ11Bcarbonate∕Δδ11Bborate) in core tops is consistent with previous studies for T. sacculifer and G. ruber and close to unity for N. dutertrei, O. universa, and combined deep-dwelling species. Deep-dwelling species closely follow the core-top calibration for O. universa, which is attributed to respiration-driven microenvironments likely caused by light limitation and/or symbiont–host interactions. Our data support the premise that utilizing boron isotope measurements of multiple species within a sediment core can be utilized to constrain vertical profiles of pH and pCO2 at sites spanning different oceanic regimes, thereby constraining changes in vertical pH gradients and yielding insights into the past behavior of the oceanic carbon pumps.

Description: Carbon–nitrogen (C–N) interactions regulate N availability for plant growth and for emissions of nitrous oxide (N2O) and the uptake of carbon dioxide. Future projections of these terrestrial greenhouse gas fluxes are strikingly divergent, leading to major uncertainties in projected global warming. Here we analyse the large increase in terrestrial N2O emissions over the past 21 000 years as reconstructed from ice-core isotopic data and presented in part 1 of this study. Remarkably, the increase occurred in two steps, each realized over decades and within a maximum of 2 centuries, at the onsets of the major deglacial Northern Hemisphere warming events. The data suggest a highly dynamic and responsive global N cycle. The increase may be explained by an increase in the flux of reactive N entering and leaving ecosystems or by an increase in N2O yield per unit N converted. We applied the LPX-Bern dynamic global vegetation model in deglacial simulations forced with Earth system model climate data to investigate N2O emission patterns, mechanisms, and C–N coupling. The N2O emission changes are mainly attributed to changes in temperature and precipitation and the loss of land due to sea-level rise. LPX-Bern simulates a deglacial increase in N2O emissions but underestimates the reconstructed increase by 47 %. Assuming time-independent N sources in the model to mimic progressive N limitation of plant growth results in a decrease in N2O emissions in contrast to the reconstruction. Our results appear consistent with suggestions of (a) biological controls on ecosystem N acquisition and (b) flexibility in the coupling of the C and N cycles during periods of rapid environmental change. A dominant uncertainty in the explanation of the reconstructed N2O emissions is the poorly known N2O yield per N lost through gaseous pathways and its sensitivity to soil conditions. The deglacial N2O record provides a constraint for future studies.

Description: Seamounts represent ideal systems to study the influence and interdependency of environmental gradients at a single geographic location. These topographic features represent a prominent habitat for various forms of life, including microbiota and macrobiota, spanning benthic as well as pelagic organisms. While it is known that seamounts are globally abundant structures, it still remains unclear how and to which extent the complexity of the sea floor is intertwined with the local oceanographic mosaic, biogeochemistry, and microbiology of a seamount ecosystem. Along these lines, the present study aimed to explore whether and to what extent seamounts can have an imprint on the microbial community composition of seawater and of sessile benthic invertebrates, sponges. For our high-resolution sampling approach of microbial diversity (16S rRNA gene amplicon sequencing) along with measurements of inorganic nutrients and other biogeochemical parameters, we focused on the Schulz Bank seamount ecosystem, a sponge ground ecosystem which is located on the Arctic Mid-Ocean Ridge. Seawater samples were collected at two sampling depths (mid-water, MW, and near-bed water, BW) from a total of 19 sampling sites. With a clustering approach we defined microbial microhabitats within the pelagic realm at Schulz Bank, which were mapped onto the seamount's topography and related to various environmental parameters (such as suspended particulate matter, SPM; dissolved inorganic carbon, DIC; silicate, SiO4-; phosphate, PO43-; ammonia, NH4+; nitrate, NO32-; nitrite, NO2-; depth; and dissolved oxygen, O2). The results of our study reveal a “seamount effect” (sensu stricto) on the microbial mid-water pelagic community at least 200 m above the sea floor. Further, we observed a strong spatial heterogeneity in the pelagic microbial landscape across the seamount, with planktonic microbial communities reflecting oscillatory and circulatory water movements, as well as processes of bentho-pelagic coupling. Depth, NO32-, SiO4-, and O2 concentrations differed significantly between the determined pelagic microbial clusters close to the sea floor (BW), suggesting that these parameters were presumably linked to changes in microbial community structures. Secondly, we assessed the associated microbial community compositions of three sponge species along a depth gradient of the seamount. While sponge-associated microbial communities were found to be mainly species-specific, we also detected significant intra-specific differences between individuals, depending on the pelagic near-bed cluster they originated from. The variable microbial phyla (i.e. phyla which showed significant differences across varying depth, NO32-, SiO4-, O2 concentrations, and different from local seawater communities) were distinct for every sponge species when considering average abundances per species. Variable microbial phyla included representatives of both those taxa traditionally counted for the variable community fraction and taxa counted traditionally for the core community fraction. Microbial co-occurrence patterns for the three examined sponge species Geodia hentscheli, Lissodendoryx complicata, and Schaudinnia rosea were distinct from each other. Over all, this study shows that topographic structures such as the Schulz Bank seamount can have an imprint (seamount effect sensu lato) on both the microbial community composition of seawater and sessile benthic invertebrates such as sponges by an interplay between the geology, physical oceanography, biogeochemistry, and microbiology of seamounts.

Description: Repeatability of study setups and reproducibility of research results by underlying data are major requirements in science. Until now, abstract models for describing the structural logic of studies in environmental sciences are lacking and tools for data management are insufficient. Mandatory for repeatability and reproducibility is the use of sophisticated data management solutions going beyond data file sharing. Particularly, it implies maintenance of coherent data along workflows. Design data concern elements from elementary domains of operations being transformation, measurement and transaction. Operation design elements and method information are specified for each consecutive workflow segment from field to laboratory campaigns. The strict linkage of operation design element values, operation values and objects is essential. For enabling coherence of corresponding objects along consecutive workflow segments, the assignment of unique identifiers and the specification of their relations are mandatory. The abstract model presented here addresses these aspects, and the software DiversityDescriptions (DWB-DD) facilitates the management of thusly connected digital data objects and structures. DWB-DD allows for an individual specification of operation design elements and their linking to objects. Two workflow design use cases, one for DNA barcoding and another for cultivation of fungal isolates, are given. To publish those structured data, standard schema mapping and XML-provision of digital objects are essential. Schemas useful for this mapping include the Ecological Markup Language, the Schema for Meta-omics Data of Collection Objects and the Standard for Structured Descriptive Data. Data pipelines with DWB-DD include the mapping and conversion between schemas and functions for data publishing and archiving according to the Open Archival Information System standard. The setting allows for repeatability of study setups, reproducibility of study results and for supporting work groups to structure and maintain their data from the beginning of a study. The theory of ‘FAIR++’ digital objects is introduced.

Description: Projecting the spatiotemporal changes in water resources under a no-analog future climate requires physically based integrated hydrologic models which simulate the transfer of water and energy across the earth's surface. These models show promise in the context of unprecedented climate extremes given their reliance on the underlying physics of the system as opposed to empirical relationships. However, these techniques are plagued by several sources of uncertainty, including the inaccuracy of input datasets such as meteorological forcing. These datasets, usually derived from climate models or satellite-based products, are typically only resolved on the order of tens to hundreds of kilometers, while hydrologic variables of interest (e.g., discharge and groundwater levels) require a resolution at much smaller scales. In this work, a high-resolution hydrologic model is forced with various resolutions of meteorological forcing (0.5 to 40.5 km) generated by a dynamical downscaling analysis from the regional climate model Weather Research and Forecasting (WRF). The Cosumnes watershed, which spans the Sierra Nevada and Central Valley interface of California (USA), exhibits semi-natural flow conditions due to its rare undammed river basin and is used here as a test bed to illustrate potential impacts of various resolutions of meteorological forcing on snow accumulation and snowmelt, surface runoff, infiltration, evapotranspiration, and groundwater levels. Results show that the errors in spatial distribution patterns impact land surface processes and can be delayed in time. Localized biases in groundwater levels can be as large as 5–10 m and 3 m in surface water. Most hydrologic variables reveal that biases are seasonally and spatially dependent, which can have serious implications for model calibration and ultimately water management decisions.

Description: The annual carbon and water dynamics of two eastern North American temperate forests were compared over a 6-year period from 2012 to 2017. The geographic location, forest age, soil, and climate were similar between the two stands; however, stand composition varied in terms of tree leaf-retention and shape strategy: one stand was a deciduous broadleaf forest, while the other was an evergreen needleleaf forest. The 6-year mean annual net ecosystem productivity (NEP) of the coniferous forest was slightly higher and more variable (218±109 g C m−2 yr−1) compared to that of the deciduous forest NEP (200±83 g C m−2 yr−1). Similarly, the 6-year mean annual evapotranspiration (ET) of the coniferous forest was higher (442±33 mm yr−1) than that of the deciduous forest (388±34 mm yr−1), but with similar interannual variability. Summer meteorology greatly impacted the carbon and water fluxes in both stands; however, the degree of response varied among the two stands. In general, warm temperatures caused higher ecosystem respiration (RE), resulting in reduced annual NEP values – an impact that was more pronounced at the deciduous broadleaf forest compared to the evergreen needleleaf forest. However, during warm and dry years, the evergreen forest had largely reduced annual NEP values compared to the deciduous forest. Variability in annual ET at both forests was related most to the variability in annual air temperature (Ta), with the largest annual ET observed in the warmest years in the deciduous forest. Additionally, ET was sensitive to prolonged dry periods that reduced ET at both stands, although the reduction at the coniferous forest was relatively larger than that of the deciduous forest. If prolonged periods (weeks to months) of increased Ta and reduced precipitation are to be expected under future climates during summer months in the study region, our findings suggest that the deciduous broadleaf forest will likely remain an annual carbon sink, while the carbon sink–source status of the coniferous forest remains uncertain.

Description: Snow instability tests provide valuable information regarding the stability of the snowpack. Test results are key data used to prepare public avalanche forecasts. However, to include them into operational procedures, a quantitative interpretation scheme is needed. Whereas the interpretation of the rutschblock test (RB) is well established, a similar detailed classification for the extended column test (ECT) is lacking. Therefore, we develop a four-class stability interpretation scheme. Exploring a large data set of 1719 ECTs observed at 1226 sites, often performed together with a RB in the same snow pit, and corresponding slope stability information, we revisit the existing stability interpretations and suggest a more detailed classification. In addition, we consider the interpretation of cases when two ECTs were performed in the same snow pit. Our findings confirm previous research, namely that the crack propagation propensity is the most relevant ECT result and that the loading step required to initiate a crack is of secondary importance for stability assessment. The comparison with the RB showed that the ECT classifies slope stability less reliably than the RB. In some situations, performing a second ECT may be helpful when the first test did not indicate rather unstable or stable conditions. Finally, the data clearly show that false-unstable predictions of stability tests outnumber the correct-unstable predictions in an environment where overall unstable locations are rare.

Description: The accuracy of sea-ice motion products provided by the National Snow and Ice Data Center (NSIDC) and the Ocean and Sea Ice Satellite Application Facility (OSI-SAF) was validated with data collected by ice drifters that were deployed in the western Arctic Ocean in 2014 and 2016. Data from both NSIDC and OSI-SAF products exhibited statistically significant (p 〈 0.001) correlation with drifter data. The OSI-SAF product tended to overestimate ice speed, while underestimation was demonstrated for the NSIDC product, especially for the melt season and the marginal ice zone. Monthly Lagrangian trajectories of ice floes were reconstructed using the products. Larger spatial variability in the deviation between NSIDC and drifter trajectories was observed than that of OSI-SAF, and seasonal variability in the deviation for NSIDC was observed. Furthermore, trajectories reconstructed using the NSIDC product were sensitive to variations in sea-ice concentration. The feasibility of using remote-sensing products to characterize sea-ice deformation was assessed by evaluating the distance between two arbitrary positions as estimated by the products. Compared with the OSI-SAF product, relative errors are lower (

Description: Aside from many well-known sources, the greenhouse gas methane (CH4) was recently discovered entrapped in the sediments of Swiss Alpine glacier forefields derived from calcareous bedrock. A first study performed in one glacial catchment indicated that CH4 was ubiquitous in sediments and rocks and was largely of thermogenic origin. Here, we present the results of a follow-up study that aimed at (1) determining the occurrence and origin of sediment-entrapped CH4 in other calcareous glacier forefields across Switzerland and (2) providing an inventory of this sediment-entrapped CH4, i.e., determining the contents and total mass of CH4 present, and its spatial distribution within and between five different Swiss glacier forefields situated on calcareous formations of the Helvetic nappes in the Central Alps. Sediment and bedrock samples were collected at high spatial resolution from the forefields of Im Griess, Griessfirn, Griessen, Wildstrubel, and Tsanfleuron glaciers, representing different geographic and geologic regions of the Helvetic nappes. We performed geochemical analyses on gas extracted from sediments and rocks, including the determination of CH4 contents, stable carbon-isotope analyses (δ13CCH4), and the determination of gas-wetness ratios (ratio of CH4 to ethane and propane contents). To estimate the total mass of CH4 entrapped in glacier-forefield sediments, the total volume of sediment was determined based on the measured forefield area and either literature values of mean sediment thickness or direct depth measurements using electrical resistivity tomography. Methane was found in all sediments (0.08–73.81 µg CH4 g−1 dry weight) and most rocks (0.06–108.58 µg CH4 g−1) collected from the five glacier forefields, confirming that entrapped CH4 is ubiquitous in these calcareous formations. Geochemical analyses further confirmed a thermogenic origin of the entrapped CH4 (average δ13CCH4 of sediment of −28.23 (± 3.42) ‰; average gas-wetness ratio of 75.2 (± 48.4)). Whereas sediment-entrapped CH4 contents varied moderately within individual forefields, we noted a large, significant difference in the CH4 content and total CH4 mass (range of 200–3881 t CH4) between glacier forefields at the regional scale. The lithology and tectonic setting within the Helvetic nappes appeared to be dominant factors determining rock and sediment CH4 contents. Overall, a substantial quantity of CH4 was found to be entrapped in Swiss calcareous glacier forefields. Its potential release and subsequent fate in this environment is the subject of ongoing studies.

Description: Hydrogen cyanide (HCN) is considered a fundamental molecule in prebiotic chemistry experiments due to the fact that it could have an important role as raw material to form more complex molecules, as well as it could be an intermediate molecule in chemical reactions. However, the primitive scenarios in which this molecule might be available have been widely discussed. Hydrothermal systems have been considered as abiotic reactors and ideal niches for chemical evolution. Nevertheless, several experiments have shown that high temperatures and pressures could be adverse to the stability of organic molecules. Thus, it is necessary to carry out systematic experiments to study the synthesis, stability and fate of organic molecules in hydrothermal scenarios. In this work, we performed experiments focused on the stability and fate of HCN under a simple hydrothermal system scenario: the thermolysis of HCN at 100°C, at acidic and basic pH and in the presence of Mg-montmorillonite. Furthermore, we analysed the products from HCN thermolysis and highlighted the role of these chemical species as prebiotic molecules under a hydrothermal scenario.

Description: On 5 March 2019 12:00 UTC, an atmospheric river (AR) made landfall in Santa Barbara, CA, and lasted approximately 30 h. While ARs are typical winter storms in the area, the extraordinary number of lightning strikes observed near coastal Santa Barbara made this event unique. The Earth Networks Global Lightning Network (ENGLN) detected 8811 lightning flashes around southern California (30 to 37∘ N and 130 to 115∘ W) in 24 h, which is roughly 2500 times the climatological flash rate in this region. The AR-related thunderstorm resulted in approximately 23.18 mm accumulated precipitation in 30 h in Santa Barbara. This article examines synoptic and mesoscale features conducive to this electrifying AR event, characterizing its uniqueness in the context of previous March events that made landfall in the region. We show that this AR was characterized by an unusual deep moist layer extending from the low to mid-troposphere in an environment with potential instability and low-elevation freezing level. Despite the negligible convective available potential energy (CAPE) during the peak of the thunderstorm near Santa Barbara, the lifting of layers with high water vapor content in the AR via warm conveyor belt and orographic forcing in a convectively unstable atmosphere resulted in the formation of hail and enhanced electrification.

Description: The cross-sectional profile of a glacial valley can be obtained with a variational principle in which the friction against the valley walls and the glacier bed is extremized, subject to a Lagrangian constraint. We show that the actual valley profile maximizes the friction, thus settling an old debate.

Description: The objective of this study was to identify attitudes towards the scientific search for extraterrestrial life among students from public and private universities in Peru. This research was inspired by similar studies, realized in Sweden, which used the same instrument adapting it to our reality. The process consisted of a survey of the Peruvian student population by targeting it in different regions of Peru. The sample consisted of 1237 students from different academic areas. The findings show that 92% of the students believe in the existence of life outside our planet, with differences between the subgroups surveyed.

Description: Limited availability of ground measurements in the vast majority of river basins world-wide increases the value of alternative data sources such as satellite observations in hydrological modelling. This study investigates the potential of using remotely sensed river water levels, i.e. altimetry observations, from multiple satellite missions to identify parameter sets for a hydrological model in the semi-arid Luangwa River basin in Zambia. A distributed process-based rainfall–runoff model with sub-grid process heterogeneity was developed and run on a daily timescale for the time period 2002 to 2016. As a benchmark, feasible model parameter sets were identified using traditional model calibration with observed river discharge data. For the parameter identification using remote sensing, data from the Gravity Recovery and Climate Experiment (GRACE) were used in a first step to restrict the feasible parameter sets based on the seasonal fluctuations in total water storage. Next, three alternative ways of further restricting feasible model parameter sets using satellite altimetry time series from 18 different locations along the river were compared. In the calibrated benchmark case, daily river flows were reproduced relatively well with an optimum Nash–Sutcliffe efficiency of ENS,Q=0.78 (5/95th percentiles of all feasible solutions ENS,Q,5/95=0.61–0.75). When using only GRACE observations to restrict the parameter space, assuming no discharge observations are available, an optimum of ENS,Q=-1.4 (ENS,Q,5/95=-2.3–0.38) with respect to discharge was obtained. The direct use of altimetry-based river levels frequently led to overestimated flows and poorly identified feasible parameter sets (ENS,Q,5/95=-2.9–0.10). Similarly, converting modelled discharge into water levels using rating curves in the form of power relationships with two additional free calibration parameters per virtual station resulted in an overestimation of the discharge and poorly identified feasible parameter sets (ENS,Q,5/95=-2.6–0.25). However, accounting for river geometry proved to be highly effective. This included using river cross-section and gradient information extracted from global high-resolution terrain data available on Google Earth and applying the Strickler–Manning equation to convert modelled discharge into water levels. Many parameter sets identified with this method reproduced the hydrograph and multiple other signatures of discharge reasonably well, with an optimum of ENS,Q=0.60 (ENS,Q,5/95=-0.31–0.50). It was further shown that more accurate river cross-section data improved the water-level simulations, modelled rating curve, and discharge simulations during intermediate and low flows at the basin outlet where detailed on-site cross-section information was available. Also, increasing the number of virtual stations used for parameter selection in the calibration period considerably improved the model performance in a spatial split-sample validation. The results provide robust evidence that in the absence of directly observed discharge data for larger rivers in data-scarce regions, altimetry data from multiple virtual stations combined with GRACE observations have the potential to fill this gap when combined with readily available estimates of river geometry, thereby allowing a step towards more reliable hydrological modelling in poorly gauged or ungauged basins.

Description: Astrobiology has been gaining increasing scientific prominence and public attention as the search for life beyond Earth continues to make significant headway on multiple fronts. In view of these recent developments, the fascinating and dynamic etymology of astrobiology is elucidated, and thus shown to encompass a plethora of vivid characters drawn from different continents, religions, ideologies and centuries.

Description: The Maxwell elasto-brittle (MEB) rheology is implemented in the Eulerian finite-difference (FD) modeling framework commonly used in classical viscous-plastic (VP) models. The role of the damage parameterization, the cornerstone of the MEB rheology, in the formation and collapse of ice arches and ice bridges in a narrow channel is investigated. Ice bridge simulations are compared with observations to derive constraints on the mechanical properties of landfast sea ice. Results show that the overall dynamical behavior documented in previous MEB models is reproduced in the FD implementation, such as the localization of the damage in space and time and the propagation of ice fractures in space at very short timescales. In the simulations, an ice arch is easily formed downstream of the channel, sustaining an ice bridge upstream. The ice bridge collapses under a critical surface forcing that depends on the material cohesion. Typical ice arch conditions observed in the Arctic are best simulated using a material cohesion in the range of 5–10 kN m−2. Upstream of the channel, fracture lines along which convergence (ridging) takes place are oriented at an angle that depends on the angle of internal friction. Their orientation, however, deviates from the Mohr–Coulomb theory. The damage parameterization is found to cause instabilities at large compressive stresses, which prevents the production of longer-term simulations required for the formation of stable ice arches upstream of the channel between these lines of fracture. Based on these results, we propose that the stress correction scheme used in the damage parameterization be modified to remove numerical instabilities.

Description: Based on the discourse analysis of articles collected between 2010 and 2016 from the Süddeutsche Zeitung – a leading local and German national newspaper – my aim is to reconstruct the central conditions limiting or enabling the participation of those citizens in the public discourse who are generally constructed as „migrants“. Therefore, I analyse the central elements of the discourse around the subject migration/integration. My analysis is guided by the ‚postmigrant debate‘, in particular by the approaches of the ‚differential inclusion‘ of migrantised groups and their ‚struggles of migration‘ combining it with critical race debates. My aim is to outline the different discursive ways that allow migrantised citizens to participate in public meaning making, and the ways, they use to contest majoritarian views. My analysis reveals their critical reconsideration of the system of differentiated inclusion, which is organizing the majoritarian discourse and ‚migrants‘ everyday lives. While the journalistic strategy exemplified within the analysis is working in support of the ‚migrant's perspectives‘, it simultaneously acts to normalize majoritarian position contra migration.

Description: Cave microclimate and geochemical monitoring is vitally important for correct interpretations of proxy time series from speleothems with regard to past climatic and environmental dynamics. We present results of a comprehensive cave-monitoring programme in Waipuna Cave in the North Island of New Zealand, a region that is strongly influenced by the Southern Westerlies and the El Niño–Southern Oscillation (ENSO). This study aims to characterise the response of the Waipuna Cave hydrological system to atmospheric circulation dynamics in the southwestern Pacific region in order to assure the quality of ongoing palaeo-environmental reconstructions from this cave. Drip water from 10 drip sites was collected at roughly monthly intervals for a period of ca. 3 years for isotopic (δ18O, δD, d-excess parameter, δ17O, and 17Oexcess) and elemental (Mg∕Ca and Sr∕Ca) analysis. The monitoring included spot measurements of drip rates and cave air CO2 concentration. Cave air temperature and drip rates were also continuously recorded by automatic loggers. These datasets were compared to surface air temperature, rainfall, and potential evaporation from nearby meteorological stations to test the degree of signal transfer and expression of surface environmental conditions in Waipuna Cave hydrochemistry. Based on the drip response dynamics to rainfall and other characteristics, we identified three types of discharge associated with hydrological routing in Waipuna Cave: (i) type 1 – diffuse flow, (ii) type 2 – fracture flow, and (iii) type 3 – combined flow. Drip water isotopes do not reflect seasonal variability but show higher values during severe drought. Drip water δ18O values are characterised by small variability and reflect the mean isotopic signature of precipitation, testifying to rapid and thorough homogenisation in the epikarst. Mg∕Ca and Sr∕Ca ratios in drip waters are predominantly controlled by prior calcite precipitation (PCP). Prior calcite precipitation is strongest during austral summer (December–February), reflecting drier conditions and a lack of effective infiltration, and is weakest during the wet austral winter (July–September). The Sr∕Ca ratio is particularly sensitive to ENSO conditions due to the interplay of congruent or incongruent host rock dissolution, which manifests itself in lower Sr∕Ca in above-average warmer and wetter (La Niña-like) conditions. Our microclimatic observations at Waipuna Cave provide a valuable baseline for the rigorous interpretation of speleothem proxy records aiming at reconstructing the past expression of Pacific climate modes.

Description: Ensuring the highest quality standards at competitive prices is one of the greatest challenges in the manufacture of electronic products. The identification of flaws has the uppermost priority in the field of automotive electronics, particularly as a failure within this field can result in damages and fatalities. During assembling and soldering of printed circuit boards (PCBs) the circuit carriers can be subject to errors. Hence, automatic optical inspection (AOI) systems are used for real-time detection of visible flaws and defects in production. This article introduces an application strategy for combining a deep learning concept with an optical inspection system based on image processing. Above all, the target is to reduce the risk of error slip through a second inspection. The concept is to have the inspection results additionally evaluated by a convolutional neural network. For this purpose, different training datasets for the deep learning procedures are examined and their effects on the classification accuracy for defect identification are assessed. Furthermore, a suitable compilation of image datasets is elaborated, which ensures the best possible error identification on solder joints of electrical assemblies. With the help of the results, convolutional neural networks can achieve a good recognition performance, so that these can support the automatic optical inspection in a profitable manner. Further research aims at integrating the concept in a fully automated way into the production process in order to decide on the product quality autonomously without human interference.

Description: The dynamics of the physicochemical and biological parameters were followed during the decline of a Cymodocea nodosa meadow in the northern Adriatic Sea from July 2017 to October 2018. During the regular growth of C. nodosa from July 2017 to March 2018, the species successfully adapted to the changes in environmental conditions and prevented H2S accumulation by its reoxidation, supplying the sediment with O2 from the water column and/or leaf photosynthesis. The C. nodosa decline was most likely triggered in April 2018 when light availability to the plant was drastically reduced due to increased seawater turbidity that resulted from increased terrigenous input, indicated by a decrease in salinity accompanied with a substantial increase in particulate matter concentration, combined with resuspension of sediment and elevated autotrophic biomass. Light reduction impaired photosynthesis of C. nodosa and the oxidation capability of belowground tissue. Simultaneously, a depletion of oxygen due to intense oxidation of H2S occurred in the sediment, thus creating anoxic conditions in most of the rooted areas. These linked negative effects on the plant performance caused an accumulation of H2S in the sediments of the C. nodosa meadow. During the decay of aboveground and belowground tissues, culminating in August 2018, high concentrations of H2S were reached and accumulated in the sediment as well as in bottom waters. The influx of oxygenated waters in September 2018 led to the re-establishment of H2S oxidation in the sediment and remainder of the belowground tissue. Our results indicate that if disturbances of environmental conditions, particularly those compromising the light availability, take place during the recruitment phase of plant growth when metabolic needs are at a maximum and stored reserves minimal, a sudden and drastic decline of the seagrass meadow occurs.

Description: A number of seaside communities in Troms, northern Norway, are vulnerable to sudden weather-induced access disruptions due to high-impact weather and dependency on one or few roads. In this paper we study changes in winter weather known to potentially cause access disruptions in Troms, for the present climate (1958–2017) and two future periods (2041–2070; 2071–2100). We focus on climate indices associated with snow avalanches and weather that may lead to for example slippery road conditions. In two focus areas, the most important results show larger snow amounts now compared to 50 years ago, and heavy snowfall has become more intense and frequent. This trend is expected to turn in the future, particularly at low elevations where snow cover during winter might become a rarity by 2100. Strong snow drift, due to a combination of snowfall and wind speed, has slightly increased in the two focus areas, but a strong decrease is expected in the future due to less snow. Events of heavy rain during winter are rather infrequent in the present winter climate of Troms, but we show that these events are likely to occur much more often in all regions in the future.

Description: Quantifying the rate of wave attenuation in sea ice is key to understanding trends in the Antarctic marginal ice zone extent. However, a paucity of observations of waves in sea ice limits progress on this front. We deployed 14 waves-in-ice observation systems (WIIOS) on Antarctic sea ice during the Polynyas, Ice Production, and seasonal Evolution in the Ross Sea expedition (PIPERS) in 2017. The WIIOS provide in situ measurement of surface wave characteristics. Two experiments were conducted, one while the ship was inbound and one outbound. The sea ice throughout the experiments generally consisted of pancake and young ice

Description: The Antarctic ice sheet extent in the Weddell Sea embayment (WSE) during the Last Glacial Maximum (LGM; ca. 19–25 calibrated kiloyears before present, ka cal BP) and its subsequent retreat from the shelf are poorly constrained, with two conflicting scenarios being discussed. Today, the modern Brunt Ice Shelf, the last remaining ice shelf in the northeastern WSE, is only pinned at a single location and recent crevasse development may lead to its rapid disintegration in the near future. We investigated the seafloor morphology on the northeastern WSE shelf and discuss its implications, in combination with marine geological records, to create reconstructions of the past behaviour of this sector of the East Antarctic Ice Sheet (EAIS), including ice–seafloor interactions. Our data show that an ice stream flowed through Stancomb-Wills Trough and acted as the main conduit for EAIS drainage during the LGM in this sector. Post-LGM ice stream retreat occurred stepwise, with at least three documented grounding-line still-stands, and the trough had become free of grounded ice by ∼10.5 ka cal BP. In contrast, slow-flowing ice once covered the shelf in Brunt Basin and extended westwards toward McDonald Bank. During a later time period, only floating ice was present within Brunt Basin, but large “ice slabs” enclosed within the ice shelf occasionally ran aground at the eastern side of McDonald Bank, forming 10 unusual ramp-shaped seabed features. These ramps are the result of temporary ice shelf grounding events buttressing the ice further upstream. To the west of this area, Halley Trough very likely was free of grounded ice during the LGM, representing a potential refuge for benthic shelf fauna at this time.

Description: Expansion of the hydrologically connected area during rainfall events causes previously disconnected areas to contribute to streamflow. If these newly contributing areas have a different hydrochemical composition compared to the previously connected contributing areas, this may cause a change in stream water chemistry that cannot be explained by simple mixing of rainfall and baseflow. Changes in stormflow composition are, therefore, sometimes used to identify when transiently connected areas (or water sources) contribute to stormflow. We identified the dominant sources of streamflow for a steep 20 ha pre-Alpine headwater catchment in Switzerland and investigated the temporal changes in connectivity for four rainfall events based on stream water concentrations and groundwater level data. First, we compared the isotopic and chemical composition of stormflow at the catchment outlet to the composition of rainfall, groundwater and soil water. Three-component end-member mixing analyses indicated that groundwater dominated stormflow during all events, and that soil water fractions were minimal for three of the four events. However, the large variability in soil and groundwater composition compared to the temporal changes in stormflow composition inhibited the determination of the contributions from the different groundwater sources. Second, we estimated the concentrations of different solutes in stormflow based on the mixing fractions derived from two-component hydrograph separation using a conservative tracer (δ2H) and the measured concentrations of the solutes in baseflow and rainfall. The estimated concentrations differed from the measured stormflow concentrations for many solutes and samples. The deviations increased gradually with increasing streamflow for some solutes (e.g. iron and copper), suggesting increased contributions from riparian and hillslope groundwater with higher concentrations of these solutes and thus increased hydrological connectivity. The findings of this study show that solute concentrations partly reflect the gradual changes in hydrologic connectivity, and that it is important to quantify the variability in the composition of different source areas.

Description: Recent application of Fourier transform near infra-red spectroscopy (FT-NIRS) to predict age in fish otoliths has gained attention among fisheries managers as a potential alternative to costly production ageing of managed species. We assessed the age prediction capability of FT-NIRS scans in whole otoliths from red snapper, Lutjanus campechanus, collected from the US Gulf of Mexico and US Atlantic Ocean (South Atlantic). Otoliths were scanned with an FT-NIR spectrometer and resulting spectral signatures were regressed with traditionally estimated ages via partial least squares regression to produce calibration models, which were validated for predictive capability against test sets of otoliths. Calibration models successfully predicted age with R2 ranging 0.94–0.95, mean squared error ≤1.8 years, and bias 31 years were not well predicted, possibly due to light attenuation in the thickest otoliths. Our results suggest that FT-NIRS can improve efficiency in production ageing for fisheries management while maintaining data quality standards.

Description: This article investigates the diet of the snow crab (Chionoecetes opilio) and its feeding intensity in the Barents Sea. Data show that snow crab has a diverse diet that includes almost all types of benthic invertebrates living in the Barents Sea. There are differences between the diets of females and males and of juveniles and adults. Juveniles and females typically occupy shallow areas with communities of bivalve molluscs, while males typically live deeper on slopes and depressions where polychaetes and crustaceans are the most abundant groups. Stomach contents were analysed to determine the species composition and frequency of occurrence of various benthic taxa. Consumption of food was estimated and compared with data from the Russian seas of the Pacific region. The total annual consumption of macrozoobenthos by snow crab was calculated in accordance with its current distribution in the Barents Sea. Snow crab consumes at least 30 000 tonnes of benthos annually, which amounts to 0.1–0.2% of the total macrozoobenthic biomass in the investigated area. The population of snow crab causes the largest impact on the benthic communities in the northeastern part of the Barents Sea and near the south side of the Novaya Zemlya archipelago.

Description: In this study, the fine-scale responses of a stratified oligotrophic karstic lake (Kozjak Lake, Plitvice Lakes, Croatia; the lake fetch is 2.3 km, and the maximum depth is 46 m) to atmospheric forcing on the lake surface are investigated. Lake temperatures measured at a resolution of 2 min at 15 depths ranging from 0.2 to 43 m, which were observed during the 6 July–5 November 2018 period, were analyzed. The results show thermocline deepening from 10 m at the beginning of the observation period to 16 m at the end of the observation period, where the latter depth corresponds to approximately one-third of the lake depth. The pycnocline followed the same pattern, except that the deepening occurred throughout the entire period approximately 1 m above the thermocline. On average, thermocline deepening was 3–4 cm d−1, while the maximum deepening (12.5 cm d−1) coincided with the occurrence of internal seiches. Furthermore, the results indicate three different types of forcings on the lake surface; two of these forcings have diurnal periodicity – (1) continuous heat fluxes and (2) occasional periodic stronger winds – whereas forcing (3) corresponds to occasional nonperiodic stronger winds with steady along-basin directions. Continuous heat fluxes (1) produced forced diurnal oscillations in the lake temperature within the first 5 m of the lake throughout the entire observation period. Noncontinuous periodic stronger winds (2) resulted in occasional forced diurnal oscillations in the lake temperatures at depths from approximately 7 to 20 m. Occasional strong and steady along-basin winds (3) triggered both baroclinic internal seiches with a principal period of 8.0 h and barotropic surface seiches with a principal period of 9 min. Lake currents produced by the surface seiches under realistic-topography conditions generated baroclinic oscillations of the thermocline region (at depths from 9 to 17 m) with periods corresponding to the period of surface seiches (≈ 9 min), which, to the best of our knowledge, has not been reported in previous lake studies.

Description: Deglaciation of high mountain rockwalls alters slope stability as rockwalls become more sensitive to modifications in environmental factors (e.g. seasonal temperature variations). In the past decades, increasing efforts focused on studying deglaciated Alpine rockwalls. Yet, currently deglaciating rockfaces remain unstudied. Here, we quantify surface area variations of massive ice bodies lying on high mountain rockwalls (ice aprons) in the French sector of the Mont Blanc massif between the end of the Little Ice Age (LIA) and 2018. Surface area estimates are computed from terrestrial and aerial oblique photographs via photogrammetry. This technique allows using photographs taken without scientific intent, and to tap into diverse historical or recent photographic catalogs. We derive an ice apron surface area model from precipitation records and the positive degree-days. The studied ice aprons shrank from 1854 to the 1950s, before expanding until the end of the 1990s. The beginning of the 21st century shows a decrease in surface area, leading to the complete melt of one of the studied ice aprons in 2017. Observed variations correlate with modeled surface area, suggesting strong sensitivity of ice aprons to changes in climatic variables. By studying site-specific correlations, we explore the importance of local drivers over the balance of ice aprons.

Description: Until the late 19th century, extensive beds of flat oyster Ostrea edulis populated the Central North Sea, which have vanished after intensive fisheries. At present, various initiatives are being carried out to investigate the potential to restore this former key species in the area. This historical ecological study contributes by delineating the former oyster bed area and through an assessment of its limits against known gradients in the North Sea. Extensive data from historical maps, texts, and ship-based surveys were used to synthesize our knowledge on the former beds. It was revealed that the area with oyster beds covered ∼6.2% of the total North Sea bottom, with a delineation that could partly be explained by hydrodynamic and temperature gradients. The position and extent of the area are notably different from the area that is used in recent feasibility studies on the restoration of North Sea oyster beds. The offshore oysters lived on muddy sand in relatively cold conditions, and there are several indications that their reproductive rate was low. The apparent disappearance of cold water adapted flat oysters will challenge restoration projects. This study provides indispensable information for the future restoration of flat oyster beds in the North Sea.

Description: Many wetlands have been drained due to urbanization, agriculture, forestry or other purposes, which has resulted in a loss of their ecosystem services. To protect receiving waters and to achieve services such as flood control and storm water quality mitigation, new wetlands are created in urbanized areas. However, our knowledge of greenhouse gas exchange in newly created wetlands in urban areas is currently limited. In this paper we present measurements carried out at a created urban wetland in Southern Finland in the boreal climate. We conducted measurements of ecosystem CO2 flux and CH4 flux (FCH4) at the created storm water wetland Gateway in Nummela, Vihti, Southern Finland, using the eddy covariance (EC) technique. The measurements were commenced the fourth year after construction and lasted for 1 full year and two subsequent growing seasons. Besides ecosystem-scale fluxes measured by the EC tower, the diffusive CO2 and CH4 fluxes from the open-water areas (FwCO2 and FwCH4, respectively) were modelled based on measurements of CO2 and CH4 concentration in the water. Fluxes from the vegetated areas were estimated by applying a simple mixing model using the above-mentioned fluxes and the footprint-weighted fractional area. The half-hourly footprint-weighted contribution of diffusive fluxes from open water ranged from 0 % to 25.5 % in 2013. The annual net ecosystem exchange (NEE) of the studied wetland was 8.0 g C-CO2 m−2 yr−1, with the 95 % confidence interval between −18.9 and 34.9 g C-CO2 m−2 yr−1, and FCH4 was 3.9 g C-CH4 m−2 yr−1, with the 95 % confidence interval between 3.75 and 4.07 g C-CH4 m−2 yr−1. The ecosystem sequestered CO2 during summer months (June–August), while the rest of the year it was a CO2 source. CH4 displayed strong seasonal dynamics, higher in summer and lower in winter, with a sporadic emission episode in the end of May 2013. Both CH4 and CO2 fluxes, especially those obtained from vegetated areas, exhibited strong diurnal cycles during summer with synchronized peaks around noon. The annual FwCO2 was 297.5 g C-CO2 m−2 yr−1 and FwCH4 was 1.73 g C-CH4 m−2 yr−1. The peak diffusive CH4 flux was 137.6 nmol C-CH4 m−2 s−1, which was synchronized with the FCH4. Overall, during the monitored time period, the established storm water wetland had a climate-warming effect with 0.263 kg CO2-eq m−2 yr−1 of which 89 % was contributed by CH4. The radiative forcing of the open-water areas exceeded that of the vegetation areas (1.194 and 0.111 kg CO2-eq m−2 yr−1, respectively), which implies that, when considering solely the climate impact of a created wetland over a 100-year horizon, it would be more beneficial to design and establish wetlands with large patches of emergent vegetation and to limit the areas of open water to the minimum necessitated by other desired ecosystem services.

Description: This study focused on the ability of the Antarctic bacterium Rhodococcus sp. strain AQ5-14 to survive exposure to and to degrade high concentrations of phenol at 0.5 g l-1. After initial evaluation of phenol-degrading performance, the effects of salinity, pH and temperature on the rate of phenol degradation were examined. The optimum conditions for phenol degradation were pH 7 and 0.4 g l-1 NaCl at a temperature of 25°C (83.90%). An analysis using response surface methodology (RSM) and the Plackett-Burman design identified salinity, pH and temperature as three statistically significant factors influencing phenol degradation. The maximum bacterial growth was observed (optical density at 600 nm = 0.455), with medium conditions of pH 6.5, 22.5°C and 0.47 g l-1 NaCl in the central composite design of the RSM experiments enhancing phenol degradation to 99.10%. A central composite design was then used to examine the interactions among these three variables and to determine their optimal levels. There was excellent agreement (R2 = 0.9785) between experimental and predicted values, with less strong but still good agreement (R2 = 0.8376) between the predicted model values and those obtained experimentally under optimized conditions. Rhodococcus sp. strain AQ5-14 has excellent potential for the bioremediation of phenol.

Description: The article addresses old ‘west-east discourses’ and how they continue to develop in the high north, and, not least, in the Norwegian petroleum debate. Adopting a discourse analytical perspective the author shows how environmental safety is used as an argument in favour of Norway producing oil in the Barents Sea at the earliest possible moment. This is only feasible if a connection is made in the public mind between Russia and the environment. These views, it is argued, stem from ideas about Russia that gained currency after the demise of the Soviet Union. While they perhaps have less to do with Russia's petroleum industry and environmental performance today, they nevertheless have a strong impact on how challenges in the high north and Arctic region are perceived. And, perhaps even more importantly, they define freedom of action and available options. In this paper all references to government departments refer to those of Norway.

Description: The effectiveness of international environmental cooperation is a theoretical and methodological challenge that has captured the interest of scholars and students of international relations in the recent years. This article is an evaluation of international environmental cooperation in northwest Russia by applying an approach developed in the Institutional Dimensions of Global Environmental Change (IDGEC) research programme of the International Human Dimension Programme (IHDP). The IDGEC approach emphasises the importance of complex diagnostics of institutional environmental arrangements in terms of performance. The approach relates to the effects of international environmental cooperation in terms of sustainability, efficiency, fairness, and robustness. The article focuses on Russian and Nordic experiences of international environmental cooperation, and the assessment of performance has been done by the participants themselves. According to the results of interviews and questionnaires, the cooperation is considered institutionally effective and robust in general. However, views about the environmental effects vary. Some problems exist that are related to sustainability and fairness, but the most critical issue is the lack of domestic environmental capacity in Russia.

Description: The thermal conductivity and diffusivity of natural snow computed from Fourier-type analyses of annual snow temperature variations are shown to be strongly temperature dependent. The computed temperature coefficients of-0.007 and -0.012 deg-1 respectively, agree well with older laboratory experiments carried out on polycrystalline ice.

Description: The movement at a marginal location on the Ward Hunt Ice Shelf, northern Ellesmere Island, was determined by repeated survey measurements with theodolite and geodimeter. The purpose and duration of the field work, and reduction of the observational data are described, and the resulting mean ice velocity of 0.53 m year-1 is discussed. Strain-rates of a 1 km by 1 km deformation figure are determined. The parameters n and B of Glen’s power flow law are determined by using the equations given by Nye and Weertman. The results are compared with experimental data. Computed ice stresses show that the “ridge-and-trough" structure on the ice shelf surface is not originated by internal ice forces. The elevations of all survey markers have been determined from vertical-angle measurements, and the peculiarities of atmospheric refraction in near-surface layers are discussed.

Description: Values of δ18OSMOW measured on ice from 250 m depth at old “Byrd station”. Antarctica, averaged about A monotonie trend in values through the 16 cm long core piece suggested that part of an annual layer was represented. Snow accumulation in excess of 14.4 g cm-2 year-1 ca 1 700 years B.P. is indicated.

Description: Grain-boundary thickness in polycrystalline ice is a function of time (age), salinity, tempera-turf ·, and mode of sample preparation. It is directly proportional to the salinity of the ice and the number-average grain diameter (spheres) or edge-length (cubes). Practically the total salt content resides in the grain boundary for low salinity ice samples. The gram-boundary thickness S is also directly proportional to growth time of the grains raised to a power n(n = 0.25 to 0.3) and increases exponentially with absolute temperature for constant salinity and age. The energy of activation for growth increases with salinity. The results of the grain-boundary thickness calculations are useful for evaluating grain-boundary diffusion coefficients.

Description: The Regenerative Enclosed Life Support Module Simulator (REMS) was designed to simulate the conditions aboard the International Space Station (ISS). This unique terrestrial, encapsulated environment for humans and their associated organisms allowed investigations into the microbial communities within an enclosed habitat system, primarily with respect to diversity, phylogeny and the possible impact on human health. To assess time- and/or condition-dependent changes in microbial diversity within REMS, a total of 27 air samples were collected during three consecutive months. The microbial burden and diversity were elucidated using culture-dependent and culture-independent molecular methods. The results indicate that during controlled conditions the total microbial burden detected by culture-dependent techniques (below a detectable level to 102 cells m−3of air) and intracellular ATP assay was significantly low (102–103 cells m−3of air), but increased during the uncontrolled post-operation phase (∼104 cells m−3of air). Only Gram-positive and α-proteobacteria grew under tested culture conditions, with a predominant occurrence ofMethylobacterium radiotolerans, andSphingomonas yanoikuyae. Direct DNA extraction and 16S rDNA sequencing methodology revealed a broader diversity of microbes present in the REMS air (51 species). Unlike culture-dependent analysis, both Gram-positive and proteobacteria were equally represented, while members of a few proteobaterial groups dominated (Rhodopseudomonas,Sphingomonas,Acidovorax,Ralstonia,Acinetobacter,Pseudomonas, andPsychrobacter). Although the presence of several opportunistic pathogens warrants further investigation, the results demonstrated that routine maintenance such as controlling the humidity, crew’s daily cleaning, and air filtration were effective in reducing the microbial burden in the REMS.

Description: Results art, presented of spectral analyses of the surface and bedrock profiles along a flow line of the Wilkes ice cap and the surface along the Greenland E.G.I.G. profile. Although the bedrock appears irregular over all was velengths studied, the ice-cap surface is typically characterized by a smooth curve with small-scale surface undulations superimposed on it. The following relations of Budd (1969, 19701 are confirmed. The “damping factor" or ratio of the bedrock amplitude to the surface amplitude is a minimum for wavelengths λ about 3.3 times the ice thickness. The surface lags the bed in the direction of motion by λ/4. The magnitude of the minimum damping factor φm is typically least near the coast, and increases inland depending on the ice thickness Z, the velocity V, and the mean ice viscosity η (which is a function of stress and temperature) according to where p is the mean ice density and g is the gravitational acceleration. Thus the determination of the damping factors provides a valuable means of estimating the ice flow parameter η.

Description: Recent observations on Bjornbo Gletscher (lat. 71°., long. 25° W.), East Greenland, have revealed that it has several features characteristic of a surging glacier. One outstanding feature is the occurrence of drop-like ice masses in the lower part of the glacier which do not appear to belong to the main glacier. A detailed petrographic comparison between the morainic debris surrounding these drop-like ice masses and the rocks occurring in the upper part of the glacier has been made. The results indicate that these drop-like ice masses have been inserted into the main glacier. This drop-like form is explained as being due to ice transport from the side valleys, and this occurred over a short period of time during the movement (or surge) of the main glacier. Because of the highly variable rock types occurring in the respective accumulation zones, petrographic examinations of other moraines in the ablation zone have been used to trace them back to their respective firn fields.The main glacier and the tributary glaciers are today static. Bjørnbo Gletscher is therefore characterized by both static and moving phases, and its dynamics are the same as those of surging glaciers. The quiescent phase is estimated to have been about 100 years. The next surge will presumably occur around 1990,

Description: A new technique for precisely detecting chlorides in ice has been developed. It is based on a microchemical contact reaction which takes place when a thin surface layer of ice melts through a membrane filter previously soaked in a concentrated solution of silver nitrate and dried. The silver chloride thus formed is reduced to metallic silver under ultra-violet light. The results on natural hailstones and laboratory doped ice show that foreign molecules are mainly segregated along the grain boundaries rather than being captured in the ice lattice.The technique, which makes quantitative evaluations possible, appears promising in all experimental studies on natural ice (hailstones and sea ice) and on ice artificially grown in the laboratory (by accretion or by freezing of solutions).

Description: Surface deformations in the neighborhood of a crevasse field were measured over short (3 m) gage lengths in order to study flow conditions associated with crevasse formation. The results obtained were unusual in that they were inconsistent with large-scale results found by previous workers. It was concluded that the presence of small-scale surface effects, such as fractures, pot-holes and healed crevasses give rise to small-scale deformation fields with large spatial and temporal variations and that there is a lower limit of gage length below which deformation measurements pertinent to regional (low phenomena cannot be made. This lower limit is apparently an order of magnitude greater than the spacing of the features which give rise to localized effects.

Description: The hypothesis of the explosion of a number of planets and moons of our Solar System during its 4.6-billion-year history is in excellent accord with all known observational constraints, even without adjustable parameters orad hochelper hypotheses. Many of its boldest predictions have been fulfilled. In most instances, these predictions were judged highly unlikely by the current standard models. Moreover, in several cases, the entire exploded planet model was at risk of being falsified if the predictions failed. The successful predictions include: (1) satellites of asteroids; (2) satellites of comets; (3) salt water in meteorites; (4) ‘roll marks’ leading to boulders on asteroids; (5) the time and peak rate of the 1999 Leonid meteor storm; (6) explosion signatures for asteroids; (7) the strongly spiked energy parameter for new comets; (8) the distribution of black material on slowly rotating airless bodies; (9) splitting velocities of comets; (10) the asteroid-like nature ofDeep Impacttarget Comet Tempel 1; and (11) the presence of high-formation-temperature minerals in theStardustcomet dust sample return. In physics and astronomy, hypotheses are either falsified if their predictions fail, or proved to be of value if they succeed. By all existing evidence, the exploded planet hypothesis has proved far more useful than the half-dozen or so hypotheses it would replace. Among the many important corollaries are these. (a) Perhaps as many as six former planets of our Solar System have exploded over its 4.6-billion-year history. (b) In particular, Mars is not an original planet, but a former moon of an exploded planet. (c) As a major player in Solar System evolution, the exploded planet scenario must be considered as a likely propagation vehicle for the spread of biogenic organisms. We conclude with a brief mention of three possible planetary explosion mechanisms.

Description: The degree and nature of association between trace metals (Cu, Pb, Zn, Ni, Ag, & Cd) and cyanobacterial mats, phytoplankton and sediments has been assessed in the Lake Vanda region of the Wright Valley, Victoria Land. Trace metal:Fe ratios and SEM imaging confirmed that apparent trace metal enrichment in cyanobacterial mats, relative to the sediment beneath, was due to incorporation of fine (sub-micron) sediment particles in the muciligenous matrix of the mat. In suspended particulate material (SPM) filtered from the oxic water of Lake Vanda and the Onyx River, the degree of trace metal binding to the SPM did not appear to correlate with phytoplankton content. Instead a positive correlation was observed between Fe and trace metal content. The SPM at the top of the lake water column, where only the finest sediment remains suspended, had the highest trace metal concentrations. It is concluded that the trace metal content of cyanobacterial mats and phytoplankton samples is primarily due to incorporation of fine sediment particles of high surface area which therefore enhance trace metal adsorption capacity. This reinforces the existing hypothesis that trace metal solubility in this environment is primarily controlled by abiotic processes.