Arsenic mobility in alteration products of sulfide-rich, arsenopyrite-bearing mine wastes, Snow Lake, Manitoba, Canada   总被引：2，自引：0，他引：2  

Kristin A. Salzsauler  Nikolay V. Sidenko  Barbara L. Sherriff 《Applied Geochemistry》2005,20(12):2303-2314

The Arsenopyrite Residue Stockpile (ARS) in Snow Lake, Manitoba contains approximately 250,000 tons of cyanide treated, refractory arsenopyrite ore concentrate. The residue was deposited between 1950 and 1959 in an open waste rock impoundment, and remained exposed until 2000, when the pile was capped with layers of waste rock and clay. During the time when the ARS was exposed to the atmosphere, arsenopyrite, pyrrhotite, pyrite and chalcopyrite were oxidized producing scorodite, jarosite and two generations of amorphous Fe sulfo-arsenates (AISA). These secondary phases attenuated some of the As released to pore water during oxidation in the upper layers of the ARS. The imposition of the cap prevented further oxidation. The secondary As minerals are not stable in the reduced environment that currently dominates the pile. Therefore, As currently is being released into the groundwater. Water in an adjacent monitoring well has concentrations of >20 mg/L total As with relative predominance of As(III).  相似文献   

Obsidian from the northern sector of the Main Ethiopian Rift: implications for archeology     

Agazi Negash  Mulugeta Alene  Asfawossen Asrat  Barbara Nash 《第四纪科学杂志》2021,36(4):664-671

Obsidian is abundant in the Main Ethiopian Rift (MER). Petrological and geochemical features of obsidian from four volcanic centers in the MER, namely Birenti, Dofen, Fentale and Kone, are presented. Compositional and petrological variability is noted among the Dofen and Fentale obsidian, but not in those from Kone and Birenti where each have separate but uniform elemental composition. The Fentale and Kone obsidian were source materials for the artifacts of a number of Middle Stone Age and Later Stone Age/Neolithic sites in the region. We have yet to determine whether Dofen and Birenti were sources for archeological artifacts. The study also shows that volcanic episodes from a single center do not necessarily result in compositional variability.  相似文献   

Impacts of a large Sahelian city on groundwater hydrodynamics and quality: example of Niamey (Niger)     

Aïssata B. Hassane  Christian Leduc  Guillaume Favreau  Barbara A. Bekins  Thomas Margueron 《Hydrogeology Journal》2016,24(2):407-423

The management of groundwater resources is very important in the semiarid Sahel region, which is experiencing rapid urban development. Impacts of urbanization on groundwater resources were investigated in the unconfined aquifer of the Continental Terminal beneath the city of Niamey, Niger, using water level and chemical data. Hydrodynamic and chemical changes are best described by a combination of factors including the historical development of the city, current land use, water-table depth and topography. Seasonal groundwater recharge occurs with high spatial variability, as indicated by water-level monitoring in all wells, but there was no interannual trend over the 5-year study period. Groundwater salinity shows high spatial variability and a minor rising trend. The highest salinity is in the old city centre, with Na–NO₃ dominant, and it increases seasonally with recharge. Salinity is much lower and more variable in the suburbs (Ca–HCO₃, Ca–NO₃, and Na–NO₃ dominant). Nitrate is the main ionic contaminant and is seasonally or permanently above the international guidelines for drinking water quality in 36 % of sampled wells, with a peak value of 112 mg L^?1 NO₃–N (8 meq L^?1). Comparison of urban and rural sites indicates a long-term increase in groundwater recharge and nitrate enrichment in the urban area with serious implications for groundwater management in the region.  相似文献   

Isotopic signatures for the assessment of snow water resources in the Moroccan high Atlas mountains: contribution to surface and groundwater recharge     

Angoran Baudelaire N’da  Lhoussaine Bouchaou  Barbara Reichert  Lahoucine Hanich  Yassine Ait Brahim  Abdelghani Chehbouni  El Hassane Beraaouz  Jean-Luc Michelot 《Environmental Earth Sciences》2016,75(9):755

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Changes in phosphorus content,phosphatase activity and some physicochemical and microbiological parameters of soil within the range of impact of illegal dumping sites in Bydgoszcz (Poland)     

Joanna Lemanowicz  Agata Bartkowiak  Barbara Breza-Boruta 《Environmental Earth Sciences》2016,75(6):510

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Assessment of the content of heavy metals and potential pathogenic microorganisms in soil under illegal dumping sites     

Agata Bartkowiak  Barbara Breza-Boruta  Joanna Lemanowicz 《Environmental Earth Sciences》2016,75(21):1401

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Potential Salinity and Temperature Futures for the Chesapeake Bay Using a Statistical Downscaling Spatial Disaggregation Framework     

Barbara A. Muhling  Carlos F. Gaitán  Charles A. Stock  Vincent S. Saba  Desiree Tommasi  Keith W. Dixon 《Estuaries and Coasts》2018,41(2):349-372

Estuaries are productive and ecologically important ecosystems, incorporating environmental drivers from watersheds, rivers, and the coastal ocean. Climate change has potential to modify the physical properties of estuaries, with impacts on resident organisms. However, projections from general circulation models (GCMs) are generally too coarse to resolve important estuarine processes. Here, we statistically downscaled near-surface air temperature and precipitation projections to the scale of the Chesapeake Bay watershed and estuary. These variables were linked to Susquehanna River streamflow using a water balance model and finally to spatially resolved Chesapeake Bay surface temperature and salinity using statistical model trees. The low computational cost of this approach allowed rapid assessment of projected changes from four GCMs spanning a range of potential futures under a high CO₂ emission scenario, for four different downscaling methods. Choice of GCM contributed strongly to the spread in projections, but choice of downscaling method was also influential in the warmest models. Models projected a ~2–5.5 °C increase in surface water temperatures in the Chesapeake Bay by the end of the century. Projections of salinity were more uncertain and spatially complex. Models showing increases in winter-spring streamflow generated freshening in the Upper Bay and tributaries, while models with decreased streamflow produced salinity increases. Changes to the Chesapeake Bay environment have implications for fish and invertebrate habitats, as well as migration, spawning phenology, recruitment, and occurrence of pathogens. Our results underline a potentially expanded role of statistical downscaling to complement dynamical approaches in assessing climate change impacts in dynamically challenging estuaries.  相似文献   

Community-based responses to climate hazards: typology and global analysis     

Paterson  Barbara  Charles  Anthony 《Climatic change》2019,152(3-4):327-343

Climatic Change - The severity and frequency of climate change hazards are increasing around the world. Because the impacts are most acutely felt in local communities, it is critical to improve...  相似文献   

Variation in style of magmatism and emplacement mechanism induced by changes in basin environments and stress fields (Pannonian Basin,Central Europe)     

Attila Petrik  Lszl Fodor  Lszl Bereczki  Zsombor Klembala  Rka Lukcs  Viktria Baranyi  Barbara Beke  Szabolcs Harangi 《Basin Research》2019,31(2):380-404

The development of high‐resolution 3D seismic cubes has permitted recognition of variable subvolcanic features mostly located in passive continental margins. Our study area is situated in a different tectonic setting, in the extensional Pannonian Basin system (central Europe) where the lithospheric extension was associated with a wide variety of magmatic suites during the Miocene. Our primary objective is to map the buried magmatic bodies, to better understand the temporal and spatial variation in the style of magmatism and emplacement mechanism within the first order Mid‐Hungarian Fault Zone (MHFZ) along which the substantial Miocene displacement took place. The combination of seismic, borehole and log data interpretation enabled us to delineate various previously unknown subvolcanic‐volcanic features. In addition, a new approach of neural network analysis on log data was applied to detect and quantitatively characterise hydrothermal mounds that are hard to interpret solely from seismic data. The volcanic activity started in the Middle Miocene and induced the development of extrusive volcanic mounds south of the NE‐SW trending, continuous strike‐slip fault zone (Hajdú Fault Zone). In the earliest Late Miocene (11.6–9.78 Ma), the style of magmatic activity changed resulting in emplacement of intrusions and development of hydrothermal mounds. Sill emplacement occurred from south‐east to north‐west based on primary flow‐emplacement structures. The time of sill emplacement and the development of hydrothermal mounds can be bracketed by onlapped forced folds and mounds. This time coincided with the acceleration of sedimentation producing poorly consolidated, water‐saturated sediments preventing magma from flowing to the paleosurface. The change in extensional direction resulted in change in fault pattern, thus the formerly continuous basin‐bounding strike‐slip fault became segmented which could facilitate the magma flow toward the basin centre.  相似文献   

Relict sand dredging for beach nourishment in the central Tyrrhenian Sea (Italy): effects on benthic assemblages     

Barbara La Porta  Monica Targusi  Loretta Lattanzi  Paola La Valle  Daniela Paganelli  & Luisa Nicoletti 《Marine Ecology》2009,30(S1):97-104

The aim of this study is to analyse the effects in space and time of relict sand-dredging activities on macrobenthic assemblages, in an area situated offshore Montalto di Castro (central Tyrrhenian Sea, Italy), and to analyse the recolonisation processes of macrobenthos in the dredged areas. The area in question is characterised by relict sand deposits (Holocenic paleo-beaches), used for beach nourishment along the Latium coast. The effects of sand extraction on benthic assemblages were investigated before, during and after three dredging operations. The sites analysed are located within the dredged areas (inside stations) and in neighbouring, not dredged, areas (outside stations). The results showed that the impact of sand extraction was confined to the dredged stations and to the areas in proximity to the dredged areas. During dredging activities, the structure of benthic assemblages within the impacted stations was characterised by low species richness and diversity. Both the direct removal of sediment and the re-suspension and consequent deposition of fine sediment affected benthic assemblages of the impacted stations. A few months after the dredgings, a recolonisation process was still observed at all the impacted stations. A gradual recolonisation process was observed at those stations affected by only one dredging, whereas a different recolonisation was observed at those stations affected by two dredgings over time. This study suggests that differences of re-colonisation processes of benthic assemblages are related to the intensity of dredging operations in terms of dredging frequency.  相似文献