Arsenic Cycling in Hydrocarbon Plumes: Secondary Effects of Natural Attenuation          下载免费PDF全文

Isabelle M. Cozzarelli  Madeline E. Schreiber  Melinda L. Erickson  Brady A. Ziegler 《Ground water》2016,54(1):35-45

Monitored natural attenuation is widely applied as a remediation strategy at hydrocarbon spill sites. Natural attenuation relies on biodegradation of hydrocarbons coupled with reduction of electron acceptors, including solid phase ferric iron (Fe(III)). Because arsenic (As) adsorbs to Fe‐hydroxides, a potential secondary effect of natural attenuation of hydrocarbons coupled with Fe(III) reduction is a release of naturally occurring As to groundwater. At a crude‐oil‐contaminated aquifer near Bemidji, Minnesota, anaerobic biodegradation of hydrocarbons coupled to Fe(III) reduction has been well documented. We collected groundwater samples at the site annually from 2009 to 2013 to examine if As is released to groundwater and, if so, to document relationships between As and Fe inside and outside of the dissolved hydrocarbon plume. Arsenic concentrations in groundwater in the plume reached 230 µg/L, whereas groundwater outside the plume contained less than 5 µg/L As. Combined with previous data from the Bemidji site, our results suggest that (1) naturally occurring As is associated with Fe‐hydroxides present in the glacially derived aquifer sediments; (2) introduction of hydrocarbons results in reduction of Fe‐hydroxides, releasing As and Fe to groundwater; (3) at the leading edge of the plume, As and Fe are removed from groundwater and retained on sediments; and (4) downgradient from the plume, patterns of As and Fe in groundwater are similar to background. We develop a conceptual model of secondary As release due to natural attenuation of hydrocarbons that can be applied to other sites where an influx of biodegradable organic carbon promotes Fe(III) reduction.  相似文献   

Late Glacial and Holocene temperature changes at Egelsee,Switzerland, reconstructed using subfossil chironomids     

Isabelle Larocque-Tobler  Oliver Heiri  Michael Wehrli 《Journal of Paleolimnology》2010,43(4):649-666

A temperature reconstruction using chironomids was attempted at Egelsee, Switzerland, a site where pollen and macrofossil records showed a correspondence between vegetation and climatic changes inferred by other proxies in Europe. The general pattern of temperature changes inferred from chironomids during the Late Glacial [i.e. cold temperatures between ca. 16,500 and 14,800 cal BP, close to present-day temperature between 15,000 and 13,000 cal BP and colder temperatures during the Younger Dryas (YD)], and the major temperature changes of the Holocene (i.e. the Younger Dryas–Holocene transition and the Late Holocene cooling trend) at Egelsee, were mirrored in other European climate reconstructions using various proxies. However, the amplitude of temperature changes during the YD was smaller than reconstructed by other proxies at various sites, and the 8,200 years BP event was not apparent. These differences between records were probably due to the dominance of Corynocera ambigua, with percentages reaching 60% in parts of the Egelsee sequence. This taxon was not present in any of the 103 lakes used for the transfer function and its absence may have yielded less accurate inferences. Its presence in samples only associated with cold inferences at Egelsee suggests that this taxon is a cold indicator. However, it was also found in warm Danish lakes and the factors that determine the presence of C. ambigua remain unexplained. Most samples had a poor fit to temperature and instead, dissolved organic carbon seemed to be a factor influencing the chironomid assemblages during the Holocene. These results illustrate the need to better understand the ecology of chironomids and to disentangle the various factors that affect chironomid communities through time. Ultimately, such information will lead to more accurate temperature reconstructions.  相似文献   

Sediment Yield During Late Glacial and Holocene periods in the Lac Chambon Watershed,Massif Central,France     

Jean-Jacques Macaire  Gilles Bossuet  Alain Choquier  Constantin Cocirta  Patrick de Luca  Andr Dupis  Isabelle Gay  Eric Mathey  Pascal Guenet 《地球表面变化过程与地形》1997,22(5):473-489

A sediment budget for the Late Glacial and Holocene periods was calculated for the Lac Chambon watershed which is located in a formerly glaciated temperate crystalline mountain area. It appears that over 15 500 years: (1) 69 per cent of eroded particles have been displaced by gravity processes and then stored within the watershed, compared to 31 per cent that have been displaced by running water and evacuated outward; (2) the mean mechanical erosion due to gravity processes on the slopes amounted to 16·1 ±6 m and only developed on a quarter of the watershed surface, whereas the mean mechanical erosion due to running water amounted 1·24 ± 0·37 m and involved the whole watershed surface. The mean sediment yields due to gravity processes on slopes were 2300 ± 1360, 1770 ± 960 and 380 ± 100 m³ km⁻³ a⁻¹, respectively, for basalts, and basic and acidic trachyandesites. Values of sediment yield due to running water were 49±15, 120±36 and 79±24 m³ km⁻² a⁻¹, respectively, during the Bôlling–Allerôd, the Younger Dryas and the Pre-Boreal–Boreal periods. They were 56±17 and 166±50 m³ km⁻² a⁻¹ during the Sub-Atlantic period before and after 1360 a BP , respectively. These values reflect variations in the natural environment and the impact of human-induced deforestation. © 1997 by John Wiley & Sons, Ltd.  相似文献   

Biodegradation in contaminated aquifers: incorporating microbial/molecular methods   总被引：2，自引：0，他引：2  

Weiss JV  Cozzarelli IM 《Ground water》2008,46(2):305-322

In order to evaluate natural attenuation in contaminated aquifers, there has been a recent recognition that a multidisciplinary approach, incorporating microbial and molecular methods, is required. Observed decreases in contaminant mass and identified footprints of biogeochemical reactions are often used as evidence of intrinsic bioremediation, but characterizing the structure and function of the microbial populations at contaminated sites is needed. In this paper, we review the experimental approaches and microbial methods that are available as tools to evaluate the controls on microbially mediated degradation processes in contaminated aquifers. We discuss the emerging technologies used in biogeochemical studies and present a synthesis of recent studies that serve as models of integrating microbiological approaches with more traditional geochemical and hydrogeologic approaches in order to address important biogeochemical questions about contaminant fate.  相似文献   

Autecology of Limnomysis benedeni Czerniavsky, 1882 (Crustacea: Mysida) in Lake Constance, Southwestern Germany     

Ren Gergs  Almut J. Hanselmann  Isabelle Eisele  Karl-Otto Rothhaupt 《Limnologica》2008,38(2):139-146

The Ponto-Caspian mysid Limnomysis benedeni was first recorded in Lake Constance in summer 2006, and a stable population developed at the site of discovery. Although this mysid is common in the Rhine and Danube rivers, little is known about its ecology and impact in systems of invasion. We investigated the autecology of L. benedeni in habitat-choice and food experiments. In the habitat-choice experiments, highly structured habitats, i.e., stones covered with zebra mussels (Dreissena polymorpha), macrophytes, and especially stonewort, were strongly preferred. In food experiments, L. benedeni fed mostly on food sources with a small particle size, e.g., biofilm on leaf litter, biodeposited material of zebra mussels, epilithon, and phytoplankton. We also compared the L. benedeni population data from Lake Constance with that from rivers. In Lake Constance, female L. benedeni were nearly 30% larger and carried more than three times more eggs in spring (9.4±0.6 mm and 28.4±5.7 eggs) than in summer (6.7±0.8 mm and 8.7±2.9 eggs). The mysids present in spring might be the generation that over-wintered; in summer, this generation was probably replaced by a new generation of smaller individuals. The large brood size and the detritivorous feeding strategy might allow L. benedeni to colonize Lake Constance rapidly.  相似文献   

Paleogeography of Lake Agassiz and regional post-glacial uplift history of the Flin Flon region, central Manitoba and Saskatchewan     

Isabelle McMartin 《Journal of Paleolimnology》2000,24(3):293-315

Detailed mapping and elevation measurements of glacial lake shorelines in the Flin Flon region has permitted the reconstruction of 6 well-defined levels of Lake Agassiz formed around 8.3 ka to 7.9 ka ¹⁴C BP. The Stonewall, The Pas, Gimli, Grand Rapids, Drunken Point and Ponton paleo-water planes have been tilted upward to the northeast in the Holocene, with gradients decreasing, from the highest to the lowest level, from about 0.34 m km^-1 to 0.22 m km^-1 in the study area. The Setting level, lower than the Ponton but less well defined, is also documented here for the first time. This mapping conclusively refutes the view, entrenched in the literature from the 1890's to the 1960's, that there has been negligible differential uplift in the region following final drainage of Lake Agassiz. The finding has major consequences regarding correlation of glacial lakes across the mid-continent, the post-glacial history of large lakes in the region, and for interpretation of earth rheology and its implications for ice sheet reconstruction.  相似文献   

Characterization of site conditions (soil class,V<Subscript>S30</Subscript>, velocity profiles) for 33 stations from the French permanent accelerometric network (RAP) using surface-wave methods     

Fabrice Hollender  Cécile Cornou  Aline Dechamp  Kaveh Oghalaei  Florence Renalier  Emeline Maufroy  Clément Burnouf  Sylvette Thomassin  Marc Wathelet  Pierre-Yves Bard  Vincent Boutin  Clément Desbordes  Isabelle Douste-Bacqué  Laetitia Foundotos  Cédric Guyonnet-Benaize  Vincent Perron  Julie Régnier  Agathe Roullé  Mickael Langlais  Deborah Sicilia 《Bulletin of Earthquake Engineering》2018,16(6):2337-2365

Data provided by accelerometric networks are important for seismic hazard assessment. The correct use of accelerometric signals is conditioned by the station site metadata quality (i.e., soil class, V_S30, velocity profiles, and other relevant information that can help to quantify site effects). In France, the permanent accelerometric network consists of about 150 stations. Thirty-three of these stations in the southern half of France have been characterized, using surface-wave-based methods that allow derivation of velocity profiles from dispersion curves of surface waves. The computation of dispersion curves and their subsequent inversion in terms of shear-wave velocity profiles has allowed estimation of V_S30 values and designation of soil classes, which include the corresponding uncertainties. From a methodological point of view, this survey leads to the following recommendations: (1) perform both active (multi-analysis surface waves) and passive (ambient vibration arrays) measurements to derive dispersion curves in a broadband frequency range; (2) perform active acquisitions for both vertical (Rayleigh wave) and horizontal (Love wave) polarities. Even when the logistic contexts are sometimes difficult, the use of surface-wave-based methods is suitable for station-site characterization, even on rock sites. In comparison with previous studies that have mainly estimated V_S30 indirectly, the new values here are globally lower, but the EC8-A class sites remain numerous. However, even on rock sites, high frequency amplifications may affect accelerometric records, due to the shallow relatively softer layers.  相似文献   

Urban hydrologic trend analysis based on rainfall and runoff data analysis and conceptual model calibration          下载免费PDF全文

Siao Sun  Sylvie Barraud  Flora Branger  Isabelle Braud  Hélène Castebrunet 《水文研究》2017,31(6):1349-1359

Urban stormwater is a major cause of urban flooding and natural water pollution. It is therefore important to assess any hydrologic trends in urban catchments for stormwater management and planning. This study addresses urban hydrological trend analysis by examining trends in variables that characterize hydrological processes. The original and modified Mann‐Kendall methods are applied to trend detection in two French catchments, that is, Chassieu and La Lechere, based on approximately 1 decade of data from local monitoring programs. In both catchments, no trend is found in the major hydrological process driver (i.e., rainfall variables), whereas increasing trends are detected in runoff flow rates. As a consequence, the runoff coefficients tend to increase during the study period, probably due to growing imperviousness with the local urbanization process. In addition, conceptual urban rainfall‐runoff model parameters, which are identified via model calibration with an event based approach, are examined. Trend detection results indicate that there is no trend in the time of concentration in Chassieu, whereas a decreasing trend is present in La Lechere, which, however, needs to be validated with additional data. Sensitivity analysis indicates that the original Mann‐Kendall method is not sensitive to a few noisy values in the data series.  相似文献   

Quaternary thermokarst and thermal erosion features in northern France: origin and palaeoenvironments     

Brigitte Van Vliet‐Lanoë  Jacques Brulhet  Philippe Combes  Cédric Duvail  Frédéric Ego  Stéphane Baize  Isabelle Cojan 《Boreas: An International Journal of Quaternary Research》2017,46(3):442-461

A thermokarst is a collapse feature resulting from the thawing of ice‐rich permafrost or of massive ice of various origins. Little attention has been paid to the sedimentary fabric resulting from this type of collapse, except for glaciotectonic features. In western Europe, two palaeo‐forms are commonly studied: lithalsas and ice‐wedge casts. Collapsed pingos are much rarer. Very few papers have compiled present‐day and fossil data. Here, field data collected from quarries in the eastern Paris Basin were analysed, providing useful records of thermokarst collapses in alluvial calcareous silts, sands, and gravels. These forms have a circular shape when viewed on satellite images. Permafrost is attested regionally by the recurrent occurrence of meter‐sized pattern grounds at the surface of the chalk and of ice‐wedge casts. Traces of segregation and reticulate ice are common. These features are primarily connected to a major interstadial, c. 150 ka BP, orbitally forced and commonly associated with a major glacial retreat. They occur both in drained and waterlogged situations, resulting in a specific pattern of deformation. They are controlled by the brittle and plastic behaviour of sediments and resemble passive glaciotectonism. Normal and reverse faults, with the offset decreasing downward, are common, and those with local shear are reported. Lithalsas, seasonal frost blisters, spring frost blisters and perhaps pingos seem to have formed. Most of these deformations correspond to thermokarst sinkholes bordered by gravitational collapse faults. The offset of these faults increases towards the surface, and the faults have been recurrently confused with neotectonism triggered by palaeo‐earthquakes. However, there are no faults beneath the observed deformation features, and the region lacks recorded seismic activity over the last century. Our data may be helpful in interpreting similar structures elsewhere.  相似文献   

Information content of snow hydrological signatures based on streamflow,precipitation and air temperature     

Ivan Horner  Flora Branger  Hilary McMillan  Olivier Vannier  Isabelle Braud 《水文研究》2020,34(12):2763-2779

Hydrological signatures that represent snow processes are valuable to gain insights into snow accumulation and snow melt dynamics. We investigated five snow signatures. Considering inter-annual average of each calendar day, two slopes derived from the relation between streamflow and air temperature for different periods and streamflow peak maxima are used as signatures. In addition, two different approaches are used to compute inter-annual average and yearly snow storage estimates. We evaluated the ability of these signatures to characterize average (a) snow melt dynamics and (b) snow storage. They were applied in 10 Critical Zone Observatory catchments of the Southern Sierra mountains (USA) characterized by a Mediterranean climate. The relevance and information content of the signatures are evaluated using snow depth and snow water equivalent measurements as well as inter-catchment differences in elevation. The slopes quantifying the relations between streamflow and air temperature and the date of streamflow peak were found to characterize snow melt dynamics in terms of snow melt rates and snow melt affected areas. Streamflow peak dates were linked to the period of highest snow melt rates. Snow storage could be estimated both on average, considering all years, and for each year. Snow accumulation dynamics could not be characterized due to the lack of streamflow response during the snow accumulation period. The signatures were found potentially valuable to gain insights into catchment scale snow processes. In particular, when comparing catchments or observed and simulated data, they could provide insights into differences in terms of (a) snow melt rate and/or snow melt affected area over the snow melt season and (b) average or yearly snow storage. Requiring only widely available data, these hydrological signatures can be valuable for snow processes characterization, catchment comparison/classification or model development, calibration or evaluation.  相似文献