The Experts below are selected from a list of 341445 Experts worldwide ranked by ideXlab platform
Jinwook Chung - One of the best experts on this subject based on the ideXlab platform.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H(2)-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California's San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l(-1) and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l(-1). Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 microg-ClO(4) l(-1). As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 microg-As l(-1). DBCP, present in one Groundwater at 1.4 microg l(-1), was reduced to below its detection limit of 0.01 microg l(-1), which is well below California's 0.2 microg l(-1) MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se degrees or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H(2)-based MBfR can reduce multiple oxidized contaminants simultaneously.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H2-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California’s San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l−1 and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l−1. Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 µg-ClO4 l−1. As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 µg-As l−1. DBCP, present in one Groundwater at 1.4 µg l−1, was reduced to below its detection limit of 0.01 µg l−1, which is well below California’s 0.2 µg l−1 MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se° or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H2-based MBfR can reduce multiple oxidized contaminants simultaneously.
Reid H Bowman - One of the best experts on this subject based on the ideXlab platform.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H(2)-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California's San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l(-1) and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l(-1). Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 microg-ClO(4) l(-1). As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 microg-As l(-1). DBCP, present in one Groundwater at 1.4 microg l(-1), was reduced to below its detection limit of 0.01 microg l(-1), which is well below California's 0.2 microg l(-1) MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se degrees or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H(2)-based MBfR can reduce multiple oxidized contaminants simultaneously.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H2-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California’s San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l−1 and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l−1. Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 µg-ClO4 l−1. As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 µg-As l−1. DBCP, present in one Groundwater at 1.4 µg l−1, was reduced to below its detection limit of 0.01 µg l−1, which is well below California’s 0.2 µg l−1 MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se° or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H2-based MBfR can reduce multiple oxidized contaminants simultaneously.
Bruce E Rittmann - One of the best experts on this subject based on the ideXlab platform.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H(2)-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California's San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l(-1) and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l(-1). Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 microg-ClO(4) l(-1). As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 microg-As l(-1). DBCP, present in one Groundwater at 1.4 microg l(-1), was reduced to below its detection limit of 0.01 microg l(-1), which is well below California's 0.2 microg l(-1) MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se degrees or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H(2)-based MBfR can reduce multiple oxidized contaminants simultaneously.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H2-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California’s San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l−1 and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l−1. Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 µg-ClO4 l−1. As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 µg-As l−1. DBCP, present in one Groundwater at 1.4 µg l−1, was reduced to below its detection limit of 0.01 µg l−1, which is well below California’s 0.2 µg l−1 MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se° or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H2-based MBfR can reduce multiple oxidized contaminants simultaneously.
David A Polya - One of the best experts on this subject based on the ideXlab platform.
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delineating sources of Groundwater recharge in an arsenic affected holocene aquifer in cambodia using stable isotope based mixing models
Journal of Hydrology, 2018Co-Authors: Laura A Richards, A J Boyce, C J Ballentine, Daniel Magnone, Maria J Casanuevamarenco, Bart E Van Dongen, David A PolyaAbstract:Chronic exposure to arsenic (As) through the consumption of contaminated Groundwaters is a major threat to public health in South and Southeast Asia. The source of As-affected Groundwaters is important to the fundamental understanding of the controls on As mobilization and subsequent transport throughout shallow aquifers. Using the stable isotopes of hydrogen and oxygen, the source of Groundwater and the interactions between various water bodies were investigated in Cambodia’s Kandal Province, an area which is heavily affected by As and typical of many circum-Himalayan shallow aquifers. Two-point mixing models based on δD and δ18O allowed the relative extent of evaporation of Groundwater sources to be estimated and allowed various water bodies to be broadly distinguished within the aquifer system. Model limitations are discussed, including the spatial and temporal variation in end member compositions. The conservative tracer Cl/Br is used to further discriminate between Groundwater bodies. The stable isotopic signatures of Groundwaters containing high As and/or high dissolved organic carbon plot both near the local meteoric water line and near more evaporative lines. The varying degrees of evaporation of high As Groundwater sources are indicative of differing recharge contributions (and thus indirectly inferred associated organic matter contributions). The presence of high As Groundwaters with recharge derived from both local precipitation and relatively evaporated surface water sources, such as ponds or flooded wetlands, are consistent with (but do not provide direct evidence for) models of a potential dual role of surface-derived and sedimentary organic matter in As mobilization.
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tracing organic matter composition and distribution and its role on arsenic release in shallow cambodian Groundwaters
Geochimica et Cosmochimica Acta, 2016Co-Authors: Michael Lawson, David A Polya, A J Boyce, Charlotte Bryant, C J BallentineAbstract:Biogeochemical processes that utilize dissolved organic carbon are widely thought to be responsible for the liberation of arsenic from sediments to shallow Groundwater in south and southeast Asia. The accumulation of this known carcinogen to hazardously high concentrations has occurred in the primary source of drinking water in large parts of densely populated countries in this region. Both surface and sedimentary sources of organic matter have been suggested to contribute dissolved organic carbon in these aquifers. However, identification of the source of organic carbon responsible for driving arsenic release remains enigmatic and even controversial. Here, we provide the most extensive interrogation to date of the isotopic signature of ground and surface waters at a known arsenic hotspot in Cambodia. We present tritium and radiocarbon data that demonstrates that recharge through ponds and/or clay windows can transport young, surface derived organic matter into Groundwater to depths of 44 m under natural flow conditions. Young organic matter dominates the dissolved organic carbon pool in Groundwater that is in close proximity to these surface water sources and we suggest this is likely a regional relationship. In locations distal to surface water contact, dissolved organic carbon represents a mixture of both young surface and older sedimentary derived organic matter. Ground–surface water interaction therefore strongly influences the average dissolved organic carbon age and how this is distributed spatially across the field site. Arsenic mobilization rates appear to be controlled by the age of dissolved organic matter present in these Groundwaters. Arsenic concentrations in shallow Groundwaters ( 20 m) Groundwaters. We suggest that, while the rate of arsenic release is greatest in shallow aquifer sediments, arsenic release also occurs in deeper aquifer sediments and as such remains an important process in controlling the spatial distribution of arsenic in the Groundwaters of SE Asia. Our findings suggest that any anthropogenic activities that alter the source of Groundwater recharge or the timescales over which recharge takes place may also drive changes in the natural composition of dissolved organic carbon in these Groundwaters. Such changes have the potential to influence both the spatial and temporal evolution of the current Groundwater arsenic hazard in this region.
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pond derived organic carbon driving changes in arsenic hazard found in asian Groundwaters
Environmental Science & Technology, 2013Co-Authors: Michael Lawson, David A Polya, A J Boyce, Charlotte Bryant, Debapriya Mondal, Andrew Shantz, C J BallentineAbstract:Microbially mediated reductive processes involving the oxidation of labile organic carbon are widely considered to be critical to the release of arsenic into shallow Groundwaters in South and Southeast Asia. In areas where there is significant pumping of Groundwater for irrigation the involvement of surface-derived organic carbon drawn down from ponds into the underlying aquifers has been proposed but remains highly controversial. Here we present isotopic data from two sites with contrasting Groundwater pumping histories that unequivocally demonstrate the ingress of surface pond-derived organic carbon into arsenic-containing Groundwaters. We show that pond-derived organic carbon is transported to depths of up to 50 m even in an arsenic-contaminated aquifer in Cambodia thought to be minimally disturbed by Groundwater pumping. In contrast, in the extensively exploited Groundwaters of West Bengal, we show that pond-derived organic carbon is transported in shallow Groundwater to greater depths, in excess of 100 m in the aquifer. Intensive pumping of Groundwaters may potentially drive secular increases in the Groundwater arsenic hazard in this region by increasing the contribution of bioavailable pond-derived dissolved organic carbon drawn into these aquifer systems and transporting it to greater depths than would operate under natural flow conditions.
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Arsenic hazard in shallow Cambodian Groundwaters
Mineralogical Magazine, 2005Co-Authors: David A Polya, A. G. Gault, N. Diebe, P. Feldman, J. W. Rosenboom, E. Gilligan, D. Fredericks, Abul Hasnat Milton, Mickey L. Sampson, H. A L RowlandAbstract:Our recent discovery of hazardous concentrations of arsenic in shallow sedimentary aquifers in Cambodia raises the spectre of future deleterious health impacts on a population that, particularly in non-urban areas, extensively use untreated Groundwater as a source of drinking water and, in some instances, as irrigation water. We present here small-scale hazard maps for arsenic in shallow Cambodian Groundwaters based on >1000 Groundwater samples analysed in the Manchester Analytical Geochemistry Unit and elsewhere. Key indicators for hazardous concentrations of arsenic in Cambodian Groundwaters include: (1) well depths greater than 16 m; (2) Holocene host sediments; and (3) proximity to major modern channels of the Mekong (and its distributary the Bassac). However, high-arsenic well waters are also commonly found in wells not exhibiting these key characteristics, notably in some shallower Holocene wells, and in wells drilled into older Quaternary and Neogene sediments. It is emphasized that the maps and tables presented are most useful for identifying current regional trends in Groundwater arsenic hazard and that their use for predicting arsenic concentrations in individual wells, for example for the purposes of well switching, is not recommended, particularly because of the lack of sufficient data (especially at depths >80 m) and because, as in Bangladesh and West Bengal, there is considerable heterogeneity of Groundwater arsenic concentrations on a scale of metres to hundreds of metres. We have insufficient data at this time to determine unequivocally whether or not arsenic concentrations are increasing in shallow Cambodian Groundwaters as a result of Groundwater-abstraction activities.
William F Wright - One of the best experts on this subject based on the ideXlab platform.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H(2)-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California's San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l(-1) and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l(-1). Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 microg-ClO(4) l(-1). As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 microg-As l(-1). DBCP, present in one Groundwater at 1.4 microg l(-1), was reduced to below its detection limit of 0.01 microg l(-1), which is well below California's 0.2 microg l(-1) MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se degrees or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H(2)-based MBfR can reduce multiple oxidized contaminants simultaneously.
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simultaneous bio reduction of nitrate perchlorate selenate chromate arsenate and dibromochloropropane using a hydrogen based membrane biofilm reactor
Biodegradation, 2007Co-Authors: Jinwook Chung, Bruce E Rittmann, William F Wright, Reid H BowmanAbstract:We tested the hypothesis that the H2-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for Groundwater contamination. We conducted bench-scale experiments with three Groundwater samples collected from California’s San Joaquin Valley and on two synthetic Groundwaters containing selenate and chromate. The actual Groundwater sources had nitrate levels exceeding 10 mg-N l−1 and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual Groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l−1. Present in two Groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 µg-ClO4 l−1. As(V) was substantially reduced to As(III) for two Groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 µg-As l−1. DBCP, present in one Groundwater at 1.4 µg l−1, was reduced to below its detection limit of 0.01 µg l−1, which is well below California’s 0.2 µg l−1 MCL for DBCP. For the synthetic Groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se° or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H2-based MBfR can reduce multiple oxidized contaminants simultaneously.
