TY - JOUR
T1 - Uranium Retention in a Bioreduced Region of an Alluvial Aquifer Induced by the Influx of Dissolved Oxygen
AU - Pan, Donald
AU - Williams, Kenneth H.
AU - Robbins, Mark J.
AU - Weber, Karrie A.
N1 - Funding Information:
U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research funded the work under contracts DE-SC0004113 (K.A.W., University of Nebraska-Lincoln) and DE-AC02-05CH11231 (Lawrence Berkeley National Laboratory; operated by the University of California). This material is partially based upon work supported through the Lawrence Berkeley National Laboratory's Sustainable Systems Scientific Focus Area. Additional support for provided by the United States Geological Survey 104g Program (2014NE265G) and National Science Foundation IGERT Fellowship (0903469) for K.A.W. and D.P., respectively.
Funding Information:
U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research funded the work under contracts DE-SC0004113 (K.A.W., University of Nebraska− Lincoln) and DE-AC02-05CH11231 (Lawrence Berkeley National Laboratory; operated by the University of California). This material is partially based upon work supported through the Lawrence Berkeley National Laboratory’s Sustainable Systems Scientific Focus Area. Additional support for provided by the United States Geological Survey 104g Program (2014NE265G) and National Science Foundation IGERT Fellowship (0903469) for K.A.W. and D.P., respectively.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/8/7
Y1 - 2018/8/7
N2 - Reduced zones in the subsurface represent biogeochemically active hotspots enriched in buried organic matter and reduced metals. Within a shallow alluvial aquifer located near Rifle, CO, reduced zones control the fate and transport of uranium (U). Though an influx of dissolved oxygen (DO) would be expected to mobilize U, we report U immobilization. Groundwater U concentrations decreased following delivery of DO (21.6 mg O2/well/h). After 23 days of DO delivery, injection of oxygenated groundwater was paused and resulted in the rebound of groundwater U concentrations to preinjection levels. When DO delivery resumed (day 51), groundwater U concentrations again decreased. The injection was halted on day 82 again and resulted in a rebound of groundwater U concentrations. DO delivery rate was increased to 54 mg O2/well/h (day 95) whereby groundwater U concentrations increased. Planktonic cell abundance remained stable throughout the experiment, but virus-to-microbial cell ratio increased 1.8-3.4-fold with initial DO delivery, indicative of microbial activity in response to DO injection. Together, these results indicate that the redox-buffering capacity of reduced sediments can prevent U mobilization, but could be overcome as delivery rate or oxidant concentration increases, mobilizing U.
AB - Reduced zones in the subsurface represent biogeochemically active hotspots enriched in buried organic matter and reduced metals. Within a shallow alluvial aquifer located near Rifle, CO, reduced zones control the fate and transport of uranium (U). Though an influx of dissolved oxygen (DO) would be expected to mobilize U, we report U immobilization. Groundwater U concentrations decreased following delivery of DO (21.6 mg O2/well/h). After 23 days of DO delivery, injection of oxygenated groundwater was paused and resulted in the rebound of groundwater U concentrations to preinjection levels. When DO delivery resumed (day 51), groundwater U concentrations again decreased. The injection was halted on day 82 again and resulted in a rebound of groundwater U concentrations. DO delivery rate was increased to 54 mg O2/well/h (day 95) whereby groundwater U concentrations increased. Planktonic cell abundance remained stable throughout the experiment, but virus-to-microbial cell ratio increased 1.8-3.4-fold with initial DO delivery, indicative of microbial activity in response to DO injection. Together, these results indicate that the redox-buffering capacity of reduced sediments can prevent U mobilization, but could be overcome as delivery rate or oxidant concentration increases, mobilizing U.
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U2 - 10.1021/acs.est.8b00903
DO - 10.1021/acs.est.8b00903
M3 - Article
C2 - 29996052
AN - SCOPUS:85049854620
VL - 52
SP - 8133
EP - 8145
JO - Environmental Science & Technology
JF - Environmental Science & Technology
SN - 0013-936X
IS - 15
ER -