Chemical extraction results of aquifer sediments for concentrations of iron and arsenic in different redox zones at the crude-oil spill site near Bemidji, Minnesota
In a crude-oil-contaminated sandy aquifer at the Bemidji site in northern Minnesota, biodegradation of petroleum hydrocarbons has resulted in release of naturally occurring As to groundwater under Fe-reducing conditions. This data set was collected for a study that used chemical extractions of aquifer sediments collected in 1993 and 2011-2014 to evaluate the relationship between Fe and As in different redox zones (oxic, methanogenic, Fe-reducing, anoxic-sub-oxic transition) of the contaminated aquifer over a twenty year period. The data presented showed that 1) the aquifer has the capacity to naturally attenuate the plume of dissolved As, primarily through sorption; 2) Fe and As are linearly correlated in sediment across all redox zones, and a regression analysis between Fe and As reasonably predicted As concentrations in sediment from 1993 using only Fe concentrations; 3) an As-rich “iron curtain,” associated with the anoxic-sub-oxic transition zone, migrated 30 m downgradient between 1993 and 2013 as a result of the hydrocarbon plume evolution; and 4) silt lenses in the aquifer preferentially sequester dissolved As, though As is remobilized into groundwater from sediment after reducing conditions are established.
Complete Metadata
| accessLevel | public |
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| description | In a crude-oil-contaminated sandy aquifer at the Bemidji site in northern Minnesota, biodegradation of petroleum hydrocarbons has resulted in release of naturally occurring As to groundwater under Fe-reducing conditions. This data set was collected for a study that used chemical extractions of aquifer sediments collected in 1993 and 2011-2014 to evaluate the relationship between Fe and As in different redox zones (oxic, methanogenic, Fe-reducing, anoxic-sub-oxic transition) of the contaminated aquifer over a twenty year period. The data presented showed that 1) the aquifer has the capacity to naturally attenuate the plume of dissolved As, primarily through sorption; 2) Fe and As are linearly correlated in sediment across all redox zones, and a regression analysis between Fe and As reasonably predicted As concentrations in sediment from 1993 using only Fe concentrations; 3) an As-rich “iron curtain,” associated with the anoxic-sub-oxic transition zone, migrated 30 m downgradient between 1993 and 2013 as a result of the hydrocarbon plume evolution; and 4) silt lenses in the aquifer preferentially sequester dissolved As, though As is remobilized into groundwater from sediment after reducing conditions are established. |
| distribution |
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| identifier | http://datainventory.doi.gov/id/dataset/USGS_5909fc1be4b0fc4e44916002 |
| keyword |
[
"USGS:5909fc1be4b0fc4e44916002",
"arsenic",
"biodegradation",
"biogeochemical cycling",
"sediment geochemistry",
"water chemistry",
"water quality"
]
|
| modified | 2020-08-31T00:00:00Z |
| publisher |
{
"name": "U.S. Geological Survey",
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|
| spatial | -95.646972655946, 47.28303200061, -94.02099609351, 48.169824217141 |
| theme |
[
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|
| title | Chemical extraction results of aquifer sediments for concentrations of iron and arsenic in different redox zones at the crude-oil spill site near Bemidji, Minnesota |
