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The role of alluvial aquifer sediments in attenuating a dissolved arsenic plume data release

May 1, 2017

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.

Citation Information

Publication Year 2017
Title The role of alluvial aquifer sediments in attenuating a dissolved arsenic plume data release
DOI 10.5066/F7K35RWK
Authors Brady A. Ziegler, Madeline E. Schreiber, Isabelle M Cozzarelli
Product Type Data Release
Record Source USGS Digital Object Identifier Catalog
USGS Organization National Research Program