Rates of As and trace-element mobilization caused by Fe reduction in mixed BTEX–ethanol experimental plumes

Environmental Science & Technology
By: , and 

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Abstract

Biodegradation of organic matter, including petroleum-based fuels and biofuels, can create undesired secondary water-quality effects. Trace elements, especially arsenic (As), have strong adsorption affinities for Fe(III) (oxyhydr)-oxides and can be released to groundwater during Fe-reducing biodegradation. We investigated the mobilization of naturally occurring As, cobalt (Co), chromium (Cr), and nickel (Ni) from wetland sediments caused by the introduction of benzene, toluene, ethylbenzene, and xylenes (BTEX) and ethanol mixtures under iron- and nitrate-reducing conditions, using in situ push–pull tests. When BTEX alone was added, results showed simultaneous onset and similar rates of Fe reduction and As mobilization. In the presence of ethanol, the maximum rates of As release and Fe reduction were higher, the time to onset of reaction was decreased, and the rates occurred in multiple stages that reflected additional processes. The concentration of As increased from <1 μg/L to a maximum of 99 μg/L, exceeding the 10 μg/L limit for drinking water. Mobilization of Co, Cr, and Ni was observed in association with ethanol biodegradation but not with BTEX. These results demonstrate the potential for trace-element contamination of drinking water during biodegradation and highlight the importance of monitoring trace elements at natural and enhanced attenuation sites.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Rates of As and trace-element mobilization caused by Fe reduction in mixed BTEX–ethanol experimental plumes
Series title Environmental Science & Technology
DOI 10.1021/acs.est.5b02341
Volume 49
Issue 22
Year Published 2015
Language English
Publisher ACS
Contributing office(s) National Research Program - Eastern Branch, Toxic Substances Hydrology Program
Description 11 p.
First page 13179
Last page 13189