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A microbial arsenic cycle in sediments of an acidic mine impoundment: Herman Pit, Clear Lake, California

September 18, 2015

The involvement of prokaryotes in the redox reactions of arsenic occurring between its +5 [arsenate; As(V)] and +3 [arsenite; As(III)] oxidation states has been well established. Most research to date has focused upon circum-neutral pH environments (e.g., freshwater or estuarine sediments) or arsenic-rich “extreme” environments like hot springs and soda lakes. In contrast, relatively little work has been conducted in acidic environments. With this in mind we conducted experiments with sediments taken from the Herman Pit, an acid mine drainage impoundment of a former mercury (cinnabar) mine. Due to the large adsorptive capacity of the abundant Fe(III)-rich minerals, we were unable to initially detect in solution either As(V) or As(III) added to the aqueous phase of live sediment slurries or autoclaved controls, although the former consumed added electron donors (i.e., lactate, acetate, hydrogen), while the latter did not. This prompted us to conduct further experiments with diluted slurries using the live materials from the first incubation as inoculum. In these experiments we observed reduction of As(V) to As(III) under anoxic conditions and reduction rates were enhanced by addition of electron donors. We also observed oxidation of As(III) to As(V) in oxic slurries as well as in anoxic slurries amended with nitrate. We noted an acid-tolerant trend for sediment slurries in the cases of As(III) oxidation (aerobic and anaerobic) as well as for anaerobic As(V) reduction. These observations indicate the presence of a viable microbial arsenic redox cycle in the sediments of this extreme environment, a result reinforced by the successful amplification of arsenic functional genes (aioA, and arrA) from these materials.

Publication Year 2015
Title A microbial arsenic cycle in sediments of an acidic mine impoundment: Herman Pit, Clear Lake, California
DOI 10.1080/01490451.2015.1080323
Authors Jodi S. Blum, Shelley McCann, S. Bennett, Laurence G. Miller, J. R. Stolz, B. Stoneburner, C. Saltikov, Ronald S. Oremland
Publication Type Article
Publication Subtype Journal Article
Series Title Geomicrobiology Journal
Index ID 70175029
Record Source USGS Publications Warehouse
USGS Organization National Research Program - Western Branch