Prev. Article Next Article Table of Contents

Article

Microbial Mobilization of Arsenic from Sediments of the Aberjona Watershed

Dianne Ahmann,*^†^‡ Lee R. Krumholz,^†^§ Harold F. Hemond,^† Derek R. Lovley, and François M. M. Morel^†

Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003

Environ. Sci. Technol., 1997, 31 (10), pp 2923–2930

DOI: 10.1021/es970124k

Publication Date (Web): September 30, 1997

Corresponding author phone: (919) 613-8027; fax: (919) 684-8741; e-mail: dianne@duke.edu.

†

Massachusetts Institute of Technology.

‡

Current address: Nicholas School of the Environment, Duke University, Durham, NC 27708.

Current address: Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019.

University of Massachusetts.

Current address: Department of Geological Sciences, Princeton University, Princeton, NJ 08544.

Abstract

Arsenic mobilization from aquatic sediments is an issue of concern, as water-borne arsenic can migrate into pristine areas, endangering aquatic organisms and people. Such mobilization in the Aberjona Watershed has distributed nearly 20 t of arsenic throughout river and lake sediments. To gain an understanding of possible biological mechanisms contributing to this transport, mobilization of solid-phase arsenic was investigated in upper Aberjona sediment microcosms. Microcosms catalyzed rapid dissolution of arsenic from iron arsenate, a solid-phase surrogate for sedimentary arsenic, mobilizing 20−28% of the arsenic present. Sterilization prevented this transformation. Reduction of arsenate to arsenite accompanied iron arsenate dis solution, suggesting that reduction was driving dissolution. Sediment-conditioned, filter-sterilized medium showed no arsenic-transforming activity. A native enrichment culture of sulfate-reducing bacteria possessed one-fifth of the microcosm activity, while strain MIT-13, a native arsenate-reducing microorganism, showed much greater activity, dissolving 38% of the arsenic present. Furthermore, strain MIT-13 mobilized arsenic from presterilized, unamended upper Aberjona sediments. These observations indicate that a direct microbial arsenic-mobilizing activity exists in the sedi ments, show that strain MIT-13 is a strong arsenic-transforming agent native to the sediments, and suggest that dissimilatory arsenic reduction may contribute to arsenic flux from anoxic sediments in the most arsenic-contaminated region of the Aberjona Watershed.

View: Full Text HTML | Hi-Res PDF