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MSU SEER: Microbial Control of Arsenic Speciation and Redox Cycling in Contaminated Riverine Sediments

EPA Grant Number: R827457E03
Title: MSU SEER: Microbial Control of Arsenic Speciation and Redox Cycling in Contaminated Riverine Sediments
Investigators: McDermott, Timothy R. , Inskeep, William P.
Institution: Montana State University
EPA Project Officer: Winner, Darrell
Project Period: July 1, 1999 through June 30, 2002
Project Amount: $140,000
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (1998)
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)

Description:

Objective:

Our work on arsenic (As) biogeochemistry in As-contaminated mine tailing and soils in Montana have made it clear that microbial As redox activity in these environments is very important to As speciation. We have found that As speciation does not follow simple chemical or thermodynamic equilibria; i.e., high levels of As(V) reduction under oxidizing conditions and high levels of As(III) oxidation under anaerobic conditions. A detailed analysis of the linkage between microbial community structure and the observed redox activity is essential to understanding the relationships among As geochemistry, As transport, and As bioavailability. The proposed work will complement our current environmental As chemistry work and integrate with the work described by Holben et al. (SEER 2, University of Montana EPA-EPSCoR proposal. This proposal focuses on the following objectives:

I. Examine the effects of As concentration, carbon and oxygen availability, and pH on As redox kinetics and As species equilibria, As reducer/oxidizer population dynamics, and overall microbial community structure and diversity.

II. Isolate and/or enrich for As reducing/oxidizing organisms and consortia, and conduct initial characterization of their phylogeny, basic biochemistry, and physiology as they pertain to As redox activity.

III. Conduct in situ experiments to verify laboratory predictions obtained with batch and column incubations, enriched consortia, and pure culture isolates.

Approach:

Relationships between As speciation and microbial activity will be determined by comparing As redox kinetics with microbial population dynamics within a treatment matrix that will include As concentration, carbon and O2 availability, and pH. Microbial community-level analyses will include (RT)PCR-DGGE to monitor shifts in total diversity. 16S rDNA sequence information obtained from PCR-cloned DNA will be used to design genotype-specific molecular probes and functional gene probes will be used to track the occurrence of relevant genes in the populations of interest. Enrichment culture and dilution-extinction techniques will be used to identify and isolate As redox cycling microbes. Unculturable microbes affected by the treatment matrix will be identified by (RT)PCR-DGGE coupled with sequencing of PCR-cloned 16S rDNA. Isolated organisms and enriched consortia will be characterized for their ability to oxidize or reduce As, with the latter differentiated between dissimilatory reduction (i.e., electron acceptor) vs detoxification. We will use the same samples and sampling sites along the Silver Bow Creek and Clark Fork river as described by Holben et al (SEER 2 of the U of M proposal).

Expected Results:

This study will initiate the first detailed analysis of specific microorganisms participating in As transformations in contaminated soils and river sediments. An understanding of the microbial community structure important in As redox cycling under different environmental conditions will improve our current capabilities to predict As transport and bioavailability, and to evaluate management alternatives for the remediation of As contaminated sites.

Publications and Presentations:

Publications have been submitted on this project: View all 14 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 13 journal articles for this project

Supplemental Keywords:

bacteria, arsenic, redox, trace elements, mine tailings. , Water, INTERNATIONAL COOPERATION, TREATMENT/CONTROL, Scientific Discipline, Waste, RFA, Remediation, Chemical Engineering, Hazardous Waste, Biochemistry, Environmental Chemistry, Contaminated Sediments, Groundwater remediation, Hazardous, Treatment Technologies, Bioremediation, arsenic, biodegradation, microbial degradation, redox, Chromium, groundwater, metal removal, contaminated sediment, contaminants in soil, contaminated soils, contaminated soil, bioremediation of soils, adsorbable metals, contaminated groundwater, hazardous waste treatment, metals removal, sorption

Progress and Final Reports:
Final Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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