HR: 1330h
AN: NB33L-06    [Abstracts]
TI: Influence of Elevated Levels of Arsenic on Microbial Activity in a Headwater Stream
AU: * Reinhardt, L P
EM: reinharn@vt.edu
AF: Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 United States
AU: Lottig, N R
EM: nlottig@vt.edu
AF: Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 United States
AU: Valett, H M
EM: mvalett@vt.edu
AF: Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 United States
AU: Schreiber, M E
EM: mschreib@vt.edu
AF: Department of Geological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 United States
AB: Microbial communities play central roles in nutrient uptake, metabolism and leaf decomposition in streams. Research has shown that metazoans are extremely sensitive to arsenic pollution but microbial communities and processes appear more resistant to the influences of heavy metals and metalloids. In the case of arsenic and phosphorus, the dominant forms in aquatic ecosystems, (i.e., arsenate and phosphate) are chemically analogous. This makes it difficult for an organism to differentiate between these two molecules, potentially increasing arsenic toxicity under P-limiting situations. The primary goal of this study was determine how low phosphate concentrations and elevated levels of arsenic affected microbial activity in a headwater stream adjacent to an abandoned arsenic mine. Microbial respiration and phosphorus uptake measured on leaves and rocks were compared between an upstream (reference) and a `disturbed' reach adjacent to the arsenic mine during fall of 2004. Arsenic in stream water was <10 ppb in the reference reach and increased to 1000 ppb at the bottom of the mine-influenced reach. Soluble reactive phosphorus concentrations were <10 ppb and nitrate concentrations ranged from 400 to 800 ppb across both reaches. Microcosm respiration (0.7-1.1 g O2/m2/d) and P uptake rates (80-1600 μg P/m2/d) were influenced by arsenic toxicity.
DE: 0400 Biogeosciences
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly