Warner, K. A. University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, warner@cbl.umces.edu
Capone, D. G. UMCES Chesapeake Biological Laboratory, capone@cbl.umces.edu

 
HYDROGEN DISTRIBUTIONS IN CHESAPEAKE BAY SEDIMENTS IN RELATION TO REDUCTIVE DECHLORINATION ACTIVITY AND BIOGEOCHEMICAL PARAMETERS
 
Hydrogen concentrations in Chesapeake Bay sediments were determined in conjunction with several biogeochemical parameters at three sites along the Bay's salinity gradient in an attempt to define environmental parameters relevant to the onset of microbial reductive dechlorination (RD) of a model compound, 2,4-dichorophenol. Sulfate is often inhibitory to RD and this may be due to more successful competition for electron donors, such as hydrogen, under sulfate reducing conditions. We hypothesized that hydrogen concentrations should increase under sulfate limitation and become more available for RD. Hydrogen concentrations in sediment incubations increased several orders of magnitude upon sulfate depletion at a mid Bay site and coincided with rapid RD rates. Estimated hydrogen production rates appeared to support < 1% of sulfate reduction rates at this site. Although sulfate reduction dominates terminal metabolism at all three sites, steady state hydrogen concentrations increased in the seaward direction, indicating the possible contribution of alternative electron accepting processes. Bioturbation at some of the sites appeared to affect the hydrogen concentrations by influencing the distribution and oxidation state of electron acceptors other than sulfate. The rate of net hydrogen production and distribution of labile carbon appeared to be the most important factors governing RD rates.
 
Day: Thursday, Feb. 4
Time: 08:45 - 09:00am
Location: Hilton of Santa Fe
 
Code: SS30FR0845S