PARENT SESSION
PMA17 - PBTs in Aquatic Environment
8:00 AM to 6:30 PM - Monday, November 12, 2001
Exhibit Hall A
(PM252) Occurrence and Distribution of Biologically-Mediated Reductive Dechlorinating Activity in Great Lake Sediments.
Davis, John1, Goodwin, Patrick1, Klecka, Gary1, Markham, Dan1, Alm, Elizabeth2, 1 2
ABSTRACT- The presence of chlorinated organic chemicals in aquatic sediments has been identified as a source of concern in the Great Lakes Basin. There is strong evidence beginning to accumulate suggesting that biologically mediated reductive dechlorination is responsible for the degradation of chlorinated compounds in anoxic aquatic sediments. However, questions still remain as to the occurrence and distribution of this natural dechlorinating activity in the Great Lakes sediments. To address these issues laboratory studies were conducted to evaluate the anaerobic degradation of a series of chlorinated organic chemicals (hexachlorobenzene [HCB], octachlorostyrene [OCS], and carbon tetrachloride [CCl4]) in sediments obtained from the five Great Lakes. Results to date have shown biologically mediated degradation of both HCB and CCl4 in most of the Great Lakes sediments systems. Half-lives for HCB range from 21 weeks to <61 weeks with 1,3 di- and 1,3,5- trichlorobenzene being the most common degradation metabolites. Half-lives for CCl4 are much shorter in the range of <2 weeks. Biologically mediated reductive dechlorination of octachlorostyrene to hexachlorostyrene was also observed in sediments collected from Lake Huron. Analysis of total community rRNA was used to evaluate the sediment microbial community structure from the laboratory microcosms. Results from analyses with phylogenetic specific probes demonstrated an enrichment of organisms from the Archae domain in sediments with increased levels of reductive dechlorinating activity.
Key words: Aquatic Sediments, Reductive Dechlorination, Biodegradation, Great Lakes