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PREFERENTIAL PARTITIONING OF A PAH AND PCB TO A MARINE SEDIMENT AMENDED WITH SEVERAL SOURCES OF SOOT CARBON
Citation:
Burgess, R M., S A. Ryba, AND R Tien. PREFERENTIAL PARTITIONING OF A PAH AND PCB TO A MARINE SEDIMENT AMENDED WITH SEVERAL SOURCES OF SOOT CARBON. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Nashville, TN, November 12-16, 2000.
Description:
Over the last decade, several studies reported that the partitioning of PAHs to sediments, in some cases, did not follow predictions based on equilibrium partitioning theory. One explanation for these differences is the presence of a second sedimentary phase with partitioning characteristics unlike natural organic carbon. Soot carbon originating from combustion of fossil fuels is most commonly put forward as an example of this second sedimentary phase. In this study, we amended a marine sediment with soot carbon from various sources, a non-soot carbon, and a non-carbon matrix. We then conducted equilibration studies with 14C fluoranthene and 3H 2,4 dichlorinated biphenyl. Soot carbon source materials included raw and aged automotive diesel soot, coal dust, class 'F' coal fly ash, and an organic carbon enriched coal fly ash. Non-soot carbon and non-carbon materials included Aldrich humic acid and muflled beach sand, respectively. The PAH and PCB share similar log Kows (5.12 vs. 5.07) and molecular weights. Furthermore, based on a linear free energy relationship, differences in the PCB and P AH log Kocs were predicted to be 0.1 log units. Consequently, we expected them to demonstrate similar partitioning behavior. However, soot carbon amended sediments generated PAH Kocs exceeding PCB Kocs by up to 1. 5 log units depending on the soot carbon source. Sediments amended with humic acid and sand showed differences of only 0.3 log units. These studies indicate a preferential interaction for P AHs with sediments containing soot carbon greatly exceeding predictions based on equilibrium partitioning theory. A better understanding of soot carbon distribution, abundance and contaminant geochemistry is required to improve our ability to predict the fate and bioavailability ofF AHs (and other planar contaminants) in the environment.