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VARIATION OF KOC IN SURFACE SEDIMENTS FROM NARRAGANSETT BAY AND LONG ISLAND SOUND: ANALYSIS OF THE ROLE OF OTHER PARTICULATE CHARACTERISTICS
Citation:
Ryba, S A., R M. Burgess, AND J L. Gundersen. VARIATION OF KOC IN SURFACE SEDIMENTS FROM NARRAGANSETT BAY AND LONG ISLAND SOUND: ANALYSIS OF THE ROLE OF OTHER PARTICULATE CHARACTERISTICS. Presented at Society of Enivonmental Toxicology and Chemistry Annual Meeting, Philadelphia, PA, November 14-18, 1999.
Description:
In the first part of this investigation, we examined whether differences in the Kocs of three nonpolar organic chemicals (Lindane, fluoranthene, tetrachlorinated biphenyl (PCB)) from five sites along the New England coast were statistically significant. Although no statistical differences were detected between sites, the Kocs of fluoranthene were more variable than expected. Use of Koc assumes the quantity of organic carbon is the dominant variable controlling the partitioning and bioavailability of organic contaminants in sediments. In this study, we assessed whether other sediment characteristics were also influential in affecting partitioning. To accomplish this, 18 characteristics were quantified on the particulate phase of the five sediments including elemental content (i.e., H,N,S,O), soot carbon, carbon isotope ratio and grain size. These characteristics were then used as normalizing factors (x) of the Kp of the three organic contaminants individually and in a series of combinations to generate unique coefficients (Kx = Kp/x). Unique coefficients for a total of 262, 144 combinations were compared to the effectiveness of conventional organic carbon normalization alone at reducing inter-site variability. The variability of the Kx s between sites, measured as the coefficient of variation (CV), for Lindane and the PCB was reduced by only ~5% using combinations compared to just organic carbon quantity. Conversely, the CV of the partition coefficient for fluoranthene was reduced by 23% when organic carbon, humic content and silt were combined rather than organic carbon alone. This investigation demonstrates that particulate characteristics other than the quantity of organic carbon can provide important information about the partitioning of certain organic contaminants.