M8 AM Persistent Organic Pollutants
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 337-338

(AAA-1117-652527) Assessing the influence of black carbon and sorbate planarity on sorption of PCBs by Lake Hartwell sediment.

Im, J¹, Lee, C¹, Coates, J¹, ¹ Clemson University, Anderson, SC, USA

ABSTRACT- The objective of this study is to develop a better understanding of complicated environmental sorption of PCBs in natural sediment systems including the role of black carbon of different types, humic acid, and sorbate planarity. Sorption of three PCB congeners [tri-CB (IUPAC 35), and tetra-CB (IUPAC 54 and 77)] by sediment from a reservoir contaminated with PCBs but relatively free of black carbon (BC) and by sediment amended with two well-characterized black carbon materials or humic acid will be reported. The sorbents are sediment collected from Lake Hartwell located on the border between South Carolina and Georgia; black carbon reference material (BCRM), which was developed by the Black Carbon Steering Committee of the AGU; and NIST standard reference material (SRM 2975), which consists of diesel particulate matter. Elliot Soil Humic Acid was obtained from International Humic Substances Society. For both Lake Hartwell sediment suspension (less than 53 um) and kaolinite (a major component of the reservoir sediment), isotherms for the tri-CB indicated much less sorption compared to BCRM or SRM 2975. Isotherm results from the reservoir sediment with various levels of BC (0.0 %, 1.0 %, 2.0 %, 4.0 %, and 8.0 % of the Lake Hartwell sediment weight) added will be reported for the congeners. Results for the black carbon reference material (BCRM) sorbent indicated a greater affinity for the planar tri-CB (IUPAC 35) than the nonplanar tetra-CB (IUPAC 54). The PCB congeners have similar hydrophobicity, however, the planarity of two compounds are very different due to the number of chlorine attached to the ortho positions of biphenyl. For tri-CB, sorption by BCRM was greater than SRM 2975.

Key words: polychlorinated biphenyls, sorption, black carbon, sediment