FIELD MEASUREMENTS OF PCB VOLATILIZATION FROM CONTAMINATED LAKE SEDIMENTS AND SURFACE WATERS

摘要

Between 1955 and 1978, capacitors were manufactured at the Sangamo-Weston plant, South Carolina. PCB releases into the environment resulted in sediment contamination at the Sangamo-Weston/Twelvemile Creek/Lake Hartwell Superfund Site. Sangamo-Weston reported using Aroclors 1016, 1242, and 1254. This study consisted of a field investigation that was conducted at Lake Hartwell to determine measurable levels of volatilized PCBs occurring from PCB-contaminated shoreline sediments and from the lake-water surface. Flux chambers were designed, constructed, and deployed at locations corresponding with the United States Army Corps of Engineers (USACE) transect locations T-12, T-L, and T-O to trap volatilized PCBs over sediments and the lake surface. Sediment flux sampling was conducted for periods of 24- and 72 hours over surface- and deeper more contaminated sediments. Lake surface flux sampling was conducted over a 72-hour period. Volatilized PCBs were trapped onto pre-cleaned, certified, polyurethane foam cartridges (PUFs). Sediment and water samples were also collected at the sediment flux sampling locations. Other operational measurements included airflow rate, ambient and internal flux sampler temperatures, and barometric pressure. The PUF, water, and sediment samples were analyzed by GC/MS using EPA SW-846 8270M, from which 51 PCBs congeners were identified and resolved. Total PCB data was used to calculate net fluxes for the various sampling locations. PCB flux rates for surface sediments were 0.6 to 1 μg/m~2-day; deeper sediments (after removing the upper 15 cm of sediment) were 6 to 9 μg/m~2-day; and surface waters were 55 to 140 ng/m~2-day. Congener specific distributions for sediment, water, and air samples were analyzed and showed that PCB volatilization favored lower-chlorinated, and hence lower molecular weight, PCBs. The work presented herein summarizes this research and does not represent policy of the United States Environmental Protection Agency (U.S. EPA).