ATMOSPHERIC CONCENTRATIONS OF POLYCHLORINATED-BIPHENYLS AT BLOOMINGTON, INDIANA

Air samples were collected at Bloomington, IN, in 1993 and analyzed for PCBs. Bloomington has several PCB sources and is the location of three U.S. Environmental Protection Agency Superfund sites. The 1993 data were compared to 1986-1987 data for the same site after correcting for atmospheric temperature by using the Clausius-Clapeyron equation. We found that the concentrations of each congener and of total PCBs had not changed in the intervening 6 years. We calculated heats of vaporization for each congener; they had a mean of 63 +/- 16 kJ/mol. We also calculated atmospheric residence times for each congener. These had a mean value of 49 +/- 16 days. We calculated the flux of vapor-phase PCBs from Bloomington to the atmosphere using two methods. The first yielded a range of 16 to 60 mu g m(-2) year(-1); this took into account changes in atmospheric temperature. A concentration gradient model gave a flux of 53-165 mu g m(-2) year(-1) at 25 degrees C. Combining the results of the two methods gives a total flux range of 16-165 mu g m(-2) year(-1).