ATMOSPHERIC CONCENTRATIONS OF POLYCHLORINATED-BIPHENYLS AT BLOOMINGTON, INDIANA

Air samples were collected at Bloomington, IN, in 1993 and analyzed fo r PCBs. Bloomington has several PCB sources and is the location of thr ee U.S. Environmental Protection Agency Superfund sites. The 1993 data were compared to 1986-1987 data for the same site after correcting fo r 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 vaporiz ation 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 PC Bs from Bloomington to the atmosphere using two methods. The first yie lded a range of 16 to 60 mu g m(-2) year(-1); this took into account c hanges 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 r esults of the two methods gives a total flux range of 16-165 mu g m(-2 ) year(-1).