PCBS AND PCDD FS IN LAKE-SEDIMENTS OF GROSSER ARBERSEE, BAVARIAN FOREST, SOUTH GERMANY/

Despite their environmental importance, there are still relatively few historical studies of the environmental occurrence of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), especially in middle Europe. Trends in PCBs and PCDD/Fs we re, therefore, assessed in lake sediments of the Grober Arbersee over the past 130 years (1860-1990). Ballschmiter-PCB concentrations (conge ners # 28, 52, 101, 138, 153, 180) increased between 1946 and 1972 fro m 4.2 to 32.O mu g kg(-1) dry wt, but have since decreased to 25.6 mu g kg(-1) dry wt. High chlorinated PCB congeners reached their maxima e arlier (1968-1972) than low chlorinated congeners (1985-1991). These t rends were consistent with patterns expected from the production and u se of PCBs and their precursors. PCDDIF concentrations increased betwe en 1950 from 0.6 mu g kg(-1) dry wt to 2.3 mu g kg(-1) dry wt in 1977, falling to 1.7 mu g kg(-1) dry wt by 1993. PCDF concentrations exceed ed those of PCDD until 1968, but afterwards PCDDs (especially OCDD) we re predominant. These patterns suggest that domestic heating and waste combustion were the most likely sources, but pollution from local ind ustries, such as metal smelting and glass production, might also have been involved. The data provide a valuable case study from central Eur ope which confirms the overall declining trends of PCB and PCDDIF cont amination shown elsewhere. (C) 1997 Elsevier Science Ltd.