Sediment burial of PCBs in the offshore Baltic Sea

In 1993, a large-scale investigation of polychlorinated biphenyls (PCBs) in Baltic Sea sediments was performed in cooperation between the Baltic state s, sPCB (IUPAC # 52, 101, 118, 105, 153, 138, 180) in surficial sediments i ncreased from north (mean 213 ng g(-1) C) to south (mean 382 ng g(-1) C), i ndicating atmospheric influence. In contrast to decreasing PCB trends in pe lagic biota, the sPCB in dated sediment cores from the Baltic proper showed increased or constant concentrations during recent decades. Down-core cong ener patterns showed no changes during the 20th century. After re-calculati on of sPCB deposition, assuming interannually variable dry matter depositio n, the sPCB sediment deposition trend matches the observed sPCB concentrati on trend in Baltic biota although the reductions in recent decades are less for the sediments. A calculation of sediment burial of sPCB indicated that laminated Baltic proper sediments are efficient traps, and a mass balance showed that the sPCB retention time in the water mass is less than one year .