Polychlorinated biphenyls and organochlorine pesticides in Baltic Sea sediments and bivalves.

The levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (p,p'-DDT, p,p'-DDD, p,p'-DDE, alpha-HCH, gamma-HCH, HCB) were determined in Baltic Sea sediments and bivalves. Concentrations of PCBs in surface sediment (0-5 cm), calculated as the sum of seven CBs (CB28, 52, 101, 118, 138, 153, 180) in one centimeter slices, ranged from 0.04 to 6.2 microg kg(-1) on a dry weight basis (dw), and from 5.8 to 78 microg kg(-1) C on a total carbon basis; corresponding sums of DDTs (p,p'-DDT, p,p'-DDD and p,p'-DDE) ranged from 0.13 to 5.0 microg kg(-1) dw and 3.6 to 160 microg kg(-1) C. The concentration ranges of alpha-HCH, gamma-HCH and HCB were found to be 0.007-0.4, 0.003-0.2 and 0.002-0.4 microg kg(-1) dw and 0.32-5.6, 0.05-3.4 and 0.19-7.5 microgkg(-1) C, respectively. In bivalves, the sum of CBs varied in the range 72-110 microg kg(-1) on a lipid weight (lw) basis (1.3-4.3 microg kg(-1) on a wet weight basis, ww), while the sum of DDTs varied from 66 to 140 microg kg(-1) (lw) (1.4-4.4 microg kg(-1), ww). The concentration ranges of alpha-HCH, gamma-HCH and HCB in bivalves were found to be 4.2-10, 4.7-11 and 3.0-6.8 mirog kg(-1) (lw) in bivalves, respectively. In surface sediments, CB 138 and CB153 were predominant among the CBs and p,p'-DDD among the DDTs, whereas in bivalves CB153, CB138 and p,p'-DDE predominated. Based on ecotoxicological assessment criteria, cause for concern regarding CBs in sediments was indicated for the Gulf of Finland and the Northern Baltic Proper. The concentration levels of DDTs and CBs in bivalves indicated the possibility of biological effects, and that even long-term biological effects are likely in the case of DDTs in the Hanö Bight (the Bornholm basin).