Source of Polychlorinated Biphenyl Contamination in the Marine Environment

Abstract

SINCE residues of polychlorinated biphenyls (PCBs) were identified in Swedish wildlife¹, they have been reported in many marine species^2–7. Samples of marine fish and molluscs from Scottish waters have been analysed for organochlorine residues at this laboratory on several occasions since 1965, and the concentrations of PCB residues detected in these samples have been generally highest from the Firth of Clyde. Therefore a wide variety of samples from this area was used in the autumn of 1969 to try to establish the route by which the PCB residues reached the fish. Samples of the water surface film and sub-surface water were taken at various points in the estuary, and also at 2-mile intervals along the river to the centre of Glasgow, to detect any local discharges containing PCBs, No PCB residues could be found (limit of detection in water, 1 part in 10¹¹) and samples of effluents discharged from trunk sewers into the estuary and in the Glasgow area also showed no significant concentrations of PCBs. Concentrations in zooplankton by comparison were less than 0.03 p.p.m. (3 parts in 10⁸), and in clupeoid fish up to 2.6 p.p.m. (both expressed on a wet weight basis).