Chlorine-containing pesticides and polychlorinated biphenyls in British coastal waters

Abstract

Gas chromatographic procedures have been developed for the determination of PCBs, DDT residues (∑DDT) and dieldrin in seawater, marine sediments and marine air. In order to minimize contamination, chlorinated hydrocarbons were concentrated from seawater in situ using a towed ‘fish’. Sampling was carried out in 1974 in the eastern Irish Sea, the Firth of Clyde, northern Scottish coastal waters, the English Channel and North Sea. Concentrations of PCBs in areas subject to least pollution averaged ~0·2 ng l −1, a value considerably lower than that found by most previous workers, which may reflect a continuation of the decline in their surface concentration reported by Harvey et al., (1974). The chromatograms of the PCB concentrates from all these areas closely matched that of Aroclor 1254. Higher concentrations (up to 1·5 ng l −1) were found in the Clyde Estuary, Liverpool Bay and the North Sea, particularly in the vicinity of sludge dumping areas, and the chromatograms of samples from such areas often matched that of Aroclor 1260. The levels of ∑DDT in the English Channel and northern Scottish waters ranged from below detection level (< 0·01 ng l −1) to 0·03 ng l −1. Samples from the Liverpool Bay area and the mouth of the River Wyre were considerably higher (~0·2 ng l −1); such samples were also the richest in dieldrin (0·04 – 0·3 ng l −1) which was usually at, or below, the detection limit (0·01 ng l −1) in samples from offshore areas. Determinations of chlorinated hydrocarbons were carried out on sediments and suspended particulates from the Irish Sea; in general, the levels in the latter were considerably higher than those in the former. A limited number of estimations were carried out on marine air, these showed the presence of 0·2 – 0·8 ng PCBs m −3, usually matching a mixture of Aroclor 1254 and 1242.