The occurrence and distribution of trace organic compounds in Bermuda precipitation

Abstract

Data are presented on the chemical composition of 36 rainwater events sampled in Bermuda during 1983 and 1984. Samples were analyzed for alpha and gamma isomers of hexachlorocyclohexane, chlordaneand dieldrin. Mean concentrations with standard errors found were 854 ± 217 pgℓ −1 for α HCH, 126 ± 27 pgℓ −1 for γ HCH, 77 ±17 pg ℓ −1 for chlordane and 158 ± 27 pgℓ −1 for dieldrin. The data indicate that higher concentrations of α HCH and γ HCH in rainwater are associated with air masses originating in North America. The concentrations of the compounds in precipitation are highly variable and the deposition of the compounds is extremely episodic. The wet fluxes of chlordane and dieldrin are discussed in relation to deep-sea sediment trap measurements collected at 3200 m in the Sargasso Sea 25 km southeast of the rainwater sampling site and indicate a wet flux of 78–115 ng m −2yr −1 for chlordane and 217–237 ng m −2yr −1 for dieldrin which is 6–8 times higher than the measured deep-sea flux.