Organochlorine pesticides in sediments from Long Island Sound

Surficial sediments and sediment cores were collected at various sites in Long Island Sound (LIS) previously surveyed by the National Oceanic and Atmospheric Administration (NOAA)'s National Status and Trends (NS&T) Program. Archived surficial sediments at selected sites were acquired from the NS&T Specimen Bank.;Concentrations of organochlorine pesticides (OCPs) in recently collected sediments and archived sediments from LIS were determined. OCPs are still widely present in current LIS surficial sediments two decades after the use of these pesticides in the U.S. was banned. Sediments in the western part of the Sound are more contaminated than in the eastern part and all the most contaminated sites are located in the west tip of the Sound, which is close to the high population density metropolitan area. OCPs concentrations in LIS surficial sediments (sediments from the western LIS sites in particular) exceeded several sediment quality guidelines.;The OCPs concentration profiles showed that OCPs were present in every depth of the sediment cores. Direct comparison of the 137Cs and chlordane profiles in the sediment core suggested that the maximum releases of chlordane to the Sound occurred close in time to the 137Cs fallout maximum (1963). Model simulations of the chlordane profiles suggest continual input at western LIS long after the 1980s.;The fact that chlordane in agricultural soils near LIS was greatly non-racemic but chlordane in LIS sediment in the past 60 years was racemic or near racemic suggested that runoff from agricultural soils constitutes, at most, a minor fraction of the recent input into LIS and house foundation soils are likely the major source of chlordane input into the Sound, at least for more recent input. It is probably also true that the chlordane input to LIS prior to the 1980s was from house foundation soils near urban areas.;Both continued input and significant sediment mixing may have led to persistent chlordane concentrations (and persistent organic pollutant concentrations in general) in LIS surficial sediments, posing long-term threats to benthic organisms. The lack of enantioselective microbial degradation of chlordane in LIS sediments makes it even more persistent in the Sound.