Metal and bacterial contamination in New Jersey estuarine sediments

Abstract

This study examines metal and bacterial contamination in sediments of the lagoons or back bays along the New Jersey shore. A total of 70 samples were taken from 24 channels scheduled for maintenance dredging and analysed for texture, total coliforms (TC), faecal coliforms (FC), faecal streptococci (FS), As, Cd, Cu, Pb, Hg, Ni and Zn. Bacterial enumerations revealed TC, FC and FS concentrations as high as 8334, 3052 and 3052 MPN g −1 dry weight, respectively. Metal concentrations were generally moderate in comparison with other estuaries in urban areas, with higher levels found in the northern part of the study area. Enrichment factors were in the range of 1 to 50 times probable background levels. TC correlated negatively with per cent sand in the samples, as did metal concentrations. FC and FS correlated poorly with texture, suggesting localised sources for these organisms. Metal concentrations were highly intercorrelated, indicating common, rather than discrete, sources. Metal and TC concentrations were highest in areas of high population density, and the absence of industrial sources suggests urban runoff is a major contributor of pollutants. The level of contaminants found in more heavily contaminated areas are high enough to warrant additional investigations prior to dredging and spoil disposal.