Factors influencing polycyclic aromatic hydrocarbon distributions in South Carolina estuarine sediments

Surface (2 cm) sediment was collected from three South Carolina estuaries, Winyah Bay, Charleston Harbor and the North Edisto River estuary for a total of 64 samples. The sediment samples were analyzed for 24 individual polycyclic aromatic hydrocarbons (PAHs; two to six rings) by gas chromatography with ion trap mass spectrometric detection. Concentrations of total PAHs were extremely variable, ranging from 33 ng/g dry weight in the Edisto River estuary to 9600 ng/g dry weight in some areas of urbanized Charleston Harbor. The observed variability was not explained by total organic carbon or grain size, indicating that other factors were more important, such as the proximity of the sampling location to sources. Principal components analysis was performed on the percentage of total PAHs, to examine factors that account for the variability of distribution of individual PAHs in a sample. Considering this analysis, the first principal component accounted for 65% of the variability and was related to variations in perylene, a non-anthropogenically produced PAH. The principal components calculated on the PAH distributions in the absence of perylene were related to the fraction of pyrogenic and petroleum-based PAHs in the samples. The majority of the samples with pyrogenic PAH signatures were located adjacent to urban areas, suggesting that the source was urban runoff, whereas samples with petroleum signatures were generally from rural areas. (C) 1997 Elsevier Science B.V.