Distribution of polycyclic aromatic hydrocarbons in oyster (Crassostrea virginica) and surface sediment from two estuaries in South Carolina

Abstract

The concentration of polycyclic aromatic hydrocarbons (PAHs) was determined in oysters and sediments collected from two high salinity estuaries from the coast of South Carolina. The two estuaries were Murrells Inlet (urban), an estuary receiving urbanized drainage and run-off, and North Inlet (non-urban), receiving drainage from heavily forested terrain and minimal anthropogenic input. A minimum of thirty (30 stations were sampled in Murrells and North Inlets, respectively. A composite oyster sample (n = 30) was analyzed for each station. For sediment, a sample from the top 3-5 cm of the sediment surface from each station was analyzed. In oyster from Murrells Inlet, total PAHs concentrations within the 75 percentile were located in the northern portion of the estuary near marinas, adjacent to residential areas of high population density, near commercial enterprises or run-off from storm drains. Total PAHs within the 25 percentile were located near the mouth of the estuary. These results showed PAHs concentration gradient in the estuary that was highest in narrow creeks, where the urban shore interfaced with tidal creeks and lowest at the mouth of the estuary. In the case for sediment, a similar gradient was observed. In comparing the mean total PAHs of the two inlets, Murrells Inlet had significantly higher (p < 0.01) total PAHs concentrations than North Inlet for oyster and sediment, respectively. In comparing PAHs concentrations among the two matrices in Murrells Inlet, these data showed that the pattern of individual PAHs in oyster and in sediment were different. Oysters tended to accumulate the lower molecular weight and the more water-soluble PAHs compared to PAHs found in sediment. As expected, differences in octanol/water partition coefficient among individual PAHs and the greater persistence of the higher molecular weight PAHs contributed to the accumulation patterns in oyster and sediment.