ABSTRACT
Radiolabeled hydrocarbons and phenols were added to water samples from the Skidaway and Cooper Rivers, two estuarine rivers on the U.S. south Atlantic coast. The adsorption of hydrocarbons to particles and microbial degradation of different petroleum components were the processes studied. Alkanes, low molecular weight aromatics (benzene, toluene, naphthalene and methylnaphthalene) and phenols were rapidly degraded to 14CO2. Low degradation rates were observed for the higher weight polycyclic aromatic hydrocarbons, fluorene, anthracene, benz(a)anthracene, and benz(a)pyrene, and from 12 to 70% of these hydrocarbons were absorbed to suspended particles in the water. Radioauto graphs of particles after the addition of 3H-benz(a)pyrene and 3H-hexadecane to the water samples indicated the hydrocarbons associated with detrital particles. This detritus was composed of a mixture of clay, organic matter, plankton remains and living microbes. One area of the Cooper River had visible oil slicks and the degradation rates of added heptadecane (20 μg/l), naphthalene (30 μg/l) and methylnaphthalene (30 μg/l) were 0.4, 2.8 and 1.1 μg/I/day, respectively. In contrast, at a downstream site, where there were no visible slicks, the degradation rate of these same hydrocarbons were 0.1, 0.7 and 0.1 μg/l/day, respectively. Estuarine water had much higher hydrocarbon degradation rates than offshore and Gulf Stream waters.