A statistical approach for determining the environmental impact of polynuclear aromatic hydrocarbons in an oil spill-contaminated coastal area

Frequently, samples are collected and analyzed in order to investigate the extent of pollution in a soil or coastal zone. The resulting concentrations of pollutants at various sites are compared with the standard concentration levels in order to determine compliance with environmental regulations. These methods, however, have drawbacks when the area polluted is very large or has heterogeneous structures. In this study, a methodology is proposed which is based on the extent of pollution of polynuclear aromatic hydrocarbons (PAHs). As a model, a coastal area contaminated by an oil spill was selected and sediment samples were collected from the intertidal zone. Sixteen different PAHs were analyzed. The method involved a statistical approach, in order to obtain the probability density function, geometric standard deviation and the geometric mean for the collected data. In addition, toxicity equivalence factors (TEFs) for seven PAHs were used for estimating the pollution level. Based on the total PAH concentrations and the concentration of each PAH component, pollution probabilities above the standard pollution level set by the National Oceanic and Atmospheric Administration and the Florida Department of Environmental Regulation were calculated. The results also showed that acenaphthene and benzo(a)anthracene could be two representative components among 16 PAHs for the typical pollution index in the oil-spilled coastal region. The extent of pollution at sites could be expressed by the toxic concentration converted with the corresponding TEF of each PAH.