IN-SITU TOXICITY EVALUATIONS OF TURBIDITY AND PHOTOINDUCTION OF POLYCYCLIC AROMATIC-HYDROCARBONS

Polycyclic aromatic hydrocarbons (PAHs) are prevalent pollutants in th e aquatic environment that can cause a wide range of toxic effects. Ea rlier studies have shown that toxicity of PAHs can be enhanced by ultr aviolet (UV) radiation. In situ and laboratory exposures with Ceriodap hnia dubia were used to evaluate photoinduced toxicity of PAHs in wet- weather runoff and in turbid conditions. Exposure to UV increased the toxicity of PAH-contaminated sediment to C. dubia. Toxicity was remove d when UV wavelengths did not penetrate the water column to the expose d organisms. A significant correlation was observed between in situ C. dubia survival and turbidity when organisms were exposed to sunlight. Stormwater runoff samples exhibited an increase in chronic toxicity ( reproduction) to C. dubia when exposed to UV wavelengths as compared t o C. dubia not exposed to UV wavelengths. Toxicity was reduced signifi cantly in the presence of UV radiation when the organic fraction of st ormwater runoff was removed. The PAHs are bound to the sediment and re suspended into the water column once the sediment is disturbed (e.g., during a storm). The in situ and laboratory results showed that photoi nduced toxicity occurred frequently during low how conditions and wet weather runoff and was reduced in turbid conditions.