Phototoxic response of Lumbriculus variegatus to sediments contaminated by polycyclic aromatic hydrocarbons

The toxicity of certain polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms can be greatly increased upon exposure of the organisms to ultraviolet (UV) radiation present in sunlight. The phenomenon of photoactivation of PAHs had received some attention in the laboratory; however, evaluation of the photoinduced toxicity of PAHs in field settings has been limited. In our studies, in situ chambers made from Pyrexr glass tubes were used to evaluate the phototoxic response of laboratory-cultured oligochaetes (Lumbriculus variegatus) in sediments contaminated with PAHs. These experiments were conducted using both sunlight-exposed and shaded test chambers. In addition to the PAH-contaminated site, a reference site lacking PAHs was tested as a control. Survival of L. variegatus at the PAH-contaminated site was significantly less in chambers exposed to sunlight than in chambers held in the dark, or chambers from the reference site. Concurrent laboratory studies with sediment collected from the two sites and an artificial source of UV light corroborated observations made in the field. Although a number of PAHs were present at elevated concentrations in the test sample, further work is required to determine exactly which were responsible for the observed phototoxicity.