Acute Phototoxicity of Harbor and Tributary Sediments from Lower Lake Michigan

The phototoxicity of PAHs, together with their accumulation in sediments, suggest that dredging and other disturbances may pose a presently unrecognized environmental hazard. To test this, sediments contaminated with PAHs were collected from sites in the Grand Calumet River, the Indiana Harbor Canal, and Waukegan Harbor. The phototoxicity of liquid-phase elutriates was tested using Daphnia magna . Phototoxicity was found in Grand Calumet River and Indiana Harbor elutriates, both in sunlight and 354 nm near-uv. None of the elutriates was toxic in the absence of light. These results reveal an important and previously unsuspected hazard to shallow water environments near dredging sites, and describe simple methods to detect phototoxicity which will be of value in the establishment of sediment quality criteria.