A COMPARISON OF SEDIMENT TOXICITY TEST METHODS AT 3 GREAT LAKE AREAS OF CONCERN

The significance of sediment contamination is often evaluated using se diment toxicity (bioassay) testing. There are relatively few ''standar dized'' test methods for evaluating sediments. Popular sediment toxici ty methods examine the extractable water (elutriate), interstitial wat er or whole (bulk) sediment phases using test species spanning the aqu atic food chain from bacteria to fish. The current study was designed to evaluate which toxicity tests were most useful in evaluations of se diment contamination at three Great Lake Areas of Concern. Responses o f 24 different organisms including fish, mayflies, amphipods, midges, cladocerans, rotifers, macrophytes, algae, and bacteria were compared using whole sediment or elutriate toxicity assays. Sediments from seve ral sites in the Buffalo River Calumet River (Indiana Harbor), and Sag inaw River were rested as part of the U.S. Environmental Protection Ag ency's (USEPA) Assessment and Remediation of Contaminated Sediments (A RCS) Project. Results indicated several assays to be sensitive to sedi ment toxicity and able to discriminate between differing levels of tox icity. Many of the assay responses were significantly correlated to ot her toxicity responses and were similar based on factor analysis. For most applications, a test design consisting of two To three assays sho uld adequately detect sediment toxicity, consisting of various groupin gs of the following species: Hyalella azteca, Ceriodaphnia dubia, Chir onomus riparius, Chironomus tentans, Daphnia magna, Pimephales promela s, Hexagenia bilineata, Diporeia sp., Hydrilla verticillata, or Lemna minor.