Distribution of toxic organic contaminants in water and sediments in the Detroit river

Contamination of sediments in the Detroit River has been shown to have impa cts upon the health of benthic fish in direct contact with the sediments. I t was hypothesized that hydrophobic contaminants partition from sediments i nto the aqueous phase in the Detroit River, subsequently bioaccumulating in fish and causing toxic effects. In order to assess the distribution of org anic contaminants dissolved in water relative to contamination in the sedim ents, semi-permeable membrane devices (SPMDs) were deployed and sediments w ere collected from five sites in the Detroit River and from one site in wes tern Lake Erie. Sample extracts were analyzed for concentrations of PAHs, P CBs, and selected organochlorine insecticides (DDT compounds, chlordane com pounds, and HCH isomers). Both SPMD and sediment extracts were tested for l ethality in an early life-stage mortality assay with Japanese medaka (Oryzi as latipes). The mean concentrations of PCBs, PAHs, and DDT compounds in se diments and SPMDs were highest at three sites in industrialized regions of the Detroit River; at Zug Island near the outflow of the Rouge River, at El izabeth Park in the Trenton Channel, and at Celeron Island downstream of th e Trenton Channel. The mean concentrations of contaminants in sediments and in SPMDs from the various sites were highly correlated, indicating that co ntaminants in the Detroit River are partitioning between sediments and the dissolved phase of the water column. The lethal concentrations (LC50s) of e xtracts to early life stages of medaka were highly correlated with the conc entrations of PAHs in the samples. This study illustrates the value of usin g SPMDs as devices for monitoring aquatic contamination, and the ease with which in vivo toxicity tests can be used to screen SPMD extracts prior to a nalytical studies.