Trace elements and synthetic organic compounds in biota and streambed sediment of the Western Lake Michigan Drainages, 1992-1995

Sampling was conducted in 1992,1994, and 1995 to determine the occurrence of a broad suite of trace elements and synthetic organic compounds in biota and streambed sediment in selected streams in the Western Lake Michigan Drainages a study unit of the National Water- Quality Assessment (NAWQA) Program of the U.S. Geological Survey. Sediment was sampled at 31 sites for trace elements and 23 sites for synthetic organic compounds; biota were collected at a subset of sites. Some of the variability in trace elements and synthetic organic compounds was related to land use, and many differences in trace element concentration by land use category were statistically significant. The spatial distribution of some trace elements was related to a combination of land use and surficial deposits and (or) bedrock type. Urban land use was likely the dominant factor influencing high sediment concentrations of Cd, Cu, Hg, and Pb. Forested land use was related to high concentrations of As in sediment and biota and high Se in sediment; however, bedrock type was an additional factor for As and surficial deposits type was a factor for Se. Land use, surficial deposits, and bedrock type appeared to influence Ni and Zn concentrations, and Cr concentrations did not directly reflect any of these factors. Most occurrences of organochlorine compounds in sediment and biota were related to urban land use. DDT and related compounds were detected at sites spanning all land uses. PCBs were detected in sediment at large-river sites and at one urban site in the Milwaukee area; the highest concentrations of PCBs in fish were found at two of four large river sites. A larger number of SVOCs were detected at urban sites and large river sites compared to agricultural and forested sites.