HA1 Contaminated Harbour and River Sediment
256 Portland Ballroom
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() Comparison of Sediment Contamination in the St. Louis River Area of Concern with Other Harbors and Rivers in North America.
Crane, J.1, MacDonald, D.2, Smorong, D.2, Fisher, L.2, 1 MPCA, St. Paul, MN, USA2 MacDonald Environmental Sciences Ltd., Nanaimo, BC, Canada
ABSTRACT- The St. Louis River Area of Concern (AOC) is an important transboundary waterway between northeastern Minnesota and northwestern Wisconsin. In September 2003, the first phase of a GIS-based sediment quality database was completed for the St. Louis River AOC. The second phase of this project has recently been initiated to include additional sediment chemistry, sediment toxicity, physical parameter, and bioaccumulation data, as well as to begin incorporating benthic invertebrate community data into the database. As part of the first phase of this project, a step-wise approach was used to compare sediment chemistry data in surficial samples (0-30 cm) within the St. Louis River AOC with that in surficial sediments from other AOCs in the Great Lakes basin and in other rivers and harbors located elsewhere in North America. These steps included: identifying areas of interest included in a proprietary SedTox database owned by MacDonald Environmental Sciences Ltd., collating the sediment chemistry data, calculating summary statistics for each geographic area, evaluating the distribution of a mixture of sediment contaminants for each area (through the use of mean Probable Effect Concentration quotients, PEC-Qs), and assessing the potential effects of chemicals of potential concern on benthic invertebrates. Based on average mean PEC-Qs calculated, the St. Louis River AOC ranked fifth in terms of chemical contamination among the eight AOCs considered in this analysis. The highest levels of chemical contamination were observed in surficial sediments from the Grand Calumet River AOC, IN. Among the six other geographic areas that were considered in this analysis, the highest levels of contamination were observed in sediment samples from the Willamette River, OR. Based on the average mean PEC-Qs calculated, the St. Louis River AOC ranked second in terms of chemical contamination among the areas located outside the Great Lakes basin. When both the Great Lakes AOCs and other areas in North America were considered, the St. Louis River AOC ranked sixth among the 14 areas in terms of the levels of contamination in surficial sediments. Risks to benthic invertebrates were considered to be low if mean PEC-Qs were <0.1, moderate if mean PEC-Qs were between 0.1 and 0.6, and high if mean PEC-Qs were >0.6. These analyses will be updated after additional sediment quality data have been incorporated into the St. Louis River and SedTox databases (i.e., fall 2004).
Key words: sediment chemistry, Great Lakes , sediment quality, mean PEC-Qs