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(390) Influence of physical and chemical characteristics of sediments on metal uptake and toxicity. Ross, Philippe1, Clements, William2, Pearson, Joshua1, Ranville, James1, Walski, Kristina2, 1 2 ABSTRACT- Past mining of metal sulfide ores in the Rocky Mountain region has released significant quantities of low pH, metal-rich water to area streams. Natural neutralization of these waters results in the in-stream precipitation of hydrous iron oxides. Heavy metals are sorbed and co-precipitated with these oxides and are removed from the water column. In some areas these oxides are the major component of the suspended and bed sediments. Ingestion of these sediments provides a dietary route of metal exposure for some aquatic organisms. We examined the physical (grain size, specific surface area) and chemical (trace metal, iron, and organic matter content) characteristics of bed sediments collected from a mining impacted stream in Colorado. Toxicity tests were performed with Vibrio fischeri, Daphnia magna and Chironomid larvae. The influence of the measured sediment characteristics on the aquatic toxicity results was examined. The relative importance of exposure to dissolved metal versus dietary uptake of metal-contaminated sediments was also examined. In particle-size fractionation experiments, sediment grain size was strongly associated with sorbed metal content. Key words: metals, sediments, toxicity, dietary uptake |
