Effects of metal mixture (Cu, Zn, Pb and Ni) on cadmium partitioning in littoral sediments and its accumulation by the freshwater macrophyte Eriocaulon septangulare

The effect of mixtures of metals on cadmium fractionation in sediment and accumulation in freshwater macrophytes was determined from in-situ experiments in the littoral zone at the Experimental Lakes Area, northwestern Ontario. The distribution of cadmium among easily reducible (ER), reducible (R-ER) and organic (ORG) sediment fractions, among pore water and macrophytes was determined in a 10 week period. Mixtures of copper, zinc, lead and nickel influenced the cadmium distribution among geochemical fractions. At the highest metal concentrations, cadmium repartitioned from the ER fraction to the R-ER fraction after 2 weeks in-situ. After 10 weeks, cadmium was accumulated by the shoots and roots at 2.6 and 45 ug per g dry weight, respectively, of Eriocaulon septangulare. Significantly higher cadmium concentrations were found in shoots in the treatment with cadmium alone or with the highest concentration of metals. The partitioning of cadmium among the geochemical fractions could not explain differences in tissue concentrations of cadmium when related to treatment levels. There are 53 references.