Concentrations of zinc and chromium in aquatic macrophytes from the sudbury and muskoka regions of Ontario, Canada

Root and shoot samples of Eriocaulon septangulare, Nuphar variegatum, Nymphaea odorata and Pontederia cordata were collected from 15 lakes in central Ontario during the summer of 1988 to investigate possible relationships between zinc and chromium levels in aquatic macrophytes and water and sediment variables. Although concentrations of zinc and chromium differed greatly among the four species, both metals were consistently higher in Eriocaulon. Generally, root and rhizome tissue contained higher zinc and chromium than shoot tissues of the same species and site. Zinc concentrations (dry weight) ranged from 6·3 μg g −1 in Nuphar shoots to 87·7 μg g −1 in whole Eriocaulon. Chromium ranged from 0·23 μg g −1 in Pontederia shoots to 23·9 μg g −1 in whole Eriocaulon. No significant trends were detected throughout the growing season in macrophyte or sediment concentrations of either metal. Results of multiple linear regression analyses of several water quality and environmental variables on Eriocaulon indicated that sediment zinc was the best predictor of plant zinc, and sediment chromium and calcium were the best predictors of plant chromium.