The Accumulation of Cadmium by the Yellow Pond Lily, Nuphar variegatum, in Ontario Peatlands

Abstract.

Cadmium concentrations of a common macrophyte, the yellow pond lily (Nuphar variegatum) were investigated from peatlands with a range in pH (4.4–6.3), alkalinity (0–181 μeq/L Ca), DOC (5.1–16.8 mg/L), and sediment organic content (20–88%). Cd concentrations in Nuphar ranged from 0.3 to 1.51 μg/g in the leaves and from 0.46 to 1.51 μg/g in the petioles, and was significantly higher in the petioles than in the leaves (p = 0.014; t-Test). Significant and negative correlations between Nuphar leaf Cd and pH (r²= 0.76; p < 0.001), alkalinity (r²= 0.41; p = 0.034), and DOC (r²= 0.46; p = 0.022) were obtained. In addition, a significant and negative correlation was found between Nuphar petiole Cd and pH (r²= 0.46; p = 0.023). These results indicate that the leaves of Nuphar found in peatlands of low pH, low alkalinity, and low DOC, and the petioles of Nuphar found in peatlands of low pH are more susceptible to accumulating potentially toxic levels of Cd. The organic content of the peatland sediments was not significantly correlated with either the leaf or petiole Cd concentration. Nuphar is an important food source for many wetland animals; any Cd that is present in these plants may be passed onto other trophic levels because diet is considered to be the major source of Cd to animals.