CADMIUM ACCUMULATION AND BIOAVAILABILITY IN COONTAIL (CERATOPHYLLUM-DEMERSUM L) PLANTS

The aquatic vascular plant (Ceratophyllum demersum L.) was investigate d as a potential biological filter for removal of Cd from wastewaters. Plants were grown in and harvested weekly from 0.10 M Hoagland nutrie nt solutions containing concentrations of Cd from 0.01 to 1.03 mug Cd mL-1. Tissue Cd was positively correlated to increased concentrations of Cd in solution. Concentration factors (CFs) of Cd in plants after o ne week were 13.3 for the 0.01 mug Cd mL-1 treatment; 451.4 for plants treated with 0.04 mug Cd mL-1, and 506.5 for plants treated with 1.03 mug Cd mL-1. Plants treated with 0.01 mug Cd mL-1 sustained tissue Cd concentrations almost 9-fold over those at week 1. However, after 5 w eeks tissue Cd concentration in plants exposed to 1.03 mug Cd mL-1 had decreased 97% compared to the week 1 concentration. Growth measuremen ts of dry weight, stem lengths, and lateral shoot growth were nagative ly correlated to increased Cd treatments. Our results suggest that Coo ntail exposed to very low Cd concentrations (0.01 mug Cd mL-1) can tak e up and accumulate Cd. However, plants exposed to Cd at 0.04 mug Cd m L-1 or above did not accumulate Cd past one week.