Cadmium accumulation and bioavailability in coontail (Ceratophyllum demersum L.) plants

The aquatic vascular plant (Ceratophyllum demersum L.) was investigated as a potential biological filter for removal of Cd from wastewaters. Plants were grown in and harvested weekly from 0.10 M Hoagland nutrient solutions containing concentrations of Cd from 0.01 to 1.03 μg Cd mL−1. Tissue Cd was positively correlated to increased concentrations of Cd in solution. Concentration factors (CFs) of Cd in plants after one week were 13.3 for the 0.01 μg Cd mL−1 treatment; 451.4 for plants treated with 0.04 μg Cd mL−1, and 506.5 for plants treated with 1.03 μg Cd mL−1. Plants treated with 0.01 μg Cd mL−1 sustained tissue Cd concentrations almost 9-fold over those at week 1. However, after 5 weeks tissue Cd concentration in plants exposed to 1.03 μg Cd mL−1 had decreased 97% compared to the week 1 concentration. Growth measurements of dry weight, stem lengths, and lateral shoot growth were nagatively correlated to increased Cd treatments. Our results suggest that Coontail exposed to very low Cd concentrations (0.01 μg Cd mL−1) can take up and accumulate Cd. However, plants exposed to Cd at 0.04 μg Cd mL−1 or above did not accumulate Cd past one week.