UPTAKE AND TRANSLOCATION OF SELECTED ORGANIC PESTICIDES BY THE ROOTED AQUATIC PLANT HYDRILLA-VERTICILLATA ROYLE

Rooted aquatic vascular plants are exposed to both overlying water and sediment and are able to absorb nutrients and chemicals from both of these environments. Translocation of sediment-retained contaminants by plants presents the possibility of contaminant redistribution into the water column or food chain. For [C-14]atrazine exposure in solution, uptake and release approached equilibrium within 1 and 2 h for shoot and root tissue, respectively. [C-14]Lindane and [C-14]chlordane concentrations in the root and shoot reached equilibrium within 24 and 144 h, respectively. Bioconcentration factors (BCF) for hydrilla were 9.62, 38.15, and 1060.95 for atrazine, lindane, and chlordane, respectively. BCF estimation methods using log octanol-water partition coefficient and log water solubility based on data from fish or duckweeds were not predictive of values for hydrilla. All three chemicals were translocated acropetally from the roots in a spiked sediment. When the 2-3-cm segment of shoot beyond the roots was considered, atrazine was in equilibrium after 6 h of root exposure. All shoot segments had similar concentrations of atrazine within 48 h after root exposure, although this concentration was slightly less than for the whole-plant exposure to the chemical in solution. Lindane concentration was in equilibrium after 192 h of root exposure at approximately 20x less than the shoot concentration for the whole-plant exposure. Chlordane concentration did not change significantly after 96 h of root exposure and was 780x less than the shoot concentration for the whole-plant exposure.