Uptake and phytotransformation of o,p '-DDT and p,p '-DDT by axenically cultivated aquatic plants

The uptake and phytotransformation of o,p'-DDT and p,p'-DDT were investigat ed in vitro using three axenically cultivated aquatic plants: parrot feathe r (Mariophyllum aquaticum), duckweed (Spirodela oligorrhiza), and elodea (E lodea canadensis). The decay profile of DDT from the aqueous culture medium followed first-order kinetics for all three plants. During the 6-day incub ation period, almost all of the DDT was removed from the medium, and most o f it accumulated in or was transformed by these plants. Duckweed demonstrat ed the greatest potential to transform both DDT isomers; 50-66% was degrade d or bound in a nonextractable manner with the plant material after the 6-d ay incubation. Therefore, duckweed also incorporated less extractable DDT ( 32-49%) after 6 days than did the other plants. The capacity for phytotrans formation/binding by elodea is between that of duckweed and parrot feather; similar to 31-48% of the spiked DDT was degraded or bound to the elodea pl ant material. o,p'-DDD and p,p'-DDD are the major metabolites in these plan ts; small amounts of p,p'-DDE were also found in duckweed (7.9%) and elodea (4.6%) after 6 days. Apparently, reduction of the aliphatic chlorine atoms of DDT is the major pathway for this transformation. This study, which pro vides new information on plant biochemistry as related to pollutant accumul ation and phytotransformation, should advance the development of phytoremed iation processes.