Metalaxyl and simazine toxicity to and uptake by Typha latifolia.

This research focused on the potential use of common cattails (Typha latifolia) for removing metalaxyl and simazine residues from contaminated water. Specifically, it established toxicity thresholds to the herbicide simazine and characterized the uptake and distribution of simazine and metalaxyl by the plants. Simazine tolerance levels were determined by exposing plants to a series of six concentrations (0-3.0 mg L(-1)) in aqueous nutrient media for 7 days. Metalaxyl toxicity was not evaluated because other studies indicated it was relatively nontoxic to plants. Toxicity endpoints measured included fresh mass production after 7 days of exposure and 7 days postexposure. Pesticide uptake and distribution were determined by growing plants in nutrient media amended with (14)C-ring-labeled metalaxyl (0.909 mg L(-1)) or simazine (0.242 mg L(-1)) for 1, 3, 5, or 7 days. Plants were dissected, and tissues were combusted and analyzed by liquid scintillation spectroscopy. Cattail fresh mass production was reduced 84 and 117% at 1.0 and 3.0 mg L(-1) simazine, respectively, after 7 days of exposure. Metalaxyl and simazine activity in solution was reduced 34 and 65%, respectively, after 7 days. By day 7, activity from both pesticides was detected predominantly in the leaves. Uptake of each pesticide was correlated with water uptake throughout the 7 days. These results suggest that the common cattail may be a good candidate for incorporation into a phytoremediation scheme for metalaxyl and simazine.