ENVR 105 |
| Surface waters are often contaminated with non-point source organic compounds originating from agricultural runoff. The environmental fate of these compounds is generally unknown, but many of them can be degraded by both direct and indirect photolysis. In this study the photofate of metolachlor was investigated in wetland surface water containing nitrate and dissolved organic matter (DOM). Both substances are known photosensitizers capable of generating reactive oxygen species (ROS) that can degrade metolachlor. Nitrate becomes the dominant photosensitizer in spring and summer after application of fertilizers to farmland, leading to high NO3- levels (exceeding 1 mM) in runoff and wetland waters. During other times of the year, nitrate levels drop to <100 μM, making DOM the dominant photosensitizer initiating metolachlor degradation. To date our studies have shown that ROS generated by these sensitizers (predominantly the hydroxyl radical) is responsible for much of the observed photodegradation of metolachlor in wetland surface waters. |
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Environmental Contaminants: Low-Level and Complex Mixtures
1:30 PM-4:50 PM, Wednesday, August 22, 2007 Boston Park Plaza -- Stanbro Rm, Oral
Division of Environmental Chemistry |