Location: Water Quality and Ecology ResearchTitle: Mitigation of atrazine, S-metolachlor, and diazinon using common aquatic emergent vegetation) Author
Submitted to: Journal of Environmental Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2016
Publication Date: N/A
Citation: N/A Interpretive Summary: Agricultural runoff containing pesticides can damage fish, invertebrates, and other aquatic organisms following storm or irrigation runoff events. One proposed management practice is the use of vegetated agricultural drainage ditches to intercept agricultural runoff and filter out the pesticides. Three common types of plants found in ditches were evaluated to see how well they could reduce the amount of pesticides travelling in storm water. Two plants-- rice cutgrass and cattails--were most effective at decreasing concentrations and loads of the two herbicides and one insecticide tested. Bur-reeds were less effective, but still valuable in reducing the amount of pesticides from water. These results are important for conservation planners and farmers interested in reducing the amount of pesticides leaving agricultural fields following runoff.
Technical Abstract: Based on current population rates, by the year 2050, the population of the United States will reach over 418 million, while the global population will reach 9.6 billion. To continue providing safe food and fiber for this population increase, agriculture must balance the mixture of natural resources and pesticide usage. Problems arise, however, when adverse weather conditions cause field runoff to be transported to surrounding aquatic receiving systems. Vegetated systems such as drainage ditches, constructed wetlands, and filter strips have been proposed as management practices to alleviate pesticide runoff. Twelve experimental mesocosms (1.3 x 0.71 x 0.61 m) were each filled with sediment and planted with a monoculture of one of three obligate wetland plant species [Typha latifolia (broad-leaf cattail), Leersia oryzoides (cutgrass), and Sparganium americanum (American bur-reed)]. Each plant species was represented by three replicate mesocosms. Additionally, three mesocosms remained unvegetated to serve as controls. All mesocosms were amended with 9.2±0.8 µg L-1, 12±0.4 µg L-1, and 3.1±0.2 µg L-1 of atrazine, metolachlor, and diazinon, respectively, over a 4 h hydraulic retention time to simulate storm runoff. Following the 4 h amendment, non-amended water was flushed through mesocosms for an additional 4 h. Outflow water samples were taken hourly from pre-amendment through 8 h, and again at 12, 24, 48, 72, and 168 h post-amendment. L. oryzoides and T. latifolia had mean atrazine, metolachlor, and diazinon retentions from 51-55% for the first 4 h of the experiment. Aside from S. americanum and atrazine (25% retention), unvegetated controls had the lowest pesticide retention (17-28%) of all compared mesocosms. While native aquatic vegetation shows promise for mitigation of pesticide runoff, further studies increasing the hydraulic retention time for improved efficiency should be examined.