UNDERSTANDING AND PREDICTING THE IMPACT OF AGRICULTURE ON THE ENVIRONMENTAL INTEGRITY OF MANAGED WATERSHEDS
Location: Water Quality and Ecology Research
Title: Effects of a simulated agricultural runoff event on sediment toxicity in a managed backwater wetland
Submitted to: Water, Air, and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 25, 2012
Publication Date: September 17, 2012
Citation: Lizotte Jr, R.E., Shields Jr, F.D., Testa III, S. 2012. Effects of a simulated agricultural runoff event on sediment toxicity in a managed backwater wetland. Water, Air, and Soil Pollution. 223:5375-5389.
Interpretive Summary: Wetlands are sometimes used to lessen possible ecological impacts from agriculture. As a result, we examined the pesticide effects on an aquatic invertebrate animal, Hyalella azteca, in sediment from a managed wetland after an artificially produced agricultural runoff event. We examined the ability of this managed wetland to decrease the ecological effects of three pesticides, atrazine, S-metolachlor, and permethrin, occurring in wetland sediment on this aquatic invertebrate animal. The study showed that the managed wetland was effective at decreasing the effects of pesticides moving into sediment after an agricultural runoff on aquatic animals during average rainfall events. Our results are of interest to regulatory and other agencies and the pesticide industry by providing additional information to improve and sustain river, stream and lake sediment quality and overall environmental quality using constructed wetlands as an effective conservation practice.
permethrin (both cis and trans isomers), on 10-day sediment toxicity to Hyalella azteca in a managed natural backwater wetland after a simulated agricultural runoff event. Sediment samples were collected at 10, 40, 100, 300, and 500 m from inflow 13 days prior to amendment and 1, 5, 12, 22, and 36 days post-amendment. Atrazine and S-metolachlor were detected throughout the wetland, and permethrin was detected up to 300 m from inflow. H. azteca 10-day survival varied spatially and temporally up to 100 m from inflow. Animal growth, independent of survival, was reduced 40 m and 100 m from inflow on day 36, showing continued sediment toxicity up to 100 m from inflow more than 1 month after amendment. Animal survival and growth were unaffected at 300 and 500 m from inflow throughout the study period. Correlations of pesticide concentrations and H. azteca responses indicated observed sediment toxicity was from permethrin. Study results indicate that natural backwater wetlands can be managed to ameliorate pesticide mixture 10-day sediment toxicity to H. azteca within 300 m of inflow and smaller wetlands (=100 m) may require several months of effluent retention to mitigate effects.