|Smith Jr, Sammie|
|Shields Jr, Fletcher|
Submitted to: International Conference on Diffuse Pollution
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2002
Publication Date: 9/30/2002
Citation: Moore, M.T., Cooper, C.M., Smith Jr, S., Bennett, E.R., Schulz, R., Farris, J.L., Shields Jr, F.D. 2002. Influence of vegetation in mitigation of methyl parathion runoff. Proceedings of the 6th International Conference on Diffuse Pollution. p. 111-118. Interpretive Summary: Wetland areas serve as filters to remove potential contaminants such as pesticides and excessive nutrients that may damage rivers, lakes, and streams surrounding agricultural land. Many wetlands were destroyed in order to make room for more agricultural production acreage. When these systems were removed, the environment lost a natural system for filtering potential pollutants. This research examined how beneficial these systems, and those of vegetated agricultural drainage ditches, can be in removing pesticides from agricultural storm water runoff. Results indicated that when vegetation is present in these types of systems (wetlands or drainage ditches), pesticides have a greater chance of binding to the vegetation rather than being carried further down into the lakes, rivers, and streams where they could potentially damage the fish and other aquatic life in these systems. This research also provided estimations for vegetated ditch and wetland system lengths needed to bind potentially leached pesticides.
Technical Abstract: Many wetlands in the United States and elsewhere were drained in the early 20th century (with heavy losses in the 1960s and 1970s) to allow for increased agricultural production acreage. Along with this loss of wetlands came a concomitant loss of water quality enhancement by these former wetland areas. The result was an increase in downstream contamination from agricultural storm runoff. Constructed wetlands play an important role as an agricultural best management practice for water quality improvement of storm runoff. A pesticide runoff event was simulated using two 10 m x 50 m constructed wetlands (one non-vegetated; one vegetated with Juncus effuses) to evaluate the fate of methyl parathion. Water, sediment, and plant samples were collected at five sites downstream of the inflow for a period of approximately 120 days. Results from the non-vegetated wetland cells illustrated that methyl parathion was detected in water throughout the entire system (50 m) 30 minutes post-exposure and was still detected after 10 days. In the vegetated wetland, methyl parathion was detected 20 m from the inflow 30 minutes post-exposure, while after 10 days it was only detected at 10 m. In addition to this, methyl parathion was detected only in the semipermeable membrane devices (SPMDs) deployed in the non-vegetated wetland cells, which further suggests that detectable levels were not present near the outflow of the vegetated wetland. These results demonstrate the importance of vegetation as sorption sites for pesticide mitigation.