|Smith Jr, Sammie|
Submitted to: International Journal of Ecology and Environmental Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2003
Publication Date: December 15, 2003
Citation: Cooper, C.M., Smith Jr, S., Moore, M.T. 2003. Surface water, ground water and sediment quality in three oxbow lake watersheds in the Mississippi Delta agricultural region: Pesticides. International Journal of Ecology and Environmental Sciences. 29:171-184. Interpretive Summary: Purity of water has been, is currently, and will be an issue with the American public. Threats and security of water supplies, has led the American public to a heightened awareness of water quality. We conducted a study on potential pesticide contamination from agricultural fields in surface water, lake sediment, and shallow groundwater in an intensively cultivated agricultural region. We found that contamination of shallow groundwater was not a cause for concern. Lake sediments did not present a major problem either because most residual insecticides have been effectively sealed off from surface water by newer sediments. Pesticides in surface water seldom exceeded drinking water standards, but they did present cause for concern. However, concentrations that we measured can be drastically reduced by a combination of on-field and edge of field best management practices. This information is valuable to watershed planners (state and USDA-NRCS), state and federal water quality regulators, farmers and growers who must deal w/ potential contamination, and the American public.
Technical Abstract: Abstract: We measured residual and current use pesticides in shallow groundwater, surface water, and lake sediment in three oxbow lakes and their watersheds in the intensively cultivated alluvial plain of the Mississippi River, USA. The three year study focused on providing knowledge of pesticide movement and concentrations from intensive agricultural production and evaluating the degree of contaminant deposition and persistence in oxbow sediments. Penetration of insecticides into shallow groundwater did not represent a hazard. Herbicides and insecticides were found in surface water as a result of rainfall related runoff. Atrazine had the largest number of detections (28% of lake water samples). Sediment cores taken for pesticide analysis were also viewed by age each in each lake. Residual organochlorines dominated the pesticide sediment profile. DDT and its metabolites were the only compounds which permeated sediments at all sites. Sediments deposited in the 1960s and 1970s which contained higher concentrations of DDT have been effectively sealed by more recent material so that the sink of contaminant is unavailable to the water column. Controlled release of pyrethroid insecticides in a forested wetland showed that the wetland was totally effective in neutralizing the pyrethroids before they reached lake surface water. Pesticides seldom exceeded drinking water standards. Acute toxicity concerns lessen as more conservation measures are installed on and off fields. Additionally, DDT metabolites continue to slowly degrade.