ARS | Publication request: Current- and past-use pesticide prevalence in drainage ditches in the Lower Mississippi Alluvial Valley

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 27, 2011
Publication Date: January 5, 2012
Repository URL: http://handle.nal.usda.gov/10113/54428
Citation: Kroger, R., Moore, M.T., Brandt, J.R. 2012. Current- and past-use pesticide prevalence in drainage ditches in the Lower Mississippi Alluvial Valley. Pest Management Science. 68:303-312.

Interpretive Summary: Drainage ditches are important agricultural landscape features that transport excess water from crops into receiving aquatic systems. A study was conducted collecting samples from agricultural ditches in four states and measuring the presence of current and past-use pesticides. Although ditches have the ability to reduce the amount of pesticides associated with runoff water before they enter rivers, lakes, or streams, little is known about the relative persistence of these pesticides in natural ditch settings. Samples were collected seasonally to determine if pesticides were a potential threat to downstream aquatic systems. Most pesticides analyzed in this study were below detection limits, although some organochlorine pesticides (e.g. DDT) still were present at detectable concentrations.

Technical Abstract: BACKGROUND: Pesticide use is ubiquitous in agriculture and often results in applied pesticides entering adjacent aquatic systems. This study seasonally analyzed a suite of 17 current and past-use pesticides in both drainage waters and sediments to evaluate the prevalence of pesticides in drainage ditches across the Lower Mississippi Alluvial Valley (LMAV). RESULTS: There were significantly higher detection percentages and concentrations (P<0.05) between current use pesticides and past-use pesticides. Sediment pesticide concentrations were an order of magnitude higher (150–300 µg kg-1) than water samples (6–14 µg L-1), though there were no correlations (0.0005 > r2 < 0.01) between pesticide Koc values and sediment/water pesticide concentrations. There were no correlations between pesticide prevalence (occurrence) and season (r2<0.03). Overall, 36±4.5% of all samples analyzed for current and past-use pesticides were non-detects. p’p-DDT was only detected in 19.9% of all drainage sediments sampled. CONCLUSION: Overall there was a high percentage (87%) of sediment and water samples that did not contain detectable concentrations above the lower limit of analytical detection. This lack of pesticide prevalence highlights the improved conditions in aquatic systems adjacent to agriculture and a potential decrease in toxicity associated with pesticides in agricultural landscapes in the LMAV.