Western Kentucky University
Atmospheric Transport of the Herbicide Atrazine in South Central Kentucky
Institution
Western Kentucky University
Faculty Advisor/ Mentor
Chris Grove
Abstract
Atrazine (2-chloro-4-ethylamine-6-isopropylamino-S-triazine) is a triazine-class herbicide that is used widely in Kentucky to control broad-leaf weeds in corn cultivation. It is a Restricted Use Pesticide, and since 1994 has been the subject of a Special Review by the US Environmental Protection Agency. The Maximum Contaminant Level (MCL) for atrazine in treated drinking water is three parts per billion (ppb), and recently attention has been drawn to potentially serious developmental impacts among amphibians exposed to low concentrations. Starting in April, 2003, atrazine concentrations in rainfall were monitored throughout south central Kentucky. Samples were collected using glass funnels that directed rainfall into glass VOC bottles, and analyzed using Quantitative Immunoassy. Of 199 samples collected between April 17 and August 29, 180 (90%) were positive (>0.05 ppb). 43 samples exceeded 1 ppb, six were over 2 ppb, and two samples over the MCL of 3 ppb. The mean concentration overall was 0.5 ppb. One sample of condensed fog and one of dew had concentrations of 1.7 and 1.8 ppb, respectively. Four samples taken sequentially through one storm in April showed a clear atmospheric scavenging effect: the first sample of over 3 ppb was followed by three that were all an order of magnitude lower. This same effect resulted in high concentrations for trace rainfalls. Samples collected during the spring herbicide application season (assumed to end on May 31) had a mean (0.70 ppb) almost three times higher than later samples (0.25 ppb), and almost 80% of the non-detects also occurred after this date.
Atmospheric Transport of the Herbicide Atrazine in South Central Kentucky
Atrazine (2-chloro-4-ethylamine-6-isopropylamino-S-triazine) is a triazine-class herbicide that is used widely in Kentucky to control broad-leaf weeds in corn cultivation. It is a Restricted Use Pesticide, and since 1994 has been the subject of a Special Review by the US Environmental Protection Agency. The Maximum Contaminant Level (MCL) for atrazine in treated drinking water is three parts per billion (ppb), and recently attention has been drawn to potentially serious developmental impacts among amphibians exposed to low concentrations. Starting in April, 2003, atrazine concentrations in rainfall were monitored throughout south central Kentucky. Samples were collected using glass funnels that directed rainfall into glass VOC bottles, and analyzed using Quantitative Immunoassy. Of 199 samples collected between April 17 and August 29, 180 (90%) were positive (>0.05 ppb). 43 samples exceeded 1 ppb, six were over 2 ppb, and two samples over the MCL of 3 ppb. The mean concentration overall was 0.5 ppb. One sample of condensed fog and one of dew had concentrations of 1.7 and 1.8 ppb, respectively. Four samples taken sequentially through one storm in April showed a clear atmospheric scavenging effect: the first sample of over 3 ppb was followed by three that were all an order of magnitude lower. This same effect resulted in high concentrations for trace rainfalls. Samples collected during the spring herbicide application season (assumed to end on May 31) had a mean (0.70 ppb) almost three times higher than later samples (0.25 ppb), and almost 80% of the non-detects also occurred after this date.