Paper No. J05060 of the Journal of the American Water Resources Association (JAWRA).Discussions are open until February 1, 2008
Pesticide and Transformation Product Detections and Age-Dating Relations from Till and Sand Deposits1
Version of Record online: 28 JUN 2007
JAWRA Journal of the American Water Resources Association
Volume 43, Issue 4, pages 911–922, August 2007
How to Cite
Warner, K. L. and Morrow, W. S. (2007), Pesticide and Transformation Product Detections and Age-Dating Relations from Till and Sand Deposits. JAWRA Journal of the American Water Resources Association, 43: 911–922. doi: 10.1111/j.1752-1688.2007.00067.x
- Issue online: 28 JUN 2007
- Version of Record online: 28 JUN 2007
- Received May 3, 2005; accepted October 26, 2006.
- ground water hydrology;
- transformation product;
- age dating;
- glacial deposits
Abstract: Pesticide and transformation product concentrations and frequencies in ground water from areas of similar crop and pesticide applications may vary substantially with differing lithologies. Pesticide analysis data for atrazine, metolachlor, alachlor, acetochlor, and cyanazine and their pesticide transformation products were collected at 69 monitoring wells in Illinois and northern Indiana to document occurrence of pesticides and their transformation products in two agricultural areas of differing lithologies, till, and sand. The till is primarily tile drained and has preferential fractured flow, whereas the sand primarily has surface water drainage and primary porosity flow. Transformation products represent most of the agricultural pesticides in ground water regardless of aquifer material – till or sand. Transformation products were detected more frequently than parent pesticides in both the till and sand, with metolachlor ethane sulfonic acid being most frequently detected. Estimated ground-water recharge dates for the sand were based on chlorofluorocarbon analyses. These age-dating data indicate that ground water recharged prior to 1990 is more likely to have a detection of a pesticide or pesticide transformation product. Detections were twice as frequent in ground water recharged prior to 1990 (82%) than in ground water recharged on or after 1990 (33%). The highest concentrations of atrazine, alachlor, metolachlor, and their transformation products, also were detected in samples from ground water recharged prior to 1990. These age/pesticide detection relations are opposite of what would normally be expected, and may be the result of preferential flow and/or ground-water mixing between aquifers and aquitards as evident by the detection of acetochlor transformation products in samples with estimated ground-water ages predating initial pesticide application.