Hydrologist, U.S. Geological Survey, 5957 Lakeside Blvd., Indianapolis, Indiana 46278 (E-Mail: email@example.com).
SAMPLING STRATEGIES FOR ESTIMATING ACUTE AND CHRONIC EXPOSURES OF PESTICIDES IN STREAMS†
Article first published online: 8 JUN 2007
JAWRA Journal of the American Water Resources Association
Volume 40, Issue 2, pages 485–502, April 2004
How to Cite
Crawford, C. G. (2004), SAMPLING STRATEGIES FOR ESTIMATING ACUTE AND CHRONIC EXPOSURES OF PESTICIDES IN STREAMS. JAWRA Journal of the American Water Resources Association, 40: 485–502. doi: 10.1111/j.1752-1688.2004.tb01045.x
Paper No. 03097 of the Journal of the American Water Resources Association (JAWRA) (Copyright © 2004). Discussions are open until October 1, 2004.
- Issue published online: 8 JUN 2007
- Article first published online: 8 JUN 2007
- agricultural chemicals;
- Monte Carlo method;
- risk assessment;
- statistical analysis;
- sampling design;
- water sampling;
- water quality
ABSTRACT: The Food Quality Protection Act of 1996 requires that human exposure to pesticides through drinking water be considered when establishing pesticide tolerances in food. Several systematic and seasonally weighted systematic sampling strategies for estimating pesticide concentrations in surface water were evaluated through Monte Carlo simulation, using intensive datasets from four sites in northwestern Ohio. The number of samples for the strategies ranged from 4 to 120 per year. Sampling strategies with a minimal sampling frequency outside the growing season can be used for estimating time weighted mean and percentile concentrations of pesticides with little loss of accuracy and precision, compared to strategies with the same sampling frequency year round. Less frequent sampling strategies can be used at large sites. A sampling frequency of 10 times monthly during the pesticide runoff period at a 90 km2 basin and four times monthly at a 16,400 km2 basin provided estimates of the time weighted mean, 90th, 95th, and 99th percentile concentrations that fell within 50 percent of the true value virtually all of the time. By taking into account basin size and the periodic nature of pesticide runoff, costs of obtaining estimates of time weighted mean and percentile pesticide concentrations can be minimized.