title: Use-exposure relationships of pesticides for aquatic risk assessment.
abstract: Field-scale environmental models have been widely used in aquatic exposure assessments of pesticides. Those models usually require a large set of input parameters and separate simulations for each pesticide in evaluation. In this study, a simple use-exposure relationship is developed based on regression analysis of stochastic simulation results generated from the Pesticide Root-Zone Model (PRZM). The developed mathematical relationship estimates edge-of-field peak concentrations of pesticides from aerobic soil metabolism half-life (AERO), organic carbon-normalized soil sorption coefficient (KOC), and application rate (RATE). In a case study of California crop scenarios, the relationships explained 90-95% of the variances in the peak concentrations of dissolved pesticides as predicted by PRZM simulations for a 30-year period. KOC was identified as the governing parameter in determining the relative magnitudes of pesticide exposures in a given crop scenario. The results of model application also indicated that the effects of chemical fate processes such as partitioning and degradation on pesticide exposure were similar among crop scenarios, while the cross-scenario variations were mainly associated with the landscape characteristics, such as organic carbon contents and curve numbers. With a minimum set of input data, the use-exposure relationships proposed in this study could be used in screening procedures for potential water quality impacts from the off-site movement of pesticides.
authors.affiliation: Department of Pesticide Regulation, California Environmental Protection Agency, Sacramento, California, United States of America. yluo@cdpr.ca.gov
authors.forename: Yuzhou
authors.initials: Y
authors.lastname: Luo
authors.forename: Frank
authors.initials: F
authors.lastname: Spurlock
authors.forename: Xin
authors.initials: X
authors.lastname: Deng
authors.forename: Sheryl
authors.initials: S
authors.lastname: Gill
authors.forename: Kean
authors.initials: K
authors.lastname: Goh
mesh_terms: D059001:Aquatic Organisms / Q000187:drug effects*; D055598:Chemical Phenomena; D018556:Crops, Agricultural / Q000009:adverse effects; D003657:Decision Making; D004781:Environmental Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D004785:Environmental Pollutants / Q000737:chemistry / Q000633:toxicity*; D019015:Geologic Sediments / Q000737:chemistry; D016014:Linear Models; D008962:Models, Theoretical; D010575:Pesticides / Q000737:chemistry / Q000633:toxicity*; D018570:Risk Assessment; D012987:Soil
chemical_list: D004785:Environmental Pollutants; D010575:Pesticides; D012987:Soil