title: Does mechanistic modeling of filter strip pesticide mass balance and degradation processes affect environmental exposure assessments?
abstract: Vegetative filter strips (VFS) are a widely adopted practice for limiting pesticide transport from adjacent fields to receiving waterbodies. The efficacy of VFS depends on site-specific input factors. To elucidate the complex and non-linear relationships among these factors requires a process-based modeling framework. Previous research proposed linking existing higher-tier environmental exposure models with a well-tested VFS model (VFSMOD). However, the framework assumed pesticide mass stored in the VFS was not available for transport in subsequent storm events. A new pesticide mass balance component was developed to estimate surface pesticide residue trapped in the VFS and its degradation between consecutive runoff events. The influence and necessity of the updated framework on acute and chronic estimated environmental concentrations (EECs) and percent reductions in EECs were investigated across three, 30-year U.S. EPA scenarios: Illinois corn, California tomato, and Oregon wheat. The updated framework with degradation predicted higher EECs than the existing framework without degradation for scenarios with greater sediment transport, longer VFS lengths, and highly sorbing and persistent pesticides. Global sensitivity analysis (GSA) assessed the relative importance of mass balance and degradation processes in the context of other input factors like VFS length (VL), organic-carbon sorption coefficient (Koc), and soil and water half-lives. Considering VFS pesticide residue and degradation was not important if single, large runoff events controlled transport, as is typical for higher percentiles considered in exposure assessments. Degradation processes become more important when considering percent reductions in acute or chronic EECs, especially under scenarios with lower pesticide losses.
authors.affiliation: Hydrology & Water Quality, Agricultural & Biological Engineering, University of Florida, 287 Frazier Rogers Hall, P.O. Box 110570, Gainesville, FL 32611-0570, United States. Electronic address: carpena@ufl.edu.
authors.forename: Rafael
authors.initials: R
authors.lastname: Muñoz-Carpena
authors.affiliation: Waterborne Environmental, Inc., 897-B Harrison Street S.E., Leesburg, VA 20175, United States. Electronic address: rittera@waterborne-env.com.
authors.forename: Amy
authors.initials: A
authors.lastname: Ritter
authors.affiliation: Biosystems and Agricultural Engineering, Oklahoma State University, 120 Agricultural Hall, Stillwater, OK 74078, United States; Oklahoma Water Resources Center, Oklahoma State University, 245 Agricultural Hall, Stillwater, OK 74078, United States. Electronic address: garey.fox@okstate.edu.
authors.forename: Garey A
authors.initials: GA
authors.lastname: Fox
authors.affiliation: Environmental Safety, Bayer CropScience LP, Environmental Exposure Assessment, 2 T.W. Alexander Drive, Research Triangle Park, NC 27709, United States. Electronic address: oscar.perez-ovilla@bayer.com.
authors.forename: Oscar
authors.initials: O
authors.lastname: Perez-Ovilla
mesh_terms: D003247:Conservation of Natural Resources / Q000379:methods*; D004781:Environmental Exposure / Q000032:analysis*; D004785:Environmental Pollutants / Q000737:chemistry*; D008962:Models, Theoretical; D010573:Pesticide Residues / Q000737:chemistry*; D012987:Soil / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D010573:Pesticide Residues; D012987:Soil
keywords: Degradation; Estimated environmental concentration (EEC); Global sensitivity analysis; Morris method; Pesticides; Vegetative filter strips