Pesticide Transport in Subsurface and Surface Water Systems

EPA Grant Number: R825433C052
Subproject: this is subproject number 052 , established and managed by the Center Director under grant R825433
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EERC - Center for Ecological Health Research (Cal Davis)
Center Director: Rolston, Dennis E.
Title: Pesticide Transport in Subsurface and Surface Water Systems
Investigators: Marino, Miguel
Institution: University of California - Davis
EPA Project Officer: Levinson, Barbara
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992) RFA Text |  Recipients Lists
Research Category: Center for Ecological Health Research , Targeted Research


This project seeks to investigate the fate of non-point source (NPS) pesticides in subsurface and surface water by developing a systematic procedure and practical analytical tool for evaluation of the leaching potential of pesticide residues to groundwater and the potential threat of pesticide emissions to adjacent rivers/streams.


Pesticide leaching leads to contamination of subsurface water systems. Due to pesticide loading from surface runoff, erosion, and groundwater discharge to an adjacent river/stream, the related surface water system may also be polluted. Pesticide fate and transport are primarily controlled by subsurface and surface settings as well as agricultural practices, and are influenced by a set of physical, chemical, and biological processes, such as infiltration, evapotranspiration, crop-root uptake, advection, dispersion, sorption, decay, volatilization, etc. This research is aimed to characterize these processes, to quantify the spatial and temporal distribution of pesticide residues, to evaluate their potential adverse impact on water resources, and eventually to identify feasible management practices by using modeling techniques. This study would subsequently provide input for ecological models that investigate the negative effects of pesticide residues on the aquatic organisms in rivers/streams.

Currently, an integrated pesticide transport model with compartmentalized structure has been developed. Although the model is able to quantify pesticide pollution to streams/rivers and aquifers, the focus of the modeling is on simulating three-phase (dissolved, adsorbed, and vapor) pesticide migrations along the unsaturated soil profile, which is further categorized into the surface zone, crop root zone, and vadose zone. A thin surface zone is defined so as to facilitate the modeling of the interaction between overland flow and soil solution, and corresponding processes (runoff and erosion). Linear-equilibrium sorption and first-order degradation are assumed in the model. The SCS method is applied to estimate the runoff; the Modified Universal Soil Loss Equation (MUSLE) is used to calculate the eroded sediment yield; and the film theory is employed in the computation of volatilization. The crop-root uptake of pesticide residues in the root zone is estimated by using the water uptake rate of crop and transpiration stream concentration factor. Compartmental models describing advection, dispersion, and degradation of pesticide residues in aquifer and rivers have been also developed.

Contamination resulting from application of organophosphate (OP) insecticides to orchards has been a particular concern in the Central Valley of California. Coincidence of the dormant applications with the seasonal rainfall events provides a high potential for the pesticides to wash off target fields into the nearby canals, streams/rivers with surface runoff and erosion. To address this crucial issue and test the integrated model, we selected diazinon (one of the most frequently detected OP insecticides) and the Wadsworth Canal Basin (one of the most heavily applied areas) as our target pesticide and application site in the Sacramento River watershed. The model provided the diazinon exposure levels in the surface water, spatial and temporal distributions in soils, and potential loading to the underlying groundwater. Good agreement between the simulated and measured concentrations was observed. The modeling results indicate that diazinon frequently exceeds criteria for aquatic life during the dormant season. Furthermore, diazinon concentrations may even exceed the human-health criterion although the high peak pulses last a very short time. It is demonstrated that the amount and combined timing of pesticide application and rainfall dominate its levels in both subsurface and surface waters. It is also observed that diazinon residues are only concentrated within the shallow soil and no obvious threat to the groundwater can be inferred in the selected area.

Expected Results:

Future work will focus on the improvement of the integrated model and application of the model in the San Joaquin River watershed. Expandability of the modeling system will be emphasized. Special efforts will be made for simulating pesticide transport in groundwater. Fresno and/or Oristimba Creek basin will be selected for our case studies. The main purpose of the Fresno work is to characterize the vulnerability of the subsurface environment to simazine, one of the most frequently detected pesticides in groundwater of that area. Diazinon contamination in the surface water, induced by dormant season application, will be investigated in the study for the Oristimba Creek basin. To minimize the adverse impacts of pesticide residues on the water-associated ecosystem, a set of management schemes will be analyzed and the improved management practices will be identified.

Supplemental Keywords:

Watershed, fate and transport, modeling, ecosystem stress, pesticides, Diazinon, Sacramento River, hydrologic model, California, groundwater., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Aquatic Ecosystems & Estuarine Research, Aquatic Ecosystem, Fate & Transport, Environmental Microbiology, Monitoring/Modeling, Terrestrial Ecosystems, Biochemistry, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Watersheds, fate and transport, aquatic, watershed management, ambient particle properties, ecosystem assessment, Sacramento River, sediment transport, pesticides, restoration strategies, modeling, watershed influences, hydrology, wetland restoration, integrated watershed model, chemical kinetics, aquatic ecosystems, environmental stress, source load modeling, watershed sustainablility, material transport, groundwater contamination, ecosystem stress, ecology assessment models, ecological impact, agrochemicals, vadose zone, ecological research, watershed restoration

Progress and Final Reports:

1999 Progress Report
2000 Progress Report
Final Report

Main Center Abstract and Reports:

R825433    EERC - Center for Ecological Health Research (Cal Davis)

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825433C001 Potential for Long-Term Degradation of Wetland Water Quality Due to Natural Discharge of Polluted Groundwater
R825433C002 Sacramento River Watershed
R825433C003 Endocrine Disruption in Fish and Birds
R825433C004 Biomarkers of Exposure and Deleterious Effect: A Laboratory and Field Investigation
R825433C005 Fish Developmental Toxicity/Recruitment
R825433C006 Resolving Multiple Stressors by Biochemical Indicator Patterns and their Linkages to Adverse Effects on Benthic Invertebrate Patterns
R825433C007 Environmental Chemistry of Bioavailability in Sediments and Water Column
R825433C008 Reproduction of Birds and mammals in a terrestrial-aquatic interface
R825433C009 Modeling Ecosystems Under Combined Stress
R825433C010 Mercury Uptake by Fish
R825433C011 Clear Lake Watershed
R825433C012 The Role of Fishes as Transporters of Mercury
R825433C013 Wetlands Restoration
R825433C014 Wildlife Bioaccumulation and Effects
R825433C015 Microbiology of Mercury Methylation in Sediments
R825433C016 Hg and Fe Biogeochemistry
R825433C017 Water Motions and Material Transport
R825433C018 Economic Impacts of Multiple Stresses
R825433C019 The History of Anthropogenic Effects
R825433C020 Wetland Restoration
R825433C021 Sierra Nevada Watershed Project
R825433C022 Regional Transport of Air Pollutants and Exposure of Sierra Nevada Forests to Ozone
R825433C023 Biomarkers of Ozone Damage to Sierra Nevada Vegetation
R825433C024 Effects of Air Pollution on Water Quality: Emission of MTBE and Other Pollutants From Motorized Watercraft
R825433C025 Regional Movement of Toxics
R825433C026 Effect of Photochemical Reactions in Fog Drops and Aerosol Particles on the Fate of Atmospheric Chemicals in the Central Valley
R825433C027 Source Load Modeling for Sediment in Mountainous Watersheds
R825433C028 Stress of Increased Sediment Loading on Lake and Stream Function
R825433C029 Watershed Response to Natural and Anthropogenic Stress: Lake Tahoe Nutrient Budget
R825433C030 Mercury Distribution and Cycling in Sierra Nevada Waterbodies
R825433C031 Pre-contact Forest Structure
R825433C032 Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
R825433C033 Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
R825433C034 Regional Hydrogeology and Contaminant Transport in a Sierra Nevada Ecosystem
R825433C035 Border Rivers Watershed
R825433C036 Toxicity Studies
R825433C037 Watershed Assessment
R825433C038 Microbiological Processes in Sediments
R825433C039 Analytical and Biomarkers Core
R825433C040 Organic Analysis
R825433C041 Inorganic Analysis
R825433C042 Immunoassay and Serum Markers
R825433C043 Sensitive Biomarkers to Detect Biochemical Changes Indicating Multiple Stresses Including Chemically Induced Stresses
R825433C044 Molecular, Cellular and Animal Biomarkers of Exposure and Effect
R825433C045 Microbial Community Assays
R825433C046 Cumulative and Integrative Biochemical Indicators
R825433C047 Mercury and Iron Biogeochemistry
R825433C048 Transport and Fate Core
R825433C049 Role of Hydrogeologic Processes in Alpine Ecosystem Health
R825433C050 Regional Hydrologic Modeling With Emphasis on Watershed-Scale Environmental Stresses
R825433C051 Development of Pollutant Fate and Transport Models for Use in Terrestrial Ecosystem Exposure Assessment
R825433C052 Pesticide Transport in Subsurface and Surface Water Systems
R825433C053 Currents in Clear Lake
R825433C054 Data Integration and Decision Support Core
R825433C055 Spatial Patterns and Biodiversity
R825433C056 Modeling Transport in Aquatic Systems
R825433C057 Spatial and Temporal Trends in Water Quality
R825433C058 Time Series Analysis and Modeling Ecological Risk
R825433C059 WWW/Outreach
R825433C060 Economic Effects of Multiple Stresses
R825433C061 Effects of Nutrients on Algal Growth
R825433C062 Nutrient Loading
R825433C063 Subalpine Wetlands as Early Indicators of Ecosystem Stress
R825433C064 Chlorinated Hydrocarbons
R825433C065 Sierra Ozone Studies
R825433C066 Assessment of Multiple Stresses on Soil Microbial Communities
R825433C067 Terrestrial - Agriculture
R825433C069 Molecular Epidemiology Core
R825433C070 Serum Markers of Environmental Stress
R825433C071 Development of Sensitive Biomarkers Based on Chemically Induced Changes in Expressions of Oncogenes
R825433C072 Molecular Monitoring of Microbial Populations
R825433C073 Aquatic - Rivers and Estuaries
R825433C074 Border Rivers - Toxicity Studies