Pesticide Mitigation Research Articles

Pesticides in stormwater runoff—A mini review

Recently, scientific interest has grown in harvesting and treating stormwater for potable water use, in order to combat the serious global water scarcity issue. In this context, pesticides have been identified as the key knowledge gap as far as reusing stormwater is concerned. This paper reviewed the presence of pesticides in stormwater runoff in both rural and urban areas. Specifically, the sources of pesticide contamination and possible pathways were investigated in this review. Influential factors affecting pesticides in stormwater runoff were critically identified as: 1) characteristics of precipitation, 2) properties of pesticide, 3) patterns of pesticides use, and 4) properties of application surface. The available pesticide mitigation strategies including best management practice (BMP), low impact development (LID), green infrastructure (GI) and sponge city (SC) were also included in this paper. In the future, large-scale multi-catchment studies that directly evaluate pesticide concentrations in both urban and rural stormwater runoff will be of great importance for the development of effective pesticides treatment approaches and stormwater harvesting strategies.

Comparison of empirical and mechanistic equations for vegetative filter strip pesticide mitigation in long-term environmental exposure assessments

Recent advances in mechanistic modeling of vegetated filter strips (VFS) have made it possible to incorporate VFS mitigation into environmental exposure assessments (EEAs). However, outside of fixed efficiency approaches, there are no widely adopted and standardized procedures for incorporating VFS quantitative mitigation into long-term, higher-tier EEAs. A source of hesitation involves the use of empirical equations for predicting pesticide trapping by the VFS. A recent study evaluated existing empirical equations and a mechanistic mass-balance approach using the most extensive field database available of VFS pesticide efficiency from single-event storms. That study concluded that an updated empirical equation (Sabbagh equation) and a mechanistic mass-balance approach performed reasonably well. The objective of this research was to study the effect of upscaling the VFS trapping equations from single events into long-term EEAs. The U.S. EPA Pesticide in Water Calculator (PWC) model linked with the Vegetative Filter Strip MODeling system (VFSMOD) long-term EEA modeling framework (30 yr) was updated to incorporate the alternative trapping equations and tested VFS mitigation results under contrasting agroecological settings with varying erosion/sediment transport conditions. Differences in both acute and chronic 90th percentile estimated environmental exposure concentrations (EECs) were relatively small when comparing predictions using the four pesticide trapping equations. A global sensitivity analysis (GSA) also indicated that selection of a specific trapping equation for predicting EECs was less important than other important input factors such as the VFS length and pesticide properties. However, in terms of the percent reductions in EECs, the choice of pesticide trapping equation was as important as the VFS length. This research builds upon the conclusion of previous single-event studies that the mechanistic mass-balance and refit Sabbagh empirical equation were both valid for EEAs. The mass balance approach represents a reasonable option for regulatory agencies that prefer mechanistic approaches.

Wetland hydrodynamics and mitigation of pesticides and their metabolites at pilot-scale

Constructed wetlands (CWs) are useful for reducing pesticide transfer from drainage into surface water, though little was known about the influence of hydrodynamics on their mitigation. We thus assessed the influence of design parameters (aspect ratio, water depth, flow rate) on hydraulic performance simultaneously to pesticide mitigation. We performed our work on four pesticides with contrasted properties: boscalid (BSC), cyproconazole (CYP), isoproturon (IPU) and dimethachlor (DMT), under three controlled flow-rate conditions (including no-flow) by using two pilots with contrasted designs (pond and ditch) over 62 days. Hydraulic performance and pesticide mitigation were less effective in a pond than in the ditch whatever the flow. Moreover, pesticide mitigation was more significant at low than at high flow rates for both pilots. At high flow rate, water transport is mainly governed by convection, but at low flow rates both water transport and mitigation are governed by hydrodynamic dispersion, inducing a longer contact time between pesticides and substrate due to longer hydraulic retention. Finally, BSC and CYP are better mitigated than DMT and IPU, even if they are also more strongly released during low flow rates. In addition, the mitigation of pesticides and some of their metabolites produced inside the pilots was almost complete during stagnation.

Leaf Composition of American Bur-Reed (Sparganium americanum Nutt.) to Determine Pesticide Mitigation Capability.

American bur-reed (Sparganium americanum Nutt.), a common aquatic plant in the middle and eastern United States and Canada, is often located in water-retaining drainage areas. The purpose of this study was to determine the leaf composition of S. americanum, paying attention to the cuticular waxes and the epidermis, and its ability to sorb pesticides. S. americanum leaves (n = 100) were collected in both early (June) and late (August) summer. Transverse sections of S. americanum were stained and studied with brightfield and fluorescence microscopy to estimate the structural and chemical nature of the leaf tissues cross sections. Mean total lipid content in early summer leaf samples (1.47 ± 0.83mgmL-1) was significantly greater (alpha 0.05) than late summer leaves (0.15 ± 0.36mgmL-1). In vitro analysis of epidermal peel permeability exposed to atrazine and malathion determined little to no sorption by the plant. Therefore, the structure of S. americanum leaves suggest this species does not have the capacity of sorbing these pesticides from runoff water.

Dynamics of chloroacetanilide herbicides in various types of mesocosm wetlands

Constructed wetlands (CWs) for pesticide mitigation from agricultural runoff became widespread in the last decade. However, comparison of different types of CWs at one location is missing. Therefore, site by site comparison of three different types (subsurface flow, surface flow and floating hydroponic root mat) of CWs treating four chloroacetanilide herbicides (acetochlor, s-metolachlor, metazachlor, dimethachlor) were carried out. All three planted systems are effective in removing the four herbicides with removal efficiency >92% after 9days. The metabolites ethane sulfonic acids (ESA) and oxanilic acids (OA) of the four herbicides peaked at 9days in the surface flow CWs with soil, but all the metabolites didn't peaked in the subsurface flow with gravel systems and the floating hydroponic root mat system after 21days. All the detected metabolites account about 20% of the mother compounds. There is no noticeable metabolites accumulation in the control system (no plants and no substrate), which indicate no microbial degradation taken place. Plant accumulation and soil adsorption are negligible for the removal of the four herbicides, which are <0.6%. In conclude, plants can enhance the removal of chloroacetanilide herbicides in all the CWs, and the floating hydroponic root mat is the most cost-efficient alternatives for chloroacetanilide herbicides removal due to the absence of substrate.

Multidisciplinary assessment of pesticide mitigation in soil amended with vermicomposted agroindustrial wastes

Soil organic amendment affects biotic and abiotic processes that control the fate of pesticides, but the treatment history of the soil is also relevant. These processes were assessed in a multidisciplinary study with the aim of optimizing pesticide mitigation in soils. Soil microcosms pre-treated (E2) or not with diuron (E1) were amended with either winery (W) or olive waste (O) vermicomposts. Herbicide dissipation followed a double first-order model in E1 microcosms, but a single first-order model in E2. Also, diuron persistence was longer in E1 than in E2 (E1-DT50>200 day−1, E2-DT50<16 day−1). The genetic structure of the bacterial community was modified by both diuron exposure and amendment. O-vermicompost increased enzymatic activities in both experiments, but diuron-degrading genetic potential (puhB) was quantified only in E2 microcosms in accordance with reduced diuron persistence. Therefore, O-vermicompost addition favoured the proliferation of diuron degraders, increasing the soil diuron-depuration capability.

Experiments in water-macrophyte systems to uncover the dynamics of pesticide mitigation processes in vegetated surface waters/streams.

Knowledge on the dynamics and the durability of the processes governing the mitigation of pesticide loads by aquatic vegetation in vegetated streams, which are characterized by dynamic discharge regimes and short chemical residence times, is scarce. In a static long-term experiment (48 h), the dissipation of five pesticides from the aqueous phase followed a biphasic pattern in the presence of aquatic macrophytes. A dynamic concentration decrease driven by sorption to the macrophytes ranged from 8.3 to 60.4% for isoproturon and bifenox, respectively, within the first 2 h of exposure. While the aqueous concentrations of imidacloprid, isoproturon, and tebufenozide remained constant thereafter, the continuous but decelerated concentration decrease of difenoconazole and bifenox in the water-macrophyte systems used here was assumed to be attributed to macrophyte-induced degradation processes. In addition, a semi-static short-term experiment was conducted, where macrophytes were transferred to uncontaminated medium after 2 h of exposure to simulate a transient pesticide peak. In the first part of the experiment, adsorption to macrophytes resulted in partitioning coefficients (logK D_Adsorp) ranging from 0.2 for imidacloprid to 2.2 for bifenox. One hour after the macrophytes were transferred to the uncontaminated medium, desorption of the compounds from the macrophytes resulted in a new phase equilibrium and K D_Desorp values of 1.46 for difenoconazole and 1.95 for bifenox were determined. A correlation analysis revealed the best match between the compound affinity to adsorb to macrophytes (expressed as K D_Adsorp) and their soil organic carbon-water partitioning coefficient (K OC) compared to their octanol-water partitioning coefficient (K OW) or a mathematically derived partitioning coefficient.

Influence of varying nutrient and pesticide mixtures on abatement efficiency using a vegetated free water surface constructed wetland mesocosm

The nutrient and pesticide abatement efficiency of varying mixtures was examined in a vegetated free water surface constructed wetland. Three different agricultural chemical pollutant mixture conditions were assessed: nutrients only (N and P); pesticides only (atrazine, S-metolachlor and permethrin); and a mixture of nutrients and pesticides. With nutrients only, 672 h nutrient mitigation of 77–91% total phosphorous (TP) and 74–98% total nitrogen (TN) was associated with distance from the injection point and rainfall, whereas with nutrient and pesticide mixtures, 672 h nutrient mitigation of 11–71% TP and 84–98% TN were associated with distance and time. With pesticides only, 672 h pesticide mitigation of 50–99% was associated with distance and time, whereas with nutrients and pesticide mixtures, 672 h pesticide mitigation of 48–99% was associated primarily with distance. Dissipation half-lives were 2–10 times greater for P and 1.5–5 times greater for N when pesticides were present. Pesticide dissipation half-lives showed no clear differences with or without nutrients. While vegetated free water surface constructed wetlands can be effective best management practice tools to trap and abate agricultural run-off during rainfall events, efficiencies can be affected by different types of complex pollutant mixtures and wetland design and implementation should accommodate varying efficiencies.

Mitigation of Two Insecticides by Wetland Plants: Feasibility Study for the Treatment of Agricultural Runoff in Suriname (South America)

In agricultural areas, pesticides can enter receiving waterbodies by means of agricultural runoff and pollute these systems. Constructed wetlands are capable of removing several pollutants including pesticides. Unfortunately, few studies are from South America, and therefore, information is urgently needed on pesticide mitigation in agricultural runoff by native plants. To this aim, an experimental setup of polypropylene tubs was used, which were planted with two types of native plants (Nymphaea amazonum and Eleocharis mutata). Mesocosms were exposed to low (10 μg/l) and high (30 μg/l) target concentrations of lambda-cyhalothrin, while for imidacloprid, a low (60 μg/l), high (180 μg/l), and an extra high (1,000 μg/l) dose, were applied using batch experiments of 2 weeks each. Removal efficiencies for lambda-cyhalothrin from the water phase showed 100 % removal at 72 h for both low and high target concentrations for N. amazonum mesocosms, while for E. mutata mesocosms, a 100 % removal was observed at 48 h for mesocosms exposed to low target concentrations and for high target concentrations at 72 h. For imidacloprid, a 100 % removal was observed for E. mutata and 86 % for N. amazonum mesocosms exposed to low target concentrations (60 μg/l) at 216 h. For the highest dose (1,000 μg/l), the removal efficiency was on average 72 % at 216 h for both types of mesocosms. Statistical two-way ANOVA analysis (α = 0.05) showed that the removal of lambda-cyhalothrin was independent of the dose applied and the plant type, while for imidacloprid, removal was dependent on the dose applied and independent of the plant type. After the experimental period, analyses of the plants and sediment showed that 48.5 % of the applied amount of lambda-cyhalothrin was detected in the sediment and 0.4 % in plant material (shoots and leaves), while the amount in roots was below the limit of detection for N. amazonum mesocosms. For E. mutata mesocosms, 44.6 % of lambda-cyhalothrin was detected in sediment and 0.5 % in roots. For N. amazonum mesocosms, 78.9 % of the applied amount of imidacloprid was retained in plants (plant material and roots) and 17.31 % in sediment, while for E. mutata mesocosms only 0.5 % of imidacloprid was detected in plant material and roots. In this experiment, the DT50 of lambda-cyhalothrin in the water phase of both types of mesocosms was on average 1 day, while for imidacloprid, this was calculated to be around 1–10 days. The results obtained provide necessary information for the construction of a field scale wetland capable of efficient removal of pesticides in agricultural runoff.

Regulation of diffuse pesticide pollution: Combining point source reduction and mitigation in stormwater wetland (Rouffach, France)

The economic crisis and increasingly stringent water quality requirements demand integrative approaches to reduce pesticide pollution in aquatic ecosystems and limit water treatment. In this study, environmental economists and wetland scientists joined forces to analyze the combination of different abatement measures to reduce pollution with more efficiency.Pesticide reduction directly at source (i.e., reduction of pesticide use), and combining pesticide source reduction with mitigation using a stormwater wetland to treat pesticide runoff are compared. The capacity of the buffer zone to reduce additional diffuse pollution with a given total abatement cost is evaluated, by placing emphasis on how the contribution of a buffer zone evolves according to the total cost. Fungicides were used as a representative class of synthetic pesticides widely used in vine growing, and more largely in conventional agriculture.Our results show that coupling reduction of pesticide source with the use of buffer zones collecting pesticide runoff can be economically advantageous. For a given total cost, the reduction of fungicide runoff is 90% greater when pesticide reduction at source is combined with pesticide mitigation by a stormwater wetland compared to the case of pesticide reduction at source only. However, the higher the total cost is, the more it is necessary to reduce pesticides at source and thus reduce pesticide mass transfer into aquatic systems.The results of this study is anticipated to be a starting point for considering cost and efficiency when combining different measures targeting pesticide mitigation in surface water, and in particular when using stormwater wetlands as a management practice.

The Landau Stream Mesocosm Facility: Pesticide Mitigation in Vegetated Flow-Through Streams

Vegetated treatment systems have the ability to reduce the risk of adverse effects of nonpoint source pesticide pollution in agricultural surface waters, however, flow-through systems have rarely been evaluated. Peak concentrations of a mixture of two insecticides and two fungicides (Indoxacarb, Tebuconazole, Thiacloprid and Trifloxystrobin) were reduced by more than 90% in 45 m experimental stream mesocosms. Plant density and solubility had the highest explanatory power for the response variable reduction of peak concentration (R² = 0.70, p < 0.001). Optimized vegetated streams can be highly effective in reduction of runoff related pesticide peak concentrations.

Pesticide Risk Mitigation by Vegetated Treatment Systems: A Meta-Analysis

Pesticides entering agricultural surface waters threaten water quality and aquatic communities. Recently, vegetated treatment systems (VTSs) (e.g., constructed wetlands and vegetated ditches) have been proposed as pesticide risk mitigation measures. However, little is known about the effectiveness of VTSs in controlling nonpoint source pesticide pollution and factors relevant for pesticide retention within these systems. Here, we conducted a meta-analysis on pesticide mitigation by VTSs using data from the scientific literature and the European LIFE ArtWET project. Overall, VTSs effectively reduced pesticide exposure levels (i.e., the majority of pesticide retention performances was >70%). A multiple linear regression analysis of 188 retention performance cases identified the two pesticide properties, organic carbon sorption coefficient value and water-phase 50% dissipation time, as well as the VTS characteristics overall plant coverage and hydraulic retention time for targeting high efficacy of pesticide retention. The application of a Tier I risk assessment (EU Uniform Principle) revealed a higher toxicity reduction for hydrophobic and nonpersistent insecticides compared with less sorptive and not readily degradable herbicides and fungicides. Overall, nearly half (48.5%) of all pesticide field concentrations ( = 130) failed Tier I standard risk assessment at the inlet of VTSs, and 29.2% of all outlet concentrations exceeded conservative acute threshold levels. We conclude that VTSs are a suitable and effective risk mitigation strategy for agricultural nonpoint source pesticide pollution of surface waters. Further research is needed to improve their overall efficacy in retaining pesticides.

Use of vegetated agricultural drainage ditches to decrease pesticide transport from tomato and alfalfa fields in California, USA

Irrigation and storm water runoff from agricultural fields has the potential to cause impairment to downstream aquatic receiving systems. Over the last several years, scientists have discovered the benefit of using edge-of-field practices, such as vegetated agricultural drainage ditches, in the mitigation of pesticides and sediment. After demonstrating this practice's feasibility in California, field trials were initiated to document irrigation runoff pesticide mitigation in California alfalfa and tomato fields. In the alfalfa field, chlorpyrifos concentration was decreased by 20% from the inflow to the ditch outflow. Thirty-two percent of the measured chlorpyrifos mass was associated with ditch plant material. In the tomato field, permethrin concentration was decreased by 67% and there was a 35% reduction in suspended sediment concentration from inflow to the ditch outflow. When surface water was not present in the ditch systems, the sediment was a significant repository for pesticides. Based on the field trials, vegetated agricultural drainage ditches can be successfully used as part of a suite of management practices to reduce pesticide and sediment runoff into aquatic receiving systems.

Ecological services of artificial wetland for pesticide mitigation Socio-technical adaptation for watershed management through TRUSTEA project feedback

Thanks to a R&D research program regarding artificial wetlands (TRUSTEA), we got the opportunity to improve the state of the art, assess the performance of artificial wetlands as ecological services and find economical, legal and social incentives for further nationwide extension. One artificial wetland was tested at pilot scales and an application on a real site is presented. Artificial wetland's test is based on tracer experiment in controlled conditions. Parameters of water and pesticide in and out flows have been measured and monitored. The application is based on the issue of groundwater preservation in a subsurface drained context. We also recorded the conditions of implementation since we were very close to real conditions. For this purpose, inquiries addressing the various actors were carried out by sociologists. The results of the performance regarding pesticide dissipation are shortly given. Sociologic approaches and amenities assessments have revealed unsuspected relations of the farmers with the society and the environment, and vice versa. The implementations have resulted of a co-construction where each actor had personal involvement. Even if co-construction should be a driving line, solutions for appropriate incentives and land reallocation tools should be fought with politics and authorities in order to facilitate further realizations.

Pesticide mitigation in museum collections : science in conservation : proceedings from the MCI workshop series

The Smithsonian Museum Conservation Institute Workshop on Pesticide Mitigation was one of the first professional meetings dedicated to current research on removing pesticide residues from museum objects. Seven papers were presented at the workshop, and two more were added to introduce topics not focused on during the meeting but of significant importance when considering actual application of any of these methods. The aim of the workshop was to bring together conservators, scientists, and even industry representatives to discuss the complex issues associated with pesticide removal from artifacts and to provide representative examples of the research and work being carried out at different institutions in the United States and abroad. Among the issues explored were possible methods and techniques that might become useful in the museum conservation field to reduce, mitigate, clean, or remediate undesirable pesticides on objects. The meeting also served to inform conservators and scientists in the Smithsonian Institution of the wide range of approaches that are currently being tested and that might prove useful in the future. Topics covered in the presented papers included removal of mercury and arsenic contamination with α-lipoic acid; the treatment of Haudenosaunee medicine masks with surface active displacement solutions; the possibility of using mercury-resistant bacterial communities to remediate contamination; solvent extraction through the use of special solvents such as hydrofluoroethers; carbon dioxide as a cleaning fluid either in liquid or in supercritical state; and novel cleaning techniques either through the use of additives to improve the efficiency of liquid or supercritical CO2 cleaning, other gases in a supercritical state, or other techniques such as fluidized beds. The introduction of novel techniques at the workshop was encouraged in order to broaden the range of promising methods that might improve the technology of pesticide mitigation or remediation. The two supplemental papers discuss pesticide analysis on objects and safety measures that should be implemented by institutions with contaminated collections

SWAT developments and recommendations for modelling agricultural pesticide mitigation measures in river basins

Pesticides are useful for agriculture because of their ability to protect crops against pests. At the same time, excessive loading of pesticides in water bodies can produce toxic conditions that harm sensitive aquatic species, and render the water unfit for human consumption. Therefore, measures need to be designed, evaluated and undertaken in order to reduce pesticide pollution. In this study we focus on the Nil catchment, a small basin situated in the centre of Belgium. The necessary database and a watershed model (Soil and Water Assessment Tool—SWAT) were available to simulate different agricultural management scenarios. In order to make the model accurately predict pesticide loading to the river and instream transport, it was necessary to make several modifications to the source code. Special attention was given to implement an estimator for point losses (e.g. cleaning of spray equipment) and droplet drift, and improve the representation of physical processes in filter strips. The closing of mass balances is also described. Once the model was modified and calibrated, it could be used to simulate the pesticide mitigation strategies and evaluate their effectiveness. The simulation results revealed that strip-cropping seems to be more efficient than the sowing of cover crops, contour farming, the construction of filter strips, a 40% reduction of point losses and finally conservation agriculture. Several recommendations are given for further improvement of SWAT for management use.

Use of toxicity identification evaluations to determine the pesticide mitigation effectiveness of on-farm vegetated treatment systems

Evidence of ecological impacts from pesticide runoff has prompted installation of vegetated treatment systems (VTS) along the central coast of California, USA. During five surveys of two on-farm VTS ponds, 88% of inlet and outlet water samples were toxic to Ceriodaphnia dubia. Toxicity identification evaluations (TIEs) indicated water toxicity was caused by diazinon at VTS-1, and chlorpyrifos at VTS-2. Diazinon levels in VTS-1 were variable, but high pulse inflow concentrations were reduced through dilution. At VTS-2, chlorpyrifos concentrations averaged 52% lower at the VTS outlet than at the inlet. Water concentrations of most other pesticides averaged 20-90% lower at VTS outlets. All VTS sediment samples were toxic to amphipods (Hyalella azteca). Sediment TIEs indicated toxicity was caused by cypermethrin and lambda-cyhalothrin at VTS-1, and chlorpyrifos and permethrin at VTS-2. As with water, sediment concentrations were lower at VTS outlets, indicating substantial reductions in farm runoff pesticide concentrations.

Methyl parathion toxicity in vegetated and nonvegetated wetland mesocosms

Methyl parathion (MeP) was introduced into constructed wetlands for the purpose of assessing the influence of emergent vegetation on transport and toxicity of the pesticide. Two vegetated (90% cover, mainly Juncus effusus) and two nonvegetated wetland cells (each with a water body of 50 x 5.5 x 0.2 m) were each dosed with 6.5 m3 of water containing active ingredient of MeP at 6.6 mg/L associated with suspended soil at 400 mg/L to simulate a storm runoff event. Acute toxicity was assessed by sampling benthic macroinvertebrates at 5, 10, 20, and 40 m from the inlet before and 96 h after contamination and by in situ exposure of Chironomus tentans (Diptera) up to 24 h after contamination. Methyl parathion was detected throughout the nonvegetated wetland cells (70 microg/L at 20 m, 8 microg/L at 40 m), whereas the pesticide was not transported through the vegetated wetland cells (20 microg/L at 20 m, < 0.1 microg/L at 40 m). A three-way analysis of variance using contamination (repeated measure variable), location, and vegetation indicated significant negative effects of contamination on various insect taxa, such as mayfly nymphs and caddisfly larvae. Seven out of the total of 15 species revealed a significant contamination x vegetation effect, with individuals in the vegetated wetlands being less affected. Four species showed a significant contamination x location effect, confirming a higher toxicity in the inlet area of the wetlands. A significant three-way interaction of contamination x vegetation x location was detected in Chironomus sp., which was most strongly affected at the inlet area of the nonvegetated wetland cells. The in situ bioassay employing C. tentans confirmed the positive effect of wetland vegetation on MeP toxicity. These results demonstrate the importance of vegetation for pesticide mitigation in constructed wetlands.

Mitigation of metolachlor-associated agricultural runoff using constructed wetlands in Mississippi, USA

A loss of marginal wetland acreage adjoining agricultural fields has created a potential problem with water quality enhancement of agricultural runoff via wetlands. Current research is investigating the utility of constructed wetlands for pesticide mitigation purposes, thereby restoring water quality enhancement capability to the area. Constructed wetland mesocosms (59–73 m×14 m), located at the University of Mississippi Field Station (Lafayette County, MS), were amended with metolachlor to simulate a cropland runoff event. Target concentrations for wetlands were 73 and 147 μg/l metolachlor in addition to an unamended control (0 μg/l). Water, sediment, and plant samples were collected weekly for 35 days following metolachlor amendment. Samples were collected from sites, longitudinally distributed within each wetland, and analyzed for metolachlor using gas chromatography. Between 7 and 25% of measured metolachlor mass was in the first 30–36 m (from inflow) of wetlands immediately following application and simulated rainfall. Approximately 10% of measured metolachlor mass was in plant samples. Suggested wetland travel distances for effective mitigation of metolachlor runoff ranged from 100 to 400 m. According to the results from this research, aquatic receiving system impacts due to metolachlor runoff could be mitigated by using constructed wetlands as buffers. Landowners and government agencies can integrate this information into a water management plan, allowing for better control of both quantity and quality of runoff water from individual agricultural fields.