Winchell Michael F, Pai Naresh, Brayden Benjamin H, Stone Chris, Whatling Paul, Hanzas John P, Stryker Jody J
J Environ Qual. 2018 Jan;47(1):79-87. doi: 10.2134/jeq2017.06.0238.
The estimation of pesticide concentrations in surface water bodies is a critical component of the environmental risk assessment process required by regulatory agencies in North America, the European Union, and elsewhere. Pesticide transport to surface waters via deposition from off-field spray drift can be an important route of potential contamination. The spatial orientation of treated fields relative to receiving water bodies make prediction of off-target pesticide spray drift deposition and resulting aquatic estimated environmental concentrations (EECs) challenging at the watershed scale. The variability in wind conditions further complicates the simulation of the environmental processes leading to pesticide spray drift contributions to surface water. This study investigates the use of the Soil Water Assessment Tool (SWAT) for predicting concentrations of malathion (O,O-deimethyl thiophosphate of diethyl mercaptosuccinate) in a flowing water body when exposure is a result of off-target spray drift, and assesses the model's performance using a parameterization typical of a screening-level regulatory assessment. Six SWAT parameterizations, each including incrementally more site-specific data, are then evaluated to quantify changes in model performance. Results indicate that the SWAT model is an appropriate tool for simulating watershed scale concentrations of pesticides resulting from off-target spray drift deposition. The model predictions are significantly more accurate when the inputs and assumptions accurately reflect application practices and environmental conditions. Inclusion of detailed wind data had the most significant impact on improving model-predicted EECs in comparison to observed concentrations.
估算地表水体中的农药浓度是北美、欧盟及其他地区监管机构所要求的环境风险评估过程的关键组成部分。农药通过场外喷雾飘移沉降进入地表水是潜在污染的一条重要途径。施药农田相对于受纳水体的空间方位使得在流域尺度上预测非靶标农药喷雾飘移沉降及由此产生的水生生物估计环境浓度（EECs）具有挑战性。风况的变化进一步使导致农药喷雾飘移对地表水产生影响的环境过程模拟变得复杂。本研究探讨了利用土壤水评估工具（SWAT）预测当暴露源为非靶标喷雾飘移时流动水体中马拉硫磷（二乙基巯基琥珀酸酯的O,O -二甲基硫代磷酸酯）的浓度，并使用筛选级监管评估的典型参数设置来评估该模型的性能。随后对六种SWAT参数设置进行评估，每种参数设置包含的特定场地数据逐渐增多，以量化模型性能的变化。结果表明，SWAT模型是模拟非靶标喷雾飘移沉降导致的流域尺度农药浓度的合适工具。当输入数据和假设准确反映施药实践和环境条件时，模型预测的准确性显著提高。与观测浓度相比，纳入详细的风数据对改善模型预测的EECs影响最为显著。
