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Fate and transport of agricultural chemicals in the Yazoo River Basin.

机译：亚佐河流域的农药命运与运输。

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The objectives of this research were to examine some representative surface waters in the Yazoo River Basin (YRB) during the growing season for a few selected herbicides; to compare the type and abundance of pesticides in the atmosphere at a agricultural and an urban site; to determine the load of nitrogen and phosphorus being discharged from the YRB to the Mississippi River and ultimately the Gulf of Mexico; to determine how the adsorptive properties of a common Delta soil differ under no-tillage (NT) versus conventional tillage (CT) for two commonly used herbicides; and to validate the Soil and Water Assessment Tool (SWAT) model for herbicide runoff in the YRB.; Herbicides, in low concentrations (generally less than 10 parts per billion) were frequently detected in 3 streams in the YRB throughout the growing season. Pesticides were detected in air and rain samples from both urban and agricultural areas. The concentrations in the agricultural area generally were an order of magnitude higher and types of pesticides detected were different: more insecticides in the urban area and more herbicides in the agricultural area. The annual load of nitrogen being contributed to the Mississippi River from the YRB was less than what might be expected based on discharge, and the load of phosphorus was slightly higher than what might be expected. The amount of atrazine and fluometuron adsorbed was similar for a soil under CT and NT, but much more herbicide was adsorbed by the NT soil. At the scale of the Bogue Phalia Basin (too large for specific information to be available and too small for averaging to eliminate the need for site specific data) there are considerable uncertainties associated with input data and these, together with the simplifying assumptions within the model, mean that SWAT should not be used to predict the exact date, time, and concentration of a pesticide in a stream. However, the model does offer the potential to assess the likelihood of contamination of surface waters by a given compound in a given situation and as such could provide a useful tool for planning, management and regulatory purposes.
机译：这项研究的目的是在生长期中，对Yazoo河流域（YRB）的一些代表性地表水进行研究，以选择几种除草剂。比较农业和城市地区大气中农药的种类和含量；确定从YRB排放到密西西比河并最终排放到墨西哥湾的氮和磷的负荷；确定在两种耕作除草剂的免耕（NT）与常规耕作（CT）下普通三角洲土壤的吸附特性如何不同；并验证黄河三角洲除草剂径流的土壤和水评估工具（SWAT）模型；在整个生长季节，黄河三角洲的3条溪流中经常检测到低浓度的除草剂（通常少于十亿分之十）。在城市和农业地区的空气和雨水样品中都检出了农药。农业地区的浓度通常要高一个数量级，而检测到的农药类型却有所不同：城市地区的杀虫剂更多，农业地区的除草剂更多。从黄河三角洲流向密西西比河的氮的年负荷低于基于排放的预期，磷的负荷略高于预期。对于CT和NT下的土壤，阿特拉津和氟美隆的吸附量相似，但是NT上吸附的除草剂更多。在博格帕利亚盆地的规模上（太大而无法获得特定信息，而太小而无法进行平均以消除对特定地点数据的需求），输入数据存在很大的不确定性，这些不确定性以及模型中的简化假设，表示不应使用SWAT预测河流中农药的确切日期，时间和浓度。然而，该模型确实提供了评估给定情况下给定化合物污染地表水的可能性的潜力，因此可以为规划，管理和监管目的提供有用的工具。

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