Coupling diazinon volatilization and water evaporation in unsaturated soils: II. Diazinon transport.
Coupling diazinon volatilization and water evaporation in unsaturated soils: II. Diazinon transport.
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DOI：
10.1097/00010694-200009000-00001
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发表时间：
2000-09
期刊：
影响因子：
--
通讯作者：
Dong Chen;D. Rolston
中科院分区：
文献类型：
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作者：
Dong Chen;D. Rolston
土壤中农药的挥发是导致化学品向非目标区域迁移的关键过程之一。本研究主要探讨土壤水分迁移对农药挥发的影响。研究了土壤中二嗪磷[O，O二乙基O-（2-异丙基-4-甲基-6-嘧啶基）硫代磷酸酯]在不同土壤初始含水量和土壤水分蒸发条件下的挥发行为。这些条件是不同的，通过湿空气和干N2交替通过土壤表面。当在高初始水含量塔中使用干燥吹扫气（N2）时，由于明显的向上水流，二嗪农挥发加速。当向上的水流不足以满足蒸发需求时，土壤表面的土壤水分含量迅速降低到阈值以下，并且由于二嗪农吸附在干燥的土壤表面上，二嗪农挥发开始呈指数下降。当吹扫气切换为增湿空气时，土壤表面吸附水和二嗪磷挥发量急剧增加。建立了等温条件下农药在土壤中运移的数学模型。计算和测量的二嗪农挥发通量一致，但该模型高估了二嗪农浓度在较深的土壤深度显着。
Volatilization of pesticides from soil is one of the key processes causing transport of chemicals to non-target areas. This study focuses on how water transport in the surface soil affects volatilization of pesticides. Volatilization of soil-incorporated diazinon [O, O diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate] was measured under different initial soil-water contents and soil-water evaporation conditions. These conditions were varied by passing wet air and dry N2 alternately across the soil surface. When dry sweep gas (N2) was used in high initial water content columns, diazinon volatilization was accelerated as a result of appreciable upward water flow. When upward water flow was insufficient to meet evaporative demand, soil-water content at the soil surface was quickly reduced below a threshold, and diazinon volatilization started to decrease exponentially because of diazinon adsorption on the dry soil surfaces. When the sweep gas was switched to humidified air, the soil surface adsorbed water and diazinon volatilization increased dramatically. A numerical model was developed to simulate pesticide transport in soil for isothermal conditions. The calculated and measured diazinon volatilization fluxes agreed well, but the model overestimated diazinon concentrations in the deeper depths of the soil significantly.