红壤性水稻田土壤-水-植物系统中毒死蜱的迁移转化和分布特征

为了探究毒死蜱在红壤性水稻田土壤、水、植物系统中的迁移转化和分布特征，通过室内批量平衡吸附实验、野外喷施试验与动态观测，研究了持续淹水和间歇淹水条件下红壤性水稻土-水-水稻系统中毒死蜱的迁移转化和分布特征。结果表明：毒死蜱在呈酸性的红壤性水稻土中易于淋失迁移至深层土壤（可达50 cm）；白昼的高温导致表层土壤孔隙水中毒死蜱及其主要降解产物3，5，6-三氯-2-吡啶醇（TCP）的浓度显著上升，而降雨事件促进两者向深层土壤迁移；水稻收获时土壤中毒死蜱残留量较高，且其剖面分布较为均匀；间歇淹水处理可使收获时水稻籽粒和茎秆中的毒死蜱残留量降低为持续淹水处理水稻相应部位的0.69倍和0.84倍。研究显示，红壤性水稻土壤中毒死蜱的淋溶作用较强，不同的灌溉方式对收获期水稻中毒死蜱的含量有显著影响。

Transport and distribution of chlorpyrifos in soil-water-plant system of paddy field developed from red soil

The transport and distribution of pesticides in paddy field soil-water system constitute a serious danger to human and ecosystem health. This study investigated the transport and distribution of chlorpyrifos as a commonly used pesticide in paddy field of red soil through laboratory batch equilibrium adsorption experiments and field study. The study was conducted under continuous and intermittent flooding conditions through field pesticide application and subsequent continuous monitoring. The results showed that chlorpyrifos leached strongly to a depth of 50 cm in the paddy soil and the high daytime temperature caused increases in concentrations of chlorpyrifos and its main degradation product, 3,5,6-trichloro-2-pyridinol(TCP), in the pore water of the surface soil layer. Rain events promoted the transport of chlorpyrifos and TCP toward the deep soil layer. Chlorpyrifos residue in the soil at the time of rice harvesting was high and it was uniformly distributed in the soil profile. Intermittent irrigation reduced the chlorpyrifos contents in rice grains and stems. Chlorpyrifos contents in rice grains and stems under intermittent irrigation were 0.69 and 0.84 times those in rice grains and stems under continuous irrigation, respectively. This study suggests that chlorpyrifos could leach in paddy field developed from red soil, and different irrigation methods have a significant effect on the content of chlorpyrifos in harvested rice.