ABSTRACT

Chlorpyrifos is an extensively used insecticide in the agriculture worldwide and was often detected in both surface waters and groundwater, posing threats to local residents’ health. Temporal changes and environmental fate of chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP; the main degradation product of chlorpyrifos) were studied in field paddy lysimeters. On the other hand, batch sorption tests of both chlorpyrifos and TCP and dissipation test of chlorpyrifos under submerged condition were conducted for the paddy soil in the laboratory. Following field application, concentration of chlorpyrifos in the floodwater decreased rapidly by >90% of the initial concentration in the first two days. Higher temperature during the daytime, as compared to the nighttime, could not only lead to larger dissipation rates of chlorpyrifos and TCP in the floodwater in the first two days, but also cause greater release of TCP into the soil pore water for more days. A rain event at an early time (i.e., day 2) caused a transient peak release of chlorpyrifos and TCP into the soil pore water; however, no such changes occurred upon later rain or irrigation event(s). In future studies, due attention should be paid to the risk of the runoff and leaching of the weakly sorbing TCP.

摘要

毒死蜱是全球农业中广泛使用的杀虫剂，经常在地表水和地下水中检测到，对当地居民的健康构成威胁。在稻田蒸渗仪中研究了毒死蜱和 3,5,6-trichloro-2-pyridinol（TCP；毒死蜱的主要降解产物）的时间变化和环境归宿。另一方面，在实验室对水稻土进行了毒死蜱和TCP的批量吸附试验和浸没条件下毒死蜱的消散试验。现场施用后，洪水中毒死蜱的浓度在前两天迅速下降 > 90% 的初始浓度。与夜间相比，白天温度较高，不仅会导致前两天洪水中毒死蜱和 TCP 的消散率增加，而且会导致 TCP 在更多天数内更多地释放到土壤孔隙水中。早期（即第 2 天）的降雨事件导致毒死蜱和 TCP 释放到土壤孔隙水中的瞬时峰值；然而，在后来的降雨或灌溉事件中没有发生这种变化。在未来的研究中，应充分注意弱吸附 TCP 的径流和淋溶风险。