汾河流域农田土壤草甘膦的分布、降解及迁移特征

Distribution, degradation and migration characteristics of Glyphosate in agricultural soil from Fenhe River basin

[目的]汾河流域是山西省重要粮食产地,长期大量施用草甘膦导致其在土壤中聚集,严重威胁着汾河流域的土壤质量以及周边环境的安全。本文旨在研究草甘膦在汾河流域的分布、降解及迁移特征。[方法]测定汾河流域农田土壤中草甘膦的含量,掌握草甘膦在汾河流域农田土壤中的分布特征,通过室内培养、土柱淋溶试验,研究草甘膦在施用后的降解、迁移规律。[结果]草甘膦及其降解产物氨甲基磷酸(AMPA)主要集中在0~20 cm土层,4月、7月和10月草甘膦的含量为分别为2.20~45.4、11.9~153和6.60~143μg·kg-1,AMPA的含量为11.1~165、71.8~362和20.3~343μg·kg-1。草甘膦在汾河流域农田土壤中的半衰期为3~5 d,施入草甘膦30 d后,土壤中草甘膦残留量基本稳定。淋溶作用使草甘膦及AMPA沿土壤剖面迁移至35~50 cm土层,50 cm以下土层草甘膦及AMPA含量接近自然土壤。[结论]本研究通过室内培养、土柱淋溶试验初步探索了草甘膦施入土壤后的降解及迁移规律,结果可为汾河流域农田土壤草甘膦污染治理提供理论依据与数据支撑。

[Objective]0Fenhe River Basin is an important grain producing area in Shanxi Province. Long-term and heavy use of glyphosate causes pollutant accumulation in soil, which threatens soil quality of Fenhe River basin and safety of surrounding environment.[Methods]In this study, the concentration of glyphosate in agricultural soil of Fenhe River Basin was determined, and the degradation and migration characteristics of glyphosate after application were studied by culture and soil column leaching experiments.[Results]Glyphosate and its degradation product ammethylphosphoric acid(AMPA) were mainly concentrated in 0~20 cm soil layer. The contents of glyphosate in April, July and October were 2. 2~45. 4,11. 9~153. 3 and 6. 6~143. 2 μg·kg-1, respectively. The contents of AMPA in April, July and October were 11. 1~165. 4、71. 8~361. 6 and 20. 3~342. 6 μg·kg-1. The half-life of glyphosate in soil of Fenhe River Basin was 3 to 5 days, and the glyphosate residue in soil was basically stable after 30 days of application. Leaching made glyphosate and AMPA migrate along the soil profile to the soil layer of 35~50 cm. The content of glyphosate and AMPA in soil layer below 50 cm is close to natural soil.[Conclusion]In this study, the degradation and migration of glyphosate in soil were investigated by culture and soil column leaching experiments. The results can provide theoretical basis and data support for glyphosate pollution control in farmland soil of Fenhe River Basin.