Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands.
Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands; Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China.
Sci Total Environ. 2016 Dec 1;572:301-311. doi: 10.1016/j.scitotenv.2016.07.215. Epub 2016 Aug 6.
The dissipation kinetics of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) were studied in loess soil, under biotic and abiotic conditions, as affected by temperature, soil moisture (SM) and light/darkness. Nonsterile and sterile soil samples were spiked with 16mgkg of glyphosate, subjected to three SM contents (20% WHC, 60% WHC, saturation), and incubated for 30days at 5°C and 30°C, under dark and light regimes. Glyphosate and AMPA dissipation kinetics were fit to single-first-order (SFO) or first-order-multicompartment (FOMC) models, per treatment combination. AMPA kinetic model included both the formation and decline phases. Glyphosate dissipation kinetics followed SFO at 5°C, but FOMC at 30°C. AMPA followed SFO dissipation kinetics for all treatments. Glyphosate and AMPA dissipation occurred mostly by microbial activity. Abiotic processes played a negligible role for both compounds. Under biotic conditions, glyphosate dissipation and AMPA formation/dissipation were primarily affected by temperature, but also by SM. Light regimes didn't play a significant role. Glyphosate DT50 varied between 1.5 and 53.5days, while its DT90 varied between 8.0 and 280days, depending on the treatment. AMPA persisted longer in soil than glyphosate, with its DT50 at 30°C ranging between 26.4 and 44.5days, and its DT90 between 87.8 and 148days. The shortest DT50/DT90 values for both compounds occurred at 30°C and under optimal/saturated moisture conditions, while the largest occurred at 5°C and reaching drought stress conditions. Based on these results, we conclude that glyphosate and AMPA dissipate rapidly under warm and rainy climate conditions. However, repeated glyphosate applications in fallows or winter crops in countries where cold and dry winters normally occur could lead to on-site soil pollution, with consequent potential risks to the environment and human health. To our knowledge, this study is the first evaluating the combined effect of temperature, soil moisture and light/dark conditions on AMPA formation/dissipation kinetics and behaviour.
在生物和非生物条件下，研究了草甘膦及其代谢物氨甲基膦酸（AMPA）在黄土中的消解动力学，受温度、土壤水分（SM）和光照/黑暗的影响。非无菌和无菌土壤样品中加入 16mgkg 的草甘膦，分别置于 20%WHC、60%WHC 和饱和 3 种土壤水分含量下，在 5°C 和 30°C、黑暗和光照条件下培养 30 天。根据处理组合，草甘膦和 AMPA 消解动力学均拟合为单一级（SFO）或一级多区（FOMC）模型。AMPA 动力学模型包括形成和衰减阶段。在 5°C 时，草甘膦消解动力学遵循 SFO，但在 30°C 时遵循 FOMC。所有处理的 AMPA 均遵循 SFO 消解动力学。草甘膦和 AMPA 的消解主要由微生物活性引起。非生物过程对这两种化合物的影响可以忽略不计。在生物条件下，草甘膦的消解和 AMPA 的形成/消解主要受温度影响，但也受 SM 影响。光照条件没有起到显著作用。草甘膦 DT50 在 1.5 到 53.5 天之间变化，而 DT90 在 8.0 到 280 天之间变化，这取决于处理方式。AMPA 在土壤中比草甘膦更持久，其在 30°C 时的 DT50 在 26.4 到 44.5 天之间变化，DT90 在 87.8 到 148 天之间变化。这两种化合物在 30°C 和最佳/饱和水分条件下的 DT50/DT90 值最短，而在 5°C 和达到干旱胁迫条件下的 DT50/DT90 值最大。根据这些结果，我们得出结论，草甘膦和 AMPA 在温暖多雨的气候条件下迅速消解。然而，在寒冷和干燥的冬季通常发生的国家，在休耕期或冬季作物中重复使用草甘膦可能会导致现场土壤污染，从而对环境和人类健康造成潜在风险。据我们所知，这项研究是首次评估温度、土壤水分和光照/黑暗条件对 AMPA 形成/消解动力学和行为的综合影响。
