Mamy Laure, Barriuso Enrique, Gabrielle Benoît
Unit of Environment and Arable Crops, National Institute for Agronomic Research, 78850 Thiverval-Grignon, France.
Pest Manag Sci. 2005 Sep;61(9):905-16. doi: 10.1002/ps.1108.
The introduction of crops resistant to the broad spectrum herbicide glyphosate, N-(phosphonomethyl)glycine, may constitute an answer to increased contamination of the environment by herbicides, since it should reduce the total amount of herbicide needed and the number of active ingredients. However, there are few published data comparing the fate of glyphosate in the environment, particularly in soil, with that of substitute herbicides. The objective of this study is to compare the fate of glyphosate in three soils with that of four herbicides frequently used on crops that might be glyphosate resistant: trifluralin, alpha,alpha,alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine, and metazachlor, 2-chloro-N-(pyrazol-1-ylmethyl)acet-2',6'-xylidide for oilseed rape, metamitron, 4-amino-4,5-dihydro-3-methyl-6-phenyl-1,2,4-triazin-5-one for sugarbeet and sulcotrione, 2-(2-chloro-4-mesylbenzoyl)cyclohexane-1,3-dione for maize. The distribution of herbicides between the volatilized, mineralized, extractable and non-extractable fractions was studied, along with the formation of their metabolites in laboratory experiments using 14C-labelled herbicides, over a period of 140 days. The main dissipation pathways were mineralization for glyphosate and sulcotrione, volatilization for trifluralin and non-extractable residues formation for metazachlor and metamitron. The five herbicides had low persistence. Glyphosate had the shortest half-life, which varied with soil type, whereas trifluralin had the longest. The half-lives of metazachlor and sulcotrione were comparable, whereas that of metamitron was highly variable. Glyphosate, metazachlor and sulcotrione were degraded into persistent metabolites. Low amounts of trifluralin and metamitron metabolites were observed. At 140 days after herbicide applications, the amounts of glyphosate and its metabolite residues in soils were the lowest in two soils, but not in the third soil, a loamy sand with low pH. The environmental advantage in using glyphosate due to its rapid degradation is counterbalanced by accumulation of aminomethylphosphonic acid specifically in the context of extensive use of glyphosate.
引入对广谱除草剂草甘膦（N-（膦酰基甲基）甘氨酸）具有抗性的作物，可能是应对除草剂对环境造成污染加剧问题的一个办法，因为这应该会减少所需除草剂的总量以及活性成分的数量。然而，关于草甘膦与替代除草剂在环境中，尤其是在土壤中的归宿对比的已发表数据很少。本研究的目的是比较草甘膦在三种土壤中的归宿与四种常用于可能抗草甘膦作物上的除草剂的归宿：氟乐灵（α,α,α-三氟-2,6-二硝基-N,N-二丙基对甲苯胺）、甲草嗪（2-氯-N-（吡唑-1-基甲基）乙酰-2',6'-二甲基苯胺，用于油菜）、嗪草酮（4-氨基-4,5-二氢-3-甲基-6-苯基-1,2,4-三嗪-5-酮，用于甜菜）和磺草酮（2-（2-氯-4-甲磺酰基苯甲酰基）环己烷-1,3-二酮，用于玉米）。在实验室实验中，使用14C标记的除草剂，研究了140天内除草剂在挥发、矿化、可提取和不可提取部分之间的分布情况，以及它们代谢物的形成。主要的消散途径是草甘膦和磺草酮的矿化、氟乐灵的挥发以及甲草嗪和嗪草酮形成不可提取的残留物。这五种除草剂的持久性较低。草甘膦的半衰期最短，且随土壤类型而变化，而氟乐灵的半衰期最长。甲草嗪和磺草酮的半衰期相当，而嗪草酮的半衰期变化很大。草甘膦、甲草嗪和磺草酮会降解为持久性代谢物。观察到氟乐灵和嗪草酮的代谢物含量较低。在施用除草剂140天后，草甘膦及其代谢物残留物在两种土壤中的含量最低，但在第三种土壤（低pH值的砂壤土）中并非如此。由于草甘膦降解迅速而在使用上具有的环境优势，在草甘膦大量使用的情况下，会因氨甲基膦酸的积累而被抵消。
