Sources and fate of glyphosate and aminomethylphosphonic acid in field crops soils

在过去的二十年里，草甘膦除草剂（GBH）与草甘膦耐受性作物的联合使用在世界各地的大田作物农业中呈指数增长。因此，草甘膦及其主要降解产物氨甲基膦酸（AMPA）在环境中普遍存在。该DG研究计划的长期愿景侧重于了解草甘膦和AMPA在各种农业实践中的动态，并确定土壤生物和非生物成分在降解，再活化或积累这些化学品中所起的作用。最终，它的目的是强调保护性农业的最佳做法，限制GBH的使用，同时提高GBH的降解。 目前的发现研究计划是基于我的环境地球化学实验室开发的两个分析突破，即使用GC-ECD常规分析土壤和植物中草甘膦和AMPA的痕迹，并使用新获得的LC-IRMS测量草甘膦和AMPA的化合物特异性d13 C。在整个项目中，将追求三个互补的短期研究目标，并与农民进行长期合作：1）估计草甘膦和AMPA在土壤中的降解和持久性。为此，将进行实验室和野外实验，以沿着农业作业，了解草甘膦和AMPA含量的变化以及土壤中d13 C的特征。 2)通过GBH和生物固体评估草甘膦和AMPA各自的土壤输入。废水生物固体改良剂可能是土壤中草甘膦和AMPA的来源。使用GBH批次的草甘膦d13 C签名与生物固体中的草甘膦和AMPA不同的实验设置应允许区分由生物固体或GBH带到农业土壤的两种化合物的相对动态。3)确定有机农业系统中草甘膦和AMPA的来源。在长期建立的有机农田作物系统的土壤中检测到草甘膦和AMPA。测量各种农业投入物（如粪肥）中的草甘膦和AMPA d13 C特征将有助于确定有机农业土壤中这些化合物的来源和持久性。使用GBH来控制杂草与免耕的做法，和/或回收城市生物固体肥料残留作为管理实践保持或恢复土壤功能，保持生物多样性和应对气候变化。只有在草甘膦和AMPA在土壤中的持久性很短的情况下，这种关于大田作物系统可持续性的论点才有效。因此，了解这些化学品在土壤中消散的机制至关重要。该计划将为HQP提供一个刺激的环境，将复杂的分析技术培训与对复杂和战略性农业环境问题的广泛理解相结合。

The usage of glyphosate-based herbicides (GBH) in association with glyphosate tolerant crops increased exponentially in field crop agriculture throughout the world for the past two decades. Consequently, glyphosate and its main degradation product, aminomethylphosphonic acid (AMPA), are ubiquitously detected in the environment. The long-term vision of this DG research program focuses on understanding the dynamics of glyphosate and AMPA with respect to various agricultural practices, and on identifying the role played by the soil biotic and abiotic constituents in degrading, remobilizing or accumulating, those chemicals. Ultimately, it is intended to highlight best practices in conservation agriculture limiting GBH usage while enhancing GBH degradation. The present Discovery research program is based on two analytical breakthroughs developed in my Environmental Geochemistry Laboratory, i.e. routinely analyzing traces of glyphosate and AMPA in soils and plants using a GC-ECD, and measuring compound-specific d13C of glyphosate and AMPA with a newly acquired LC-IRMS. Three complementary short-term research objectives will be pursued throughout the program with the benefit of long-term collaboration with farmers: 1) Estimate the degradation and persistence of glyphosate and AMPA in soils. To do so, laboratory and open field experiments will be conducted to follow along with agricultural operations the evolution of glyphosate and AMPA contents and d13C signatures in soils. 2) Evaluate the respective soil inputs of glyphosate and AMPA by GBH and biosolids. Wastewater biosolid amendments could represent a source of glyphosate and AMPA to soils. An experimental setting using GBH lots with a glyphosate d13C signature distinct from that of glyphosate and AMPA in biosolids should allow distinguishing the relative dynamics of both compounds brought to agricultural soils either by biosolids or by GBH. 3) Identify the source of glyphosate and AMPA in organic farming systems. Glyphosate and AMPA are detected in soils of long-established organic field crop systems. Measurements of glyphosate and AMPA d13C signatures in various farm inputs such as manure will allow identifying the sources and persistence of these compounds in organic farming soils. Using GBH to control weeds with no-till practices, and / or recycling municipal biosolids as fertilizer residual are presented as management practices keeping or restoring soil functions, maintaining biodiversity and fighting climate change. This argument towards sustainability of field crops systems is only valid if glyphosate and AMPA's persistence in soil is short. Understanding the mechanisms responsible for the dissipation of these chemicals in soils is thus of utmost importance. The program will offer a stimulating environment for HQP, combining training on sophisticated analytical techniques with the broad understanding of complex and strategic agri-environmental issues.