CAS: Understanding Glyphosate's Reactions at Mineral and Organic-Coated Mineral Surfaces: Sorption-Desorption Dynamics

美国国家科学基金会化学部的环境化学科学计划资助康奈尔大学的Carmen Enid Martínez教授研究草甘膦与土壤中存在的矿物和有机涂层矿物表面的反应动力学。草甘膦是世界上应用最广泛的除草剂，用于杀死阔叶植物和牧草。因此，草甘膦对环境的污染在美国的土壤、沉积物、地表水和地下水中频繁而广泛地发生。草甘膦与土壤的相互作用极大地影响了草甘膦的环境行为，包括毒性、移动性和生物利用度。该项目的目标是了解草甘膦在与土壤成分相互作用时如何以及以多快的速度保持和释放。鉴于草甘膦的广泛使用，了解其积累的条件是至关重要的。令人感兴趣的还有它与土壤成分的反应是否创造了一个具有缓释能力的水库，这是造成地表水和地下水污染的一条途径。该项目为研究生提供研究机会和培训。该项目结合了科学中心(纽约州伊萨卡)的外展部分，以及与NYS 4-H和康奈尔合作扩展项目的外展活动。研究生参加所有支持他们发展和专业培训的外展活动。该项目提供关于草甘膦在矿物和有机包覆矿物表面的分子尺度过程的全面信息。最主要的问题是：草甘膦在土壤中积累吗？它的积累是一个可逆的过程吗？研究活动旨在检验这样一种假设，即矿物和有机涂层矿物表面保留(吸附)和释放(解吸)草甘膦的能力不同，矿物表面对草甘膦的吸附胜过对溶解有机物的吸附。研究了草甘膦吸附-解吸的相互作用机理和动力学，使用了代表各种表面结构的矿物，以及有机涂层在结构特征、官能度和芳香性方面不同的有机涂层矿物。这些过程的分子尺度吸附-解吸行为和动力学是利用表面敏感方法结合从这些实验中流出的溶液的同时分析来探索的。获得了有助于解释草甘膦吸附-解吸行为(结合常数、最大吸附)及其速率常数的基于过程的参数。同时监测表面反应和溶液化学有助于更全面地了解分子尺度的过程。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Environmental Chemical Sciences Program of the NSF Division of Chemistry funds Professor Carmen Enid Martínez at Cornell University to study the dynamics of glyphosate reaction with mineral and organic-coated mineral surfaces present in soils. Glyphosate is the world’s most heavily applied herbicide used to kill broadleaf plants and grasses. As a result, environmental contamination with glyphosate occurs frequently and widely in U.S. soils, sediments, surface and groundwater. Glyphosate’s interaction with soil greatly influences glyphosate’s environmental behavior including toxicity, mobility, and bioavailability. The goal of this project is to learn how and how fast glyphosate is retained and released upon interaction with soil components. Given the widespread use of glyphosate, it is essential to understand the conditions for its accumulation. Of interest is also whether its reactions with soil components create a reservoir with slow-release capability, which is a route to surface and groundwater contamination. This project provides research opportunities and training for graduate students. The project integrates an outreach component with the Sciencenter (Ithaca, NY), and outreach activities with NYS 4-H and Cornell Cooperative Extension. Graduate students participate in all outreach activities which supports their development and professional training.This project provides comprehensive information on molecular-scale processes of glyphosate at mineral and organic-coated mineral surfaces. The overarching question is: Does glyphosate accumulate in soils, and is its accumulation a reversible process? Research activities are designed to test the hypothesis that mineral and organic-coated mineral surfaces differ in their ability to retain (sorb) and release (desorb) glyphosate, and that glyphosate sorption at mineral surfaces outcompetes sorption of dissolved organic matter. Mechanisms of interaction and kinetics of glyphosate sorption-desorption are investigated using minerals that represent a variety of surface structures, and organic-coated minerals where the organic-coating differ in structural characteristics, functionality and aromaticity. Molecular-scale sorption-desorption behavior and kinetics of these processes are probed utilizing surface sensitive approaches coupled to simultaneous analyses of outflow solutions from these experiments. Process-based parameters are obtained that help explain glyphosate sorption-desorption behavior (binding constants, sorption maximum) and their rate constants. The simultaneous monitoring of surface reactions and solution chemistry facilitates a more comprehensive understanding of molecular-scale processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.