Wang Meichen, Orr Asuka A, He Shujun, Dalaijamts Chimeddulam, Chiu Weihsueh A, Tamamis Phanourios, Phillips Timothy D
Veterinary Integrative Biosciences Department, College of Veterinary Medicine and Biomedical Sciences and Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
ACS Omega. 2019 Oct 17;4(18):17702-17713. doi: 10.1021/acsomega.9b02051. eCollection 2019 Oct 29.
Among the numerous contaminants of soil, glyphosate and paraquat are two of the most widely used herbicides that are commonly detected in the environment. Soil and sediment contaminated with glyphosate, paraquat, and other environmental toxins can be mobilized and redistributed to lawns, vegetable gardens, parks, and water supplies in vulnerable communities at the site of disasters such as hurricanes and flooding. Glyphosate and paraquat bind strongly to soils containing clays, making their bioavailability (bioaccessibility) from these types of soil very low. Because of their affinity for clay-based soils, it is possible that montmorillonite clays could be administered as a therapeutic agent in the diet of animals and humans to decrease short-term exposure and toxicity. In this study, we investigated the sorption mechanisms of glyphosate and paraquat onto active surfaces of calcium montmorillonite (CM) and sodium montmorillonite (SM) clays and derived binding parameters, including capacity, affinity, and enthalpy. Additionally, we used these parameters to predict the reduction in bioavailability under different pH and temperature conditions and to estimate the theoretical dose of clay that could protect against severe paraquat toxicity and lethality. Computational modeling and simulation studies depicted toxin sorption mechanisms at different pH values. Additionally, a toxin-sensitive living organism () was used to confirm the safety of the clay and its ability to protect against toxicity from glyphosate and paraquat. The high efficacy of CM and SM shown in this study supports the natural binding activity of glyphosate and paraquat to clay-based soils. Following disasters and medical emergencies, montmorillonite clays could be administered by capsules and tablets, or added to food and flavored water, to reduce toxin bioavailability and human and animal exposures.
在土壤的众多污染物中，草甘膦和百草枯是两种使用最为广泛的除草剂，在环境中普遍可检测到。受到草甘膦、百草枯及其他环境毒素污染的土壤和沉积物，在飓风和洪水等灾害发生地，可能会被转移并重新分布到脆弱社区的草坪、菜园、公园及供水系统中。草甘膦和百草枯与含黏土的土壤紧密结合，使得它们从这类土壤中的生物有效性（生物可及性）非常低。由于它们对黏土类土壤具有亲和力，蒙脱石黏土有可能作为治疗剂添加到动物和人类的饮食中，以减少短期接触及毒性。在本研究中，我们调查了草甘膦和百草枯在钙蒙脱石（CM）和钠蒙脱石（SM）黏土活性表面上的吸附机制，并得出了结合参数，包括容量、亲和力和焓。此外，我们利用这些参数预测了不同pH值和温度条件下生物有效性的降低情况，并估算了可预防严重百草枯毒性和致死性的黏土理论剂量。计算建模和模拟研究描绘了不同pH值下的毒素吸附机制。此外，还使用了一种对毒素敏感的活生物体来确认黏土的安全性及其预防草甘膦和百草枯毒性的能力。本研究中CM和SM所显示的高效性支持了草甘膦和百草枯与黏土类土壤的天然结合活性。在灾害和医疗紧急情况发生后，蒙脱石黏土可制成胶囊和片剂服用，或添加到食物和调味水中，以降低毒素的生物有效性，减少人和动物的接触。
