Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Av. Reina Mercedes, 10. Seville, E-41012, Spain.
Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Av. Reina Mercedes, 10. Seville, E-41012, Spain.
Sci Total Environ. 2017 Sep 1;593-594:787-795. doi: 10.1016/j.scitotenv.2017.03.202. Epub 2017 Mar 30.
Glyphosate (GPS) is an herbicide currently used on olive crops in Spain, and can be transported to the nearby reservoirs currently used for human consumption. The purpose of this work was to study the behaviour and environmental fate of GPS in water and sediments of the Vibora Reservoir, its tributary river, and the surrounding agricultural soils to assess the risk of water pollution of this reservoir. The adsorption of GPS by different matrices was as follows: heading of the reservoir sediment (Cabecera)>tail sediment (Cola)>soils>Vibora sediment. The highest amount of oxides (especially Fe oxides) was observed in sediments from Cabecera and Cola whereas the lowest values were recorded on Vibora sediment. Results indicate that the highest GPS adsorption is due to the amorphous oxides and the edge sites of the clay minerals. Glyphosate adsorption increased with decreasing pH from 8 to 7. The desorption percentage of GPS from the four soils studied ranged only from 0.40 to 1.22%. Desorption was almost irreversible for Cabecera and Cola sediments, with values between 0 and 1.1%. Conversely, Vibora sediment presented about 20% desorption, probably due to its coarse texture and lower levels of amorphous oxides. Hockey-stick first-order kinetics was the best descriptor for water glyphosate dissipation at the Cabecera and Cola locations, and simple first-order kinetic for the water from the tributary Vibora River. The half-lives (DT50) were between 6.3 and 11.0days. The rapid degradation of GPS in surface waters and its practically irreversible sorption on these soils and sediments implies that GPS use in similar agricultural areas is of very low environmental risk. This manuscript also outlines the importance of the presence of photo-sensitizers in waters in the degradation routes of GPS in reservoirs.
草甘膦（GPS）是目前西班牙橄榄作物中使用的一种除草剂，可能会被运送到附近用于人类消费的水库。本研究的目的是研究 GPS 在 Vibora 水库及其支流河水以及周围农业土壤中的水和沉积物中的行为和环境归宿，以评估该水库水污染的风险。GPS 被不同基质吸附的情况如下：水库沉积物的头部（Cabecera）>尾部沉积物（Cola）>土壤>Vibora 沉积物。Cabecera 和 Cola 的沉积物中氧化物（尤其是铁氧化物）含量最高，而 Vibora 沉积物中氧化物含量最低。结果表明，GPS 的最大吸附是由于无定形氧化物和粘土矿物的边缘位点。GPS 的吸附随 pH 值从 8 降至 7 而增加。从所研究的四种土壤中解吸 GPS 的百分比仅在 0.40 至 1.22%之间变化。Cabecera 和 Cola 沉积物的解吸几乎是不可逆的，其值在 0 到 1.1%之间。相比之下，Vibora 沉积物的解吸率约为 20%，可能是由于其粗质地和较低水平的无定形氧化物。对于 Cabecera 和 Cola 地点的水体中草甘膦的耗散，棒状一阶动力学是最佳描述符，对于支流 Vibora 河的水体，简单的一阶动力学是最佳描述符。半衰期（DT50）在 6.3 至 11.0 天之间。GPS 在地表水中的快速降解及其在这些土壤和沉积物上的实际不可逆吸附意味着在类似的农业区域使用 GPS 的环境风险非常低。本文还概述了在水库中 GPS 降解途径中光增感剂在水中存在的重要性。
