title: Use of Fe/Al drinking water treatment residuals as amendments for enhancing the retention capacity of glyphosate in agricultural soils.
abstract: Fe/Al drinking water treatment residuals (WTRs), ubiquitous and non-hazardous by-products of drinking water purification, are cost-effective adsorbents for glyphosate. Given that repeated glyphosate applications could significantly decrease glyphosate retention by soils and that the adsorbed glyphosate is potentially mobile, high sorption capacity and stability of glyphosate in agricultural soils are needed to prevent pollution of water by glyphosate. Therefore, we investigated the feasibility of reusing Fe/Al WTR as a soil amendment to enhance the retention capacity of glyphosate in two agricultural soils. The results of batch experiments showed that the Fe/Al WTR amendment significantly enhanced the glyphosate sorption capacity of both soils (p<0.001). Up to 30% of the previously adsorbed glyphosate desorbed from the non-amended soils, and the Fe/Al WTR amendment effectively decreased the proportion of glyphosate desorbed. Fractionation analyses further demonstrated that glyphosate adsorbed to non-amended soils was primarily retained in the readily labile fraction (NaHCO3-glyphosate). The WTR amendment significantly increased the relative proportion of the moderately labile fraction (HCl-glyphosate) and concomitantly reduced that of the NaHCO3-glyphosate, hence reducing the potential for the release of soil-adsorbed glyphosate into the aqueous phase. Furthermore, Fe/Al WTR amendment minimized the inhibitory effect of increasing solution pH on glyphosate sorption by soils and mitigated the effects of increasing solution ionic strength. The present results indicate that Fe/Al WTR is suitable for use as a soil amendment to prevent glyphosate pollution of aquatic ecosystems by enhancing the glyphosate retention capacity in soils.
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: zyy@mail.bnu.edu.cn.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: School of Agriculture and Food Sciences, University of Queensland, St Lucia, Queensland 4072, Australia.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Wendling
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Changhui
authors.initials: C
authors.lastname: Wang
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: yspei@bnu.edu.cn.
authors.forename: Yuansheng
authors.initials: Y
authors.lastname: Pei
mesh_terms: D000327:Adsorption; D000383:Agriculture / Q000379:methods*; D000535:Aluminum / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D006540:Herbicides / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D018508:Water Purification; D000097797:Glyphosate
chemical_list: D000535:Aluminum; D005998:Glycine; D006540:Herbicides; D007501:Iron; D012987:Soil; D000097797:Glyphosate
keywords: Fe/Al drinking water treatment residuals; Glyphosate; Soil amendment; Sorption capacity; Stability