Distribution mode and environmental risk of POP pesticides such as endosulfan under the agricultural practice of straw incorporating

Abstract

The practice of incorporating post-harvest crop waste is widely used because it maintains soil fertility and avoids environmental pollution from straw burning. However, the practice of straw incorporation may also retain the pesticides that are applied to crop plants, which may pose a potential long term risk to local and regional environments if the applied pesticide is a Persistent, Bioaccumulative, and Toxic (PBT) substance or a Persistent Organic Pollutant (POP). Here we investigate the influence of the "receiving-retention-release" route on the distribution of a POP pesticide (endosulfan) and the associated environmental risk among different environmental compartments. Our study indicates that most endosulfan enters the atmosphere (φ_atmosphere = 64.5-72.5%), which is dominated by the indirect route of volatilization from crop plants (φ_{atmosphere, indirect} = 54.7-70.3%). In contrast, soil releases are minor (φ_soil = 10.8-20.5%), and are dominated by direct release during application (φ_{soil, direct} = 8.0-18.0%). Under the practice of straw incorporation, the use of endosulfan posed an environmental risk to agricultural soil. In addition, the atmospheric deposition of endosulfan also posed an environmental risk to sediment. The study highlights the significance of the "receiving-retention-release" route by crop plants in determining the fate of POP pesticides associated with straw incorporation; hence complementing the current methodology for assessing the environmental risk of these compounds.

Keywords: Endosulfan; Environmental risk assessment; Straw incorporation; “Receiving-retention-release” route.