地埂式生物质炭可渗透反应墙对紫色土坡耕地中杀虫剂流失的减控机制研究

There has been increasing concern on non-point source environmental pollution of pesticides as a result of their extensive use in farmland ecosystem. In this study, a new in-situ remediation technology "ridged biochar-amended permeable reactive barrier" is proposed and will be explored for controlling insecticide loss from in sloping farmland of purple soil, which has a relatively large macroporosity and is subject to serious soil erosion. Batch and column experiments will be conducted to investigate the sorption and desorption characteristics of insecticides on biochar-amended soil, and to examine the migration of the dissolved and particle-associated forms of insecticides. Optimal kind and application rate of the biochar and required thickness of the permeable reactive barrier will be determined and used for the field sloping farmland plot experiments. Monitoring of insecticide loss from the experimental plots, with emphasis on loss associated with the dissolved and colloidal forms of insecticides, will be performed to test the effectiveness of the ridged biochar-amended permeable reactive barrier. Results of this study will provide a comprehensive evaluation of this new in situ environmental remediation technique regarding its mechanism and feasiblity in field.

农药的广泛和大量使用导致其由农田向水体的流失问题日趋突出，并逐渐成为面源污染研究的新热点。本研究以水土易于流失、大孔隙发育良好的紫色土为研究对象，提出控制坡耕地杀虫剂流失的新型原位拦截技术-"地埂式生物质炭可渗透反应墙"。通过室内批量平衡实验和土柱淋溶实验，揭示生物质炭对紫色土中不同杀虫剂的吸附固定与解吸释放行为及其可溶态、颗粒结合态（含胶体态）迁移性的影响机制，优选生物质炭材料，确定最佳施用量和可渗透反应墙厚度，而后通过野外坡耕地标准小区试验，考查不同坡度下的径流水动力条件对地埂式生物质炭反应渗透墙控制杀虫剂流失的实际效果（尤其关注胶体态农药的流失动态与通量），综合评价"地埂式生物质炭可渗透反应墙"技术的环境效应，为其实际应用的可行性评估提供理论依据。

本项目按照项目计划书开展相关研究工作。以毒性强、土壤吸附性较弱、易迁移的杀虫剂涕灭威及其降解产物涕灭威亚砜及涕灭威砜,以及广谱型农药草甘膦为目标污染物，采用室内批量平衡法与非饱和瞬变流土柱迁移实验法，通过考察生物质炭添加对饱和与非饱和条件下目标农药在紫色土中吸附特性,揭示生物质炭对紫色土中农药的吸附固定与解吸释放行为及迁移性的影响机制。结果发现，生物炭添加可以增加农药在紫色土中的吸附作用并降低污染物解吸作用。在非饱和条件下，水溶性农药涕灭威及其降解产物在老化5%生物炭添加土壤中的阻控作用明显。结合野外模拟污染小区的试验研究，利用坡耕地农药流失的新型原位拦截技术-“地埂式生物质炭可渗透反应墙”评价了在降雨条件下对水溶性易迁移农药在紫色土坡耕地中的出流及土壤残留动态。考查了径流水动力条件对控制农药流失的实际效果，为其实际应用的可行性评估提供理论依据。基于本项目研究结果，共发表相关论文8篇，其中SCI收录论文2篇，EI收录论文4篇，均标注本项目资助，协助培养硕士生3名。