三峡库区面源污染防控BMPs框架体系研究

BMP Framework for Nonpoint Source Pollution Control in the Three Gorges Reservoir Area

三峡库区面源污染具有地域范围大、随机性强、成因复杂的特点,形成过程受地理、气候、土壤等多种因素影响,监测、控制、处理和管理难度较大。构建三峡库区面源污染防控最佳管理措施框架体系,从源头控制、迁移途径阻截、末端治理三方面控制三峡库区面源污染。基于源头控制的最佳管理措施:根据区域现场条件,选择"坡改梯"或"大横坡+小顺坡"坡耕地有限顺坡耕作技术模式;进一步推广植物篱种植模式;大范围推广粮食作物的平衡施肥技术,推广使用高效低毒低残留非水溶性农药。基于迁移途径阻截的最佳管理措施:在适生植物筛选及淹没实验研究基础上,进行消落带湿地生态系统培育;开展库岸植被缓冲带工程建设和水塘-湿地工程建设,拦截、净化入库污染物,兼以改善景观;实施植被过滤带防护性工程,控制N、P等养分流失,保护生态环境。基于末端治理的最佳管理措施:按照成本低廉、效果稳定、技术操作简单的原则,可考虑生物处理+人工湿地的组合工艺处理典型农村的生活污水;在前置水库周边建设沿岸生态防护林、湿地及多塘系统、敞水区动植物措施等生态工程;遵循减量化、资源化、无害化原则,对畜禽养殖业进行科学规划,合理布局;发展养殖业和种植业相结合,既可消除畜禽养殖业产生的负面效应,又可减少化肥施用量。

Nonpoint source（NPS） pollution is the primary source of pollutants to the Three Gorges Reservoir,accounting for 70.8 %,60.6 % and 74.9 % of the total CODMn,N and P loads.Water pollution in Three Gorges Reservoir is affected by the geography,climate and soil.Monitoring,control,and management of nonpoint source pollution in the Three Gorges Reservoir area is difficult as the pollution sources are complex and highly random,with a huge range of effects.Based on a comprehensive analysis of technical countermeasures and the local situation,a framework of best management practices（BMPs） has been developed for controlling nonpoint source pollution and includes three approaches：source control,path interruption and terminal treatment.Practices for source control include low tillage cultivation in highly sloped farmland,planting hedgerows as buffer strips,fertilization using nutrient management planning,and efficient utilization of pesticides selected for low toxicity,low residuals and low water solubility.Practices selected for path interruption include wetland construction in the water fluctuation zone（based on plant screening and submergence experiments）,reservoir bank vegetation projects and pond-wetland projects that effectively intercept and remove pollutants flowing into the reservoir while improving the riparian landscape.Additionally,vegetated filter strips can be developed to intercept N and P and reduce nutrient loading.Terminal treatment methods include biological treatment combined with artificial wetland treatment for rural domestic sewage,ecological restoration projects（near-shore forests,wetlands,etc.） and scientific management of livestock and poultry.Prospects for integrating management with technological approaches to control nonpoint source pollution in the Three Gorges Reservoir area were also reviewed in this paper.In the future,the focus should be on optimizing BMPs for the Three Gorges Reservoir area and strengthening research on the regulatory framework for nonpoint source pollution control.