中国农业面源污染形势估计及控制对策 Ⅲ.中国农业面源污染控制中存在问题分析

 对中国农业面源污染控制中存在的主要问题进行了剖析。分析指出,中国各主要流域的面源污染控制仍然有较大误区,最主要的问题是没有对点源和面源污染进行分类控制。目前即使在农业面源污染已成为水体污染主要原因的流域,仍以河口、河道地带等末端控制工程建设为主。由于没有遵循农业面源污染控制的基本原则:整个流域统一布局,充分考虑当地农村经济条件和现有种植结构,最大限度照顾农民利益,在源头上对不同类型的污染实行总量控制,因此许多地区高氮、磷养分用量的菜果花农田面积目前仍在大幅度增长,对今后流域治污造成更大难度。根据中国现状,目

Estimation of Agricultural Non-Point Source Pollution in China and the Alleviating Strategies Ⅲ.A Review of Policies and Practices for Agricultural Non-Point Source Pollution Control in China

Current policies and projects implemented for controlling water pollution in China were reviewed. The mainproblem is that the controlling prosecution has been mainly concentrated on end-control engineering projects such asestablishment of sewage farm and artificially-built or reclaimed wetland at bayou or watercourse, even in the watershedswhere agriculture is the leading contributor to water eutrophication of the water systems. Because of lacking of source-control policies and technologies for reducing pollutants resulting from agricultural activities, cropping areas for vegetable,fruit tree and flower crops with extremely high nitrogen and phosphorus fertilization increased rapidly in sensitive regionsof watershed. The continuing increase of fertilizer use and animal breeding in rural area of important watersheds makes iteven more difficult in future to restore already heavily eutrophic aquatic ecosystems. To solve the problems, it was suggestedthat the proper regulations to confine environment-unfriendly agricultural activities should be established and implementedin different watersheds as soon as possible. The conventional techniques should be replaced by more environment-friendlyalternatives. Since changes of land use form and technologies might result in income losses of farmers in rural region,effectiveness of such source-control policies depends greatly on that the implemented regulations and techniques shouldbe approved with high financial and social feasibility. To improve efficiency of the source-control, detailed research worksto understand main reasons and generating mechanisms of non-point source pollution from agriculture should be carriedout in watersheds. According to local climate, hydrological, geological, topological, soil and agricultural production conditions,water protection zones of different grades should be defined. Corresponding to the sensitivities of different zones toaquatic ecosystem, the related technical standards for land use form, treating excrements from animal stall, fertilizing,plowing, pesticide spraying, irrigation and rotation should be draw. In watersheds with heavy agricultural non-point sourcepollution, subsidy to farmers might be necessary in order to encourage a wide-spread application of environment-friendlyalternatives in the whole watershed.