中国地表水水质变化趋势及治理政策应对

Trends in China’s surface water quality and control policy solutions

中国水污染治理的严峻性不言而喻,该研究描述了2004—2022年中国地表水水质变化趋势,总结了“五年规划”对水污染治理的要求并分析其治理效果,为未来中国地表水污染治理提供参考。总结回顾了“五年规划”中水污染治理的减排目标和重点流域,发现“九五”计划以来中国环境治理在水污染治理方面提出越来越细致、严格的要求的同时还不断扩大重点流域的范畴。进一步,利用2004—2017年《全国主要流域重点断面水质自动监测周报》以及2018—2022年《全国地表水水质月报》,研究了中国水质等级和各项污染指标的年度变化趋势,发现中国水环境治理成效显著,地表水环境质量整体呈上升趋势,劣Ⅴ类水比例下降明显,其中北方地区河流水质改善尤为明显,而南方地区河流水质始终处于相对较好的水平。从四项污染指标的具体数值来看,各项污染指标均在改善,但高锰酸盐指数仍为多数断面的主要污染指标,因此需要进一步加强对来自工业废水和生活污水的点源排放以及来自农业的面源排放的管控。此外,不同流域的污染指标变化趋势以及事件研究法的结果表明,“五年规划”对改善地表水溶解氧、高锰酸盐指数和氨氮浓度起到了积极的作用。但是,当水质指标达到较高水平后可能面临反弹,加之减排边际成本的提高和监测难度的增加,进一步降低污染物浓度、改善水体质量将面临更大的困难和挑战。

The severity of China’s water pollution control is obvious.To provide a reference for the control of surface water pollution in China,this paper first described the trends in China’s surface water quality from 2004 to 2022 and summarized the requirements of China’s‘Five-Year Plans’for water pollution control and the corresponding control effects.It then reviewed the emission reduction targets and key river basins for water pollution control in the‘Five-Year Plans’and found that since the‘9th Five-Year Plan,’China’s environmental governance had put forward more detailed and strict requirements for water pollution control and expanded the management scope of major river basins.Furthermore,using the National Weekly Report on Automatic Monitoring of Water Quality in Key Sec⁃tions of Major River Basins from 2004 to 2017 and the National Monthly Report of Surface Water Quality from 2018 to 2022 to study the annual trends of water quality grades and pollution indicators in China,this study found that China’s water environment governance achieved remarkable results:the overall surface water quality was on the rise,and the proportion of water inferior to Class V dropped significantly.The water quality of rivers in the northern region improved significantly,while that in the southern region maintained a relatively good level.In terms of the specific values of the four pollution indicators,all pollution indicators were improving,but the permanganate index was still the main pollution indicator in most sections,so it is necessary to further strengthen the control of point source discharge of industrial wastewater and domestic sewage as well as non-point source discharge from agriculture.In addition,the trends of pollution indicators in different river basins and the results of the event study method showed that the‘Five-Year Plans’played a positive role in improving the dissolved oxygen,permanganate index,and ammonia nitrogen concentration of surface water.However,a rebound may happen when the water quality indicators reach a high level.With the increase in the marginal cost of emission reduction and monitoring difficulties,greater difficulties and challenges would appear in the process of further reducing pollutant concentration and improving water quality.