江苏污水处理差别定价政策对地表水质的影响——基于合成控制法的研究

近年来，我国工业污水排放量持续增长、水污染事件频发，对生态环境和居民健康造成严重危害。为扭转这一局面，各级政府相继出台众多环保政策。利用2013~2016年周度省级面板数据，选取高锰酸盐(COD_Mn)、溶解氧(DO)、氨氮(NH₃)等3类单项指标，基于合成控制法(SCM) 评价江苏省污水处理差别定价政策的效果，并借助熵权法构建综合指标以评价其综合效应。研究发现：政策实施后，江苏省地表水质整体上取得明显改善；溶解氧指标提高，表明地表水体自净能力显著提升；但由于不易监管，以高锰酸盐和氨氮衡量的地表水体富营养化反而有所恶化。为确保实现预期目标，政策制定及动态调整必须保证激励约束相容。

Influence of the Differential Treatment Charge Policy about the Sewage Water in Jiangsu Province: Based on the Synthetic Control Method

In recent years, the sewage emission in China has increased gradually and the water pollution incident happened frequently, causing serious damage to the ecological environment and residents’ health. To reverse the situation, governments at different levels have introduced various environmental protection policies. We collected weekly provincial panel data from 2013 to 2016, and three water pollution indicators including permanganate (COD_Mn), dissolved oxygen (DO) and ammonia nitrogen (NH₃) are selected. Then, differential treatment charge policy about the sewage water in Jiangsu Province were evaluated basing on the synthetic control method(SCM), and a comprehensive indicator was constructed using the entropy weight method to evaluate the comprehensive policy effect. The main findings are: the policy has obviously improved the overall surface water quality; dissolved oxygen (DO) indicator has been improved, indicating that the self-purification ability of the surface water has been improved; however, it made eutrophication increasingly serious which was measured by permanganate(COD_Mn) and ammonia nitrogen (NH₃)indicator owing to supervising difficulty. For achieving effective regulation, policy decision and its dynamic adjustment must comply with constraints of “Incentive Compatibility”.