经济集聚对区域水污染物排放的影响及溢出效应

基于化学需氧量和氨氮排放数据集,构建影响因素计量模型,探讨经济集聚同水污染物排放的影响效应及其在不同规模城镇下影响程度的差异性,采取双变量空间自相关解析中国经济集聚对水污染物排放的溢出效应,以期为促进经济集聚与污染减排良性互动提供参考。结论如下:(1)从全国总体样本来看,经济集聚能有效降低区域水污染排放强度,经济集聚度每增长1个百分点,化学需氧量和氨氮排放将分别减少0.491%和0.166%;(2)经济集聚对中小城市水污染排放的减排效应更为突出,在化学需氧量估计模型中,中等城市、小城市样本的经济集聚度弹性系数分别为-0.679、-0.546,而大城市及特大城市样本仅为-0.252;(3)经济集聚同水污染物排放的空间溢出效应显著,且呈现高集聚-高排放、低集聚-低排放、低集聚-高排放等空间关联模式,其中,高集聚-高排放区从京津冀向山东半岛绵延分布,还包括哈长城市群、苏北和苏中、长株潭、珠三角等地区。政策启示包括:积极培育中小城市并发挥其经济聚集的减排效应,促进生产技术更新和扩散,提高能源利用效率和环保投入;合理控制大城市经济与人口规模,加快产业结构调整和落后产能淘汰,强化环境规制以防止"污染避难所"效应;遏制经济集聚对水污染物排放的溢出效应,重点推进高集聚-高排放区联防联控和流域共治。

Impact of economic agglomeration on regional water pollutant emissions and its spillover effects

Based on the database of COD and NH₃-N emissions from 339 cities at prefecture level in China, this paper explores the impact of economic agglomeration on regional water pollutant emissions and the differences in the impact levels between different city-size by using the econometric model. Meanwhile, a bivariate spatial autocorrelation method is adopted to analyze the spillover effect of economic agglomeration on water pollutant emissions, which provides a reference for making a benign interactive countermeasure to promote economic agglomeration and pollution mitigation. The results show that: according to the whole sample, economic agglomeration can effectively reduce the intensity of the regional water pollutant emissions. The degree of economic agglomeration increases by 1%, and the COD and NH₃-N emissions will decrease by 0.491% and 0.166% respectively. Compared with the large cities and mega-cities, economic agglomerations have more prominent reduction effects on water pollutant in small and medium-sized cities. Economic agglomeration and water pollutant discharge have shown significant spatial spillover effects, and present spatial agglomeration patterns of high agglomeration-high emission, low agglomeration-low emission, and low agglomeration-high emission. High agglomeration-high emission areas are located from Beijing-Tianjin-Hebei region to the Shandong Peninsula, as well as other highly urbanized area such as Harbin-Changchun, the Yangtze River Delta, the Pearl River Delta and Changsha-Zhuzhou-Xiangtan. Policy implications and suggestions include: actively nurturing small and medium-sized cities, exerting significant reduction effects of economic agglomeration, promoting technological upgrade and diffusion of production technologies, improving energy efficiency and environmental protection input; rationally controlling the economic and population size of large cities and mega-cities, improving environmental regulations to prevent "Pollution Haven" effects, and accelerating industrial restructuring and outdated production capacity to eliminate and strictly control over-standard and over-total emissions; reducing the negative externalities of economic agglomeration, with a focus on promoting joint prevention and basin governance of high agglomeration-high emission area.