经济集聚、收入差距对水污染影响的时空分析——基于中介效应和动态空间门槛效应检验

本研究将经济集聚、收入差距和化学需氧量（COD）排放强度纳入统一框架下,构建时空双向固定效应的动态空间杜宾模型（DSDM）和门槛空间动态面板模型（SDPTM）,通过中国2011-2020年省级面板数据实证检验,考察经济集聚和收入差距对COD排放强度的影响机制。研究发现：①经济集聚呈“先促排、后减排”的倒“U”形特征,具有本地空间减排效应和空间溢出减排效应;②收入差距呈非线性的倒“N”形特征,具有本地空间减排效应,经济集聚在收入差距对COD排放的影响中存在门槛效应,当经济集聚超过门槛值1.1164时,收入差距的促排和减排效应均明显增强;③收入差距呈倒“N”形特征,具有空间溢出减排效应,且收入差距的长期空间溢出减排效应明显减弱;④收入差距在经济集聚时对COD排放强度的影响中起部分中介效应;⑤COD排放强度具有显著的时间和空间路径依赖性,经济集聚对COD排放的空间依赖特征的影响具有显著的区域异质性。

Spatiotemporal Analysis of the Impact of Economic Agglomeration and Income Gap on Water Pollution-Empirical Test Based on Mediation Effect and Dynamic Spatial Threshold Effect

To conduct empirical investigations of the influential mechanism of economic agglomeration and income gap on COD emission, this paper integrates economic agglomeration, income gap and COD emission elements into an unified framework and constructs a dynamic spatial Dubin model (DSDM) with time-space two-way fixed effects and a spatial dynamic panel threshold model using China''s provincial panel data from 2011 to 2020. The results show that economic agglomeration has "inverted U-shaped" local COD emission reduction effect and spatial spillover emission reduction effect that promoting growth first and then inhibiting. Income gap has non-linear "inverted N-shaped" local emission reduction effect and economic agglomeration has threshold effect in the impact of income gap on COD emission. When economic agglomeration exceeds the threshold value of 1.1164, the emission promotion and emission reduction effects of income gap are significantly enhanced. Income gap has "inverted N-shaped" spatial spillover emission reduction effect. But the long-term spatial spillover emission reduction effect of income gap is significantly weakened. Income gap plays a partial mediating role in the impact of economic agglomeration on COD emission. COD emission bears significant time and space path-dependence characteristics, and the impact of economic agglomeration on the spatial path-dependence characteristic of COD emission presents pronounced regional heterogeneity.