环渤海地区水污染物排放的时空格局及其驱动因素

Spatiotemporal patterns and driving forces of water pollutant discharge in the Bohai Rim Region

本文基于地级行政单元的水污染物排放和社会经济截面数据,分析环渤海地区水污染物排放的流域特征与时空分异,定量解析环渤海地区及高强度排放聚集区内水污染物排放的驱动因素。研究结果表明:(1)海河流域是环渤海地区纳污量最大、增量最突出的流域,其化学需氧量和氨氮排放分别占区域排放总量的38.94%、39.23%。(2)2005年以来,环渤海地区水污染物高排放区从零星分布向连片分布转变,京津冀、山东半岛、辽中南已成为水污染物高排放区的叠加区域。(3)环渤海地区水污染物排放具有显著空间溢出效应,且空间关联程度呈增大趋势,水污染排放热度呈沿海向内陆递减态势,海河流域热度显著高于其他流域,沿海合作区显著高于内陆协作区;京津冀长期处于热点区和次热区,热区覆盖范围由海河向淮河流域拓展。(4)不同水污染物排放的驱动因素差异显著,对化学需氧量排放而言,经济增长速度、固定资产投资因素呈较强的正向带动,而城镇化水平和工业化程度表现出显著负向影响;对氨氮排放来说,人口规模呈正向带动,固定资产投资和外商直接投资亦有一定正向影响,经济发展水平则呈现显著的抑制作用。

A clear understanding of the spatiotemporal patterns and driving forces of water pollutant discharge has a crucial practical significance for regional joint reduction and prevention of water pollution. Based on the cross-section data of water pollutant discharge and socioeconomic parameters in 67 cities at the prefectural level or above, the spatiotemporal patterns and effects of spatial association of water pollution are quantitatively mea- sured in the Bohai Rim region. Meanwhile, the socioeconomic drivers of water pollutant discharge are estimated by using the econometric model, and some suggestions for the reduction and control of regional water pollution are put forward. The results show that： （1） The Haihe River Basin is the largest and the most prominent water- shed with regard to the total quantity and increment of water pollutants in the Bohai Rim Region. Its COD and NH3-N discharges accounted for 38.94% and 39.23% of the regional total discharges, respectively. （2） The spa- tial pattern of high water pollutant discharge areas has changed greatly, from scattered to continuous distribution since 2005. The Beijing-Tianjin-Hebei region, the Central and Southern Liaoning region, and the Shandong Pen- insula region become the superimposed areas of high discharge zone of COD and NH3-N. （3） Discharges of wa- ter pollutants have significant spatial association effects in the Bohai Rim region, and the significance of water pollutant discharge presents a general decreasing trend from the coastal area to inland areas. Moreover, the Bei- jing-Tianjin-Hebei region has been situated in the hotspots for a long period, and the coverage of hotspot and sub- hotspot areas has expanded continuously from the Beijing-Tianjin-Hebei region to the Haihe River and Huaihe River Basin since 2012. （4） By means of an ordinary least squares （OLS） model estimation, it is demonstrated that there are significant differences in the driving forces of water pollutant discharges. Economic growth rate and fixed asset investment show marked positive correlation with COD discharge, and the level of urbanization and in- dustrialization act as a disincentive to COD discharge. Population size is the primary driving factor of NH3-N dis- charge in the Bohai Rim region, and fixed asset investment and foreign direct investment also show marked posi- tive correlation with NH3-N discharge. There is an appreciable association of high capital investment and high water pollutant discharge in the Bohai Rim region. But high economic development level depresses the discharge of water pollutant, especially in the accumulation zone of high intensity discharge.