三峡库区江段潜在水环境污染风险评价研究

三峡库区的水环境安全不仅关系到库区周边省市用水安全,更与长江流域的生态安全以及整个中国的可持续发展密切相关.基于压力-状态-响应(PSR)模型,综合考虑风险源危险性、风险受体敏感性以及区域环境风险可接受水平等因素构建水环境污染风险分级评价指标体系与量化方法,运用冷热点格局分析等空间统计方法,以行政区为单元综合评价三峡库区潜在水环境污染风险分布状况.结果表明:(1)云阳县风险源数量最多,万州区风险受体数量最多,但重庆主城区及周边地区高风险污染源和高敏感受体分布最为密集,且区域环境风险可接受水平最低.(2)研究区县区级风险源危险性和风险受体敏感性指标统计结果均呈集聚分布格局,热点区域集中在库区上游重庆主城区及周边地区,且该区域风险可接受水平表现为冷点区域,而在其它区域基本呈现为均衡的分布格局,未形成明显的热点或冷点区域.(3)库区水污染高风险江段包括九龙坡区、渝北区、沙坪坝区、渝中区和南岸区等5个县区,中风险江段包括长寿区、北培区、江北区、大渡口区、涪陵区、石柱县和巴东县等7个县区,低风险江段主要分布在库区上游的江津区和库区腹地及下游区域.最后,针对不同区域潜在水污染风险分布特征,从产业优化布局、预警与应急能力建设以及企业污废水处理技术升级等方面提出风险管控的相关建议.

Assessment of Potential Water Pollution Risk in Three Gorges Reservoir

The Three Gorges Project (TGP) is the largest hydroelectric project in the world, whose water environment safety concerns not only on the water supplies safety in the reservoir area, but also on the ecological security of the Yangtze river basin as well as the sustainable development in China. Based on the PSR (Pressure-State-Response) model, the classification assessment index system and quantitative method of water pollution potential risk for Three Gorges Reservoir was constructed, in which the risk sources, the risk receptor and the acceptability of regional environmental risk were considered. The quantitative potential risk zonation maps of water environment pollution at the county level was created with the geo-statistics method, namely the spatial autocorrelation analyzes and the optimized hot spot analysis. The results show that：1) Yunyang County had the largest number of risk sources, while Wanzhou District had the largest number of risk receptors. However, there are the most intensive highly risk sources and highly sensitive receptors in and near Chongqing main City as well as the lowest level of acceptability of regional environmental risk. 2) The statistic of risk sources and receptors of each county showed the clustered distribution patterns. The hot spots were concentrated in and near Chongqing main City located in the upstream of the reservoir area where the acceptability of regional environmental risk showed as cold spot. While the statistical values of other counties were more balanced where there were no focused hot or cold spots areas. 3)The high-risk areas were concentrated in Jiulongpo District, Yubei District, Shapingba District Yuzhong District and Nan'an District; and middle-risk areas were located in 7 Districts including Changshou District, Beipei District, Jiangbei District, Dadukou District, Fuling District, Shizhu County and Badong County; while the low-risk areas were mainly located in Jiangjin District and the lower and middle reaches of the study section. Finally, according to the distribution characteristics of potential water pollution risks in different regions, the corresponding measures were proposed, which included the optimal disposition of industry, the alert and response capability and the technology upgrades of industrial sewage.