辽宁中部城市群城市非点源污染负荷评估

过去几十年我国经历了快速城市化过程，这使得不透水面大幅度增加，导致地表径流和洪峰流量增加，进入水体的污染物增多。城市非点源污染已成为河流水体恶化、生态系统退化的重要原因。在快速城市化过程中，城市群已成为城市化发展的新阶段。位于同一流域的各城市所产生的城市非点源污染导致城市群流域水环境问题越来越突出，成为制约城市群流域可持续发展的关键因素之一。现有的关于城市非点源的研究多集中于城市内部小尺度，对城市群大尺度的研究亟需发展。以位于浑河太子河流域的辽宁中部城市群为例，在沈阳市不同功能区和不同下垫面进行降雨径流采样，基于事件平均浓度(EMC)法和SWMM(Storm Water Management Model)模型相结合的方式，定量评估城市群流域城市非点源污染负荷。研究结果表明：路面径流中城市非点源污染物浓度、负荷量及其单位面积负荷要高于屋面径流和透水面径流。辽宁中部城市群TP、TN、COD、TSS的年均城市非点源污染负荷分别为265.52、852.89、2249.71、192496.74 t/a,重金属Cd、Ni、Pb、Cr、Cu、Zn的年均城市非点源污染负荷分别为347.99、9932....

Assessment of the urban non-point source pollutant loads in the Central Liaoning Urban Agglomeration

Chinese has experienced unprecedented urbanization over the last several decades. Rapid urbanization led to dramatic increasing of urban impervious surfaces which caused dramatically increasing of the surface runoff and peak flows. Excessive runoff volume coupled with increased peak flow can easily wash accumulated dust off impervious urban surfaces and transport it into receiving water bodies, which can seriously affect public health and threaten environmental quality. The urban non-point source (NPS) pollution has been recognized as a critical cause of water quality degradation and aquatic ecosystem deterioration. In the process of Chinese rapid urbanization, the urban agglomeration has become a new characteristic in urbanization development. Most of urban agglomerations are located in the same watershed. The superimposed effects of the urban NPS pollution caused by cities in a same basin became more and more important, playing one of the key factors restricting the sustainable development of urban agglomeration watershed. The urban NPS pollution have been widely studied at a small city or community scale, few attentions have been paid to watershed scales, especially in an urban agglomeration watershed. In this study, the Central Liaoning Urban Agglomeration in the Hun-Taizi River watershed, was chosen as the study case. The rainfall runoff data was observed in different functional zones and underlying surfaces in Shenyang city. The urban NPS pollutant loads were quantitatively estimated by coupling the event mean concentration (EMC) method and the Storm Water Management Model (SWMM). The results indicated that the EMC values, urban NPS pollutant loads and per unit area yield in road runoff were higher than those in roof runoff and pervious surface. The average annual urban NPS pollutant loads of total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD) and total suspended solids (TSS) were 91.01, 280.83, 783.95 and 47212.34 t/a, separately. The average annual urban NPS pollutant loads of cadmium (Cd), nickel (Ni), lead (Pb), chromium (Cr), copper (Cu) and zinc (Zn) were 347.99, 9932.62, 25861.29, 28360.41, 36068.30 and 138840.42 kg/a, separately. Shenyang city had the highest urban NPS pollutant loads while with the lowest per unit area yield of six cities in the Central Liaoning Urban Agglomeration. In this study, a refined approach was presented to accurately estimate the urban NPS pollution by considering the different functional zones, underlying surfaces and rainfall intensities in an urban agglomeration watershed. The method was proposed in this study could provide scientific guidance for urban NPS pollution control and water environment comprehensive management in highly urbanized basins.