南水北调中线陕西水源区污染源排放时空变化特征

基于2008—2012年污染源环境统计数据,采用Spearman秩相关系数法等分析南水北调中线陕西水源区污废水及污染物年排放总量变化趋势,借助ArcGIS空间分析功能表征水源区污染源排放的空间分布特征。结果表明:2008—2012年水源区污废水和NH_3-N年排放总量呈显著上升趋势,COD、As、Pb、Cd、Cr和Hg年排放总量呈抛物线型变化,总体上COD、Pb、Cd年排放总量增加,As、Cr和Hg年排放总量降低。水源区污废水及污染物排放量空间差异明显,污废水、COD和NH_3-N排放涉及流域所有区县,其排放量从干流到流域边缘呈现较明显的梯度变化,即位于流域中心或地级市行政中心的区县排放量明显高于位于流域边缘的区县;As、Pb、Cd、Cr和Hg排放量呈现明显的区域分布,主要分布在勉县等8个区县。

The Spatiotemporal Variation Characteristics of Water Pollution Sources in Shaanxi Water Source Area of the Middle Route of South-to-North Water Diversion Project

Based on the environment statistic data from 2008 to 2012, the water pollution sources variation characteristics were analyzed using the Spearman''s rank correlation coefficient method and the emission spatial distribution characteristics of water pollution sources were described using the spatial analysis function of ArcGIS in Shaanxi water source area of the middle route of South-to-North Water Diversion Project. The results indicated that the annual total discharge amounts of waste water and NH₃-N in the region generally increased during 2008-2012, the discharge amounts of COD, As, Pb, Cd, Cr and Hg all showed as a parabolic variation, COD, Pb and Cd generally increased while As, Cr and Hg decreased. Discharge amounts of waste water and pollutants in the region showed obvious differences in spatial distribution, discharge of waste water, COD and NH₃-N involved in all the counties, presented a significantly gradient variation, their discharge amounts of all the counties located in the center of river basin or in the administration center of cities were obviously higher than the counties in their marginal inferior. Discharge amounts of As, Pb, Cd, Cr and Hg displayed an apparently regional distribution, and most emission of heavy metals concentrated in eight countries including Mian County.