三峡库区面源污染的时空特征及EKC分析

在全面核算2008~2018年三峡库区19个区县农业面源污染TN、TP排放量的基础上,分析了其时空变化特征.基于环境库兹涅茨曲线(EKC)理论,构建了基于面板数据的回归模型,探究了库区农业经济发展与面源污染排放强度的演替关系.结果显示,库区农业TN排放波动减少,TP波动增加.各区县的TN和TP年均排放量分别在374~6046t和105~1267t之间.其中,农田化肥与畜禽养殖单元的总产污贡献率达80%以上.库区TN排放强度、畜禽养殖与农村生活单元的TN、TP排放强度均存在显著的"倒U型"EKC关系,目前已跨越拐点.农田化肥TP排放强度、水产养殖与农田固废单元的TN、TP排放强度呈现显著的"直线型"EKC关系,处于与经济同步增长的阶段.建议重点升级农田化肥单元的污染防控能力,以配套推进农村人居环境的改善,促进区域氮磷减排.

Analysis on spatial-temporal characteristics and Environmental Kuznets Curve of non-point source pollution in the Three Gorges Reservoir Area

Total Nitrogen(TN) and total phosphorous(TP) emissions of agricultural non-point source pollution in 19 regions of the Three Gorges Reservoir Area(TGRA) were estimated from 2008 to 2018. Their spatial-temporal variation characteristics were further analyzed. According to Environmental Kuznets Curve (EKC) theory, a regression model based on panel data was constructed to explore the relationship between agricultural economy development and non-point source pollution emission intensity in TGRA. Our study found that TN emissions of agriculture decreased with fluctuation, and TP increased with fluctuation in TGRA. The average annual emissions of TN and TP in each region ranged from 374~6046 tons and 105~1267 tons respectively. Agricultural fertilizer and livestock breeding units contributed to more than 80% of total TN and TP. There were significant "inverted U-shape" EKC relationships to TN emission intensity, TN/TP emission intensity in livestock & poultry breeding unit and rural living unit, indicating that the turning points have been showed in these curves. There were significant "linear" EKC relationships to TP emission intensity in agricultural fertilizer unit, TN/TP emission intensity in aquaculture unit and farmland solid-waste unit, indicating a simultaneous growth with economy. The research finally proposed that agricultural fertilizer unit should upgrade the pollution prevention capacity, so as to improve rural living environment and reduce regional TN and TP emission.