无锡市不同土地利用类型非点源污染负荷变化分析

以非点源污染严重的无锡市为研究区,在RS和GIS技术的支持下,采用SCS曲线方程和USLE方程估算了不同土地利用类型的非点源污染负荷,进而分析不同土地利用类型变化带来的非点源污染负荷贡献率的变化.结果表明:①无锡市2000 ～2008年总氮(TN)负荷增幅为4.75％,总磷(TP)负荷增幅为3.28％.②不同土地利用类型对非点源污染负荷总量和单位面积的贡献率存在差异,农用地和建设用地对污染负荷贡献率均在90％以上;从单位面积污染贡献上看,对TN贡献率较大的土地利用类型依次为农村建设用地、农用地及城镇建设用地,对TP贡献率较大的土地利用类型依次为农村建设用地、农用地和林地.③不同土地利用类型对非点源污染负荷的贡献率也在发生变化,城镇建设用地对TN和TP的贡献率变化最为突出,分别上升了21％和17.4％;农村建设用地的TN和TP贡献率分别下降了22.3％和19.9％;农用地贡献略为减少;林地、荒地和水域贡献率略为上升.

Changes of non-point pollution loads of different land-use types in Wuxi city

Supported by RS and GIS technology, non-point source pollution loads of different land use types in Wuxi city, which have problems of serious non-point source pollution, were estimated using SCS (soil conservation service) curve equation and USLE (unversal soil loss equation) equation. The changes of contribution rates of different land use types to total non-point source pollution load were analyzed. The results were as follows. Firstly, from year 2000 to 2008, total nitrogen load and total phosphorus load increased 4.75%, 3.28% correspondingly. Secondly, different land use types had different contributions to non-point source pollution load in total and per area. Contribution rates of farmland and construction land were more than 90% in total; while in per area, successively, rural construction land, farmland and urban construction land contributed mostly to total nitrogen load, but rural construction land, farmland and woodland to total phosphorus load. Finally, contribution rates of different land use types to total non-point source pollution load had been changing. Urban construction land was the most outstanding, which contribution rates rose by 21% and 17.4% to the total nitrogen load and total phosphorus load, respectively, while those of rural construction land decreased by 22.3% and 19.9% correspondingly ; farmland decreased slightly, and woodland, wasteland and water rose slightly.