流溪河水库流域非点源溶解态氮磷污染负荷估算

流溪河水库作为广州市最重要的水源地之一,其水环境质量受到广泛关注.利用基于SCS模型的污染负荷输出,对流溪河水库流域非点源溶解态氮磷污染负荷进行估算.结果表明:流域非点源溶解态氮污染负荷为384.31 t/a,溶解态磷污染负荷为20.68 t/a.其中氮贡献最大的为林地,占50.93%;其次为园地,占18.10%.磷贡献最大的亦为林地,占49.22%;其次为旱地,占15.85%.溶解态氮单位面积污染负荷道路最高,为50.57 kg/(hm2.a);其次是水田,为33.60kg/(hm2.a).而溶解态磷单位面积污染负荷最大是水田,为3.43 kg/(hm2.a);其次是道路,为3.19 kg/(hm2.a).与水库流域颗粒态氮磷污染负荷比较表明,溶解态氮大于颗粒态氮,氮以溶解态迁移为主;溶解态磷则小于颗粒态磷,但由于颗粒态磷易随泥沙受阻或沉降,溶解态磷对水库水质的影响依然是总磷关注的重点.

Estimation of Non-Point Soluble Nitrogen and Phosphorus Pollutant Loads in the Drainage Area of Liuxi River Reservoir

The Liuxi River Reservoir is one of the most important drinking water sources in Guangzhou.The water quality of the reservoir widely attracts the public’s attention.This article evaluated the non-point soluble N and P pollutant loads of the drainage area of the reservoir by using the pollutant loads’output expression based on the SCS model.Results indicated that the pollutant loads of the non-point soluble N and P of the drainage area were 384.31 t /a and 20.68 t /a respectively.Forest land contributed most to the pollutant load of soluble N,with a percentage of 50.93%.Orchards came next with a percentage of 18.10%.As for soluble P,forest land was still the greatest contributor with a percentage of 49.22%,followed by unirrigated land with a percentage of 15.85%.In the case of non-point soluble N pollutant load per area by land use type,traffic roads came first with 50.57 kg /(hm2.a),followed by paddy fields with 33.60 kg /(hm2.a).As for soluble P,paddy fields came first with 3.43 kg /(hm2.a),followed by traffic roads with 3.19 kg /(hm2.a).As compared with particulate N and P pollutant loads,soluble N was greater than particulate N,and was the main form of N migration,while soluble P was less than particulate P.However,because particulate P is easy to be deposited or blocked,soluble P is still the focus of attention in terms of the Liuxi River Reservoir’s TP.