流溪河水库流域非点源溶解态氮磷污染负荷估算

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

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.

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.