不同土地利用对流域土壤侵蚀和氮、磷流失的影响

水土流失是非点源污染主要的发生形式,而不同土地利用(植被覆盖)对土壤侵蚀及其氮、磷的流失起着决定性的作用。本文通过在福建省九龙江流域内选取典型小流域来研究不同植被类型与土壤侵蚀和氮、磷流失的关系。结果表明,不同植被覆盖的典型小流域降雨径流中悬浮泥沙、氮、磷的流失依次为:坡地果园>水稻田>半人工果林>天然次生林;典型小流域降雨径流流失的悬浮泥沙量、氮、磷流失量与植被覆盖度和降雨量成反比;而且氮的主要流失形态为溶解态,磷的流失形态主要为泥沙结合态。

An Experimental Research on Soil Erosion and Nitrogen,Phosphorus Losses Under Different Vegetation Covers

Soil e ro sion is an important formof nonpoint source pollutions.Different patters of lan d use may have signi ficant effects on soil erosion and results in losses of nit rogen and phosphorus.This work was conducted to determine relationship between different vegetation covers with sediments an d nitrogen and phosphorus losses .We selected four small representative watersheds in Jiulong River to conduct t he present researc h.From May to August of 2003,series o f water samples w ere collected from 4sub-watershed drainage outlets in each rainfall event,an d in the meantime,flow rate of the rum off was also measured.Total nitrogen(T N),total dissolved nitrogen(TDN),total phosphorus(TP),total dissolved ph osphorus(TDP)and suspend sediment (SS)were measured for the samples.The res ults obtained sh owed as follows:the order of sedimen t yields and losses of ni trogen and phosphorus in the small watersheds was in an order:orchard>>farm> manpower forest>natural forest.And the more the vegetation cove rs,the smalle r the nitrogen and phosphorus losses.Sediments and runoff by which nutrie nts w ere lost had the same trend durin g the rainfall period.Total dissolved nitroge n(TDN)was the major form of nitrogen loss in runoff and total particulate phos ph orus(TPP)was the major form of phosphorus loss in runoff.