不同土地利用方式对长三角水源地氮磷流失的影响

太湖流域是我国长江三角洲地区最重要的水源地之一，受到水源地土地利用方式的影响，面源污染依然严重。为了控制氮磷流失，研究以长三角重要水源地安吉赋石水库集水区为研究区，通过野外径流观测探究了不同立地下的氮磷流失特征。结果表明：(1)该地区经济林TN平均流失浓度最大，为3.21 mg/L。TP平均流失浓度表现为经济林(0.13 mg/L)>白茶(0.09 mg/L)>自然地(0.07 mg/L)=次生林(0.07 mg/L)。次生林地能够有效减少氮磷流失。(2)降雨强度和降雨量是影响该地区氮素流失的主要降雨因素。(3)硝态氮和溶解态磷分别是该区氮磷流失的主要形态。(4)氮素污染是影响水质的关键因素，因此在面源污染治理过程中要加强对氮素流失的控制。综上，通过优化水源地土地利用方式，营建结构合理的水源防护林，有助于改善水源地环境，保障饮用水安全。

Effects of Different Land Uses on Nitrogen & Phosphorus Losses of Water Source Areas in Yangtze River Delta

The Taihu Lake Basin is one of the most important water source areas in the Yangtze River Delta region. Due to different land uses in the water sources area, non-point source pollution is still serious. To control the losses of nitrogen(N)and phosphorus(P), we took the Fushi Reservoir catchment in Anji, an important water source in the Taihu Lake Basin, as the test plot, and explored the characteristics of N and P losses with different land uses through field runoff observations. The results showed that:(1)the average loss of TN in economic forests in this region was the largest, which was 3.21 mg/L; the average loss concentration of TP decreased in the order: economic forest(0.13 mg/L)> white tea(0.09 mg/L)>natural land(0.07 mg/L)= secondary forest(0.07 mg/L); clearly, secondary forests could effectively reduce the losses of N and P;(2)rainfall intensity and rainfall volume were the main rainfall factors affecting N loss in this area;(3)nitrate-N and DP were the main forms of N and P loss;(4)N pollution was the key factor that impacted water quality, so it was necessary to strengthen the control of N loss. Obviously, optimizing the land uses of water source areas and constructing well-structured water source shelter forests are helpful to improve the environment of water source areas and ensure drinking water safety.