Water Environment Condition Analysis and Evaluation of Nansi Lake

Based on water quality parameters of 15 sites about chlorophyll a(Chl-a),total phosphorus(TP),total nitrogen(TN),transparency(SD) and permanganate index(CODMn)in Nansi Lake and its main inflow rivers,water quality was comprehensively analysised by different periods and monitoring of annual and inter-annual.The results showed that distribution of nitrogen and phosphorus concentration of lake is uneven,distribution of spatial appear non-uniformity.Compared with that in 2004,despite TN and CODMn have fluctuations in 2010,but TP and Chl-a in 2010 was fallen to 65.00% and 60.59%,SD in 2010 increased by 40.62%.Water quality of Nansi Lake and its surrounding river has improved overall,eutrophication situation has grown better,but water quality is farbelow the water quality Ⅲ standard,especially the Nanyang Lake,and some monitoring sites reached to severe eutrophication.Comprehensive analysis and evaluation of water Eutrophication,can provide a theoretical basis to resources protect,the Eastern Route of the South-to-North Water Transfer Project and sustainable development in Nansi Lake.