Study on Trophic State Assessment and Its Driving Factors of Small or Medium Size Lakes in Jangxi Province

Monitoring data of water quality for 25 small and medium lakes in Jiangxi Province in 2010 were collected. The trophic state of these lakes was evaluated by comprehensive eutrophication state index method, and the driving factors of the eutrophic lakes studied applying the principal component analysis (PCA). The results demonstrated that the trophic states of all the lakes were in mesotropher, 8 among which were lightly eutrophicated. The driving factors of the water eutrophication could be divided into 4 groups. The pH value, total nitrogen and nitrate were the most important indexes for water eutrophication in Jiangxi Province; the phosphorus-containing nutrient indexes such as TP and DP belonged to the second group; the natural characteristic indexes such as water depth and temperature were in the third group; and the biological and organic compounds indexes such as Chl-a and COD_Mn contributed the lest for water eutrophication in the studied lakes.