Evaluation and variation trend analysis of eutrophication in Dongping Lake, China

Based on the monitoring data of Dongping Lake in 2012, comprehensive nutrition state index (TLI) method was used to evaluate the state of eutrophication. Eutrophication trend was analyzed from 2008 to 2012 by Spearman's rank correlation coefficient. The results revealed that average nutritional status was mesotropher, with the value of 46.62 in Dongping Lake. Comprehensive nutrition state index of total nitrogen and potassium permanganate were higher than others, and reached light eutropherstatus, witih the values of 59.74, 53.80. According to the correlation between chlorophyll-a, total phosphorus and total nitrogen, the key factor resulting in algae multiply greatly was total phosphorus in Dongping Lake. Moreover, eutrophication was in a downward trend which went from 61.67 to 46.62 in five years, and the eutrophication had been improved in Dongping Lake for the past few years. According to analyze the reason why total phosphorus and potassium permanganate were over standards, the corresponding control measures are proposed to cope with the eutrophication in Dongping Lake.