Ecosystem Health Diagnosis Of Rivers(Nanfei River,Zhegao River,Fengle River,Hangbu River) Into The Chaohu Lake

Chaohu Lake is one of the largest five freshwater lakes in China.It’s basin has always been with concentration of population and intensive agricultural activities.With the development of regional economy,the pollution of Chaohu Lake become increasingly serious.The water source of Chaohu Lake mainly depends on the inflow river,so the research of environment of inflow river can be used as a reference for the environmental management of Chaohu Lake.The objects of research in this paper are Nanfei river,Zhegao river,Fengle river and Hangbu river which are the main inflow river of Chaohu Lake.The study analyzed the indexes that contained overlying water,sediment physical,chemical properties,sediment heavy metal,composition of vascular plants,the community of plant in different flood seasons.The ecosystem health of main rivers into the lake that included Nanfei river,Zhegao river,Fengle river and Hangbu river was comprehensive assessed.The results showed that:(1)The contents of total phosphorus(TP)and total nitrogen(TN)of Nanfei river,Zhegao river,Fengle river and Hangbu river are varous among the different flood seasons,the contents were shown as:dry season>level period>flood season.The main pollution factors of overlying water were TP and TN,followed by CODMn.The pollution of river:Nanfei River>Zhegao River>Hangbu-Fengle river.TN and TP of Nanfei river were seriously pollution,and total nitrogen exceed the standard in wide range of location.The value of CODMn of the Nanfei River is serious,and the highest concentration of pollutants was in dry season.(2)The results of accumulation index and potential ecological risk index showed that the pollution of Nanfei River was more serious.The evaluation results of accumulation index and potential ecological risk index method was indicated that Cd was a major contribution to the ecological risk factors.The concentration of Cd in the survey sample ranged between 64.53 and 862.33,therefore it was in a larger ecological risk.(3)There are 102 species of vascular plants in the rivers of the lake,which belong to 39 families.Gramineae,Polygonaceae,Cyperaceae,Compositae,Leguminosae dominant species composition of community;There were 3 benthic animal classes,10 families and 15 species in giant mollusk,including bellamyaaeruginosa(Bellamya aeruginosa)as the dominant species.(4)The inflow river’s health status in "health" "disease" and "poor" in"sub-health" sampling points are 8,7,11 and 14,respectively.They respectively accounted for 17.5%,27.5%,35.0%,20.0%of the total count of survey sections.The health of river ecosystem of Nanfei river and Zhegao river were more serious than the health of river ecosystem of Fengle-Hangbu river.