Dynamic Variation Of Key Environmental Factors And Evaluation Of Trophic Level In The River Of Dongtan Eco-City

Environment deterioration is one of the most important issues in our world. Eco-city is a significant way to seek harmonious development between human and environment. The water quality in the city is a key part which can influence the success of building an Eco-city.. Tuanwang River, which is an important river located in Chongming Dongtan Eco-city, was chosen to be studied in our article.,By monitering the water quality index in the selected river, dynamic variation of main environmental indicators was analysed and water pollution condition was evaluated. In addition, the sources of main pollutants were determined and the relationship between chlorophyll-a concentration and other water quality factors was analysed.The average flow velocity of Tuanwang River in Eco-city was 31.24cm/s. Thus, Tuanwang River could be recganized as Closed Water System. The average transparency of the river was 42.5, the average DO value was 4.24mg/L, and the average Chl.a concentration was 26.65 mg/m3.The concentration of TN changed between 0.769 mg/L and 4.97 mg/L, and the average value was 1.84mg/L. The concentration of TP was changed between 0.07 mg/L to 0.19 mg/L, and the average value was 0.10 mg/L.The concentration of CODMn was changed between 4.43 mg/L to 7.04 mg/L, and the average value was 5.51mg/L. The main pollution of Tuanwang River is Total Nitrogen, which might be origined from non-point source pollution that produced by nearby farms.By using Comprehensive Nutritive Index method, the water quality in TuanWang River was assessed.The result showed that the river was in light eutrophication.The average value of TLI(∑) is 60.65. Tuanwang River was in Middle eutrophication in April, June, July and August by monthly analysis Tuanwang River is in Middle eutrophication in summer, whereas in the other three seasons of it was in light eutrophication by seasonly analysis.By using modified Carlson Index method, the water quality in TuanWang River was assessed. The result showed that the river was in eutrophication. The average value of TSIM was 69.52. The TSIM value in June, July and August were higher than that in the other months by monthly analysis..Summer was highest season by seasonly analysis.By using Chl.a as the only index, the water quality in TuanWang River was assessed..The average value of chlorophyll-a was 26.65mg/m3, which showed that the river is in eutrophication. In February (2014), Tuanwang River was in mesotrophication, and it was in eutrophication in the other motnths. Tuanwang River was in eutrophication in all the seasons by seasonly analysis.The relationship between chlorophyll-a and envrimental factors was studied. Significantly positive correlations were found between chlorophyll-a concentration and TN, TP and teperature. However, there was no significant correlation between chlorophyll-a and flow velocity, pH value, transparency, DO and CODMn.