Eutrophication Characteristics And Impact Factors Of Three Typical Urban Lakes In Zhejiang And Shanghai

Eutrophication problem has high complexity. The relationship between Different environmental background with different inherent nutrient levels, hydraulic and hydrological conditions and its eutrophication effect has certain regional differences. Characteristics analysis of eutrophication and its impact factor identification can provide decision basis to control and prevent eutrophication and its secondary disasters. This article select Lake Beili,Lake Dishui, and lake YinChu as typical cases to carry out the contrast analysis, identify and compare different impact factors of lake eutrophication, in order to provide reference and reference of similar lake eutrophication control and management.By investigating and collecting related materials, this study shows that the thre lakes have similar characters of natural geography and weather climate. Their service functions are landscape, tourism, and water conservancy. While there are certain differences, such as scale, hydrological condition, water pollution sources between them. These similarities and differences are backgrounds of controingl the eutrophication of lakes, as well as theoretical basis of researching different characteristics and impact factors of eutrophication.This article analyzes eutrophication characteristics of three typical lakes in ZheJiang and Shanghai through three aspects (Lake Sediment, water quality and growth of phytoplankton),then makes water quality evaluation and analyzes the comprehensive index of eutrophication. The results show that, main pollutant of the three lakes is nitrogen and phosphorus nutrient pollution. Sediment organic matter of Lake Beili is relatively higher, sediment total nitrogen content of Lake Dishui is the highest, average sediment total phosphorus content of Lake Beili is relatively higher and show great space differentiation. Water TN concentrations of Lake Beili and Lake Dishui exceed V class, serious pollution, Water TP concentration of Lake Yinchu is highest, in or exceeds V class, Lake Dishui's water quality is in IV class.Chl-a concentration of Lake Yinchu is the highest, then Lake Dishui, Lake Beili is the lowest. Plankton microscopy results also show that eutrophication status of Lake YinChu is the most serious. The TLI of Lake Yinchu is the highest, Lake Dishui is lower, Lake Beili is the lowest. Most of the sampling points in Lake Yinchu had become high levels of eutrophication in the autumn of 2014.It was found that there are some differences as well as common characteristics of main eutrophication impact indicators for urban lakes with various environmental backgrounds via the identification and comparison of eutrophication evaluation indexs of different lakes. In addition to Chlorophyll-a, indicators such as water temperature, nitrogen and phosphorus nutrients, transparency, turbidity played a significant role in the analysis and evaluation of eutrophication. The performance of eutrophication assessment indicators of urban lakes varied with different environmental backgrounds. For example, WT?NO3-N?TN? DO?TU?SAL?TP and Chl-a were principal impact indexs for Beili Lake. For Yinzhu lake, TN?NO3-N? SD?TP?WT and Chl-a were the cardinal impact indicators. While for Dishui Lake, indicators such as DO?TSS?WT?SAL?TN?Chl-a and PP played a major role.There's great difference of phytoplankton to nitrogen and phosphorus nutrient responses in different environmental background. For example, Beili Lake is a typical phosphorus-limited lake, although the concentration of nitrogen nutrient is high, Chl-a and nitrogen nutrient present negative correlation, Chl-a and total phosphorus appear very significant positive correlation, so we should pay attention to phosphorus emissions control when taking eutrophication control. Chl-a in Yinchu Lake is more sensitive to nitrogen and phosphorus, so attentions should be paid to control nitrogen and phosphorus nutrient input and its ratio. In Dishui Lake, there's significantly correlation between Chl-a and particle state phosphorus, and there's no obvious correlation with the total nitrogen and total phosphorus, particle state phosphorus pollution control should be paid attention to.This study showa that Climate and weather condition has great impacts on the eutrophication of the three lakes in Zhejiang and Shanghai. Weather variations should be paid great attention to when taking eutrophication control measures. Phosphorus control is the key of the eutrophication governance in Lake Beili and Lake Dishui. Suggestions are to strengthen on the non-point source pollution in ecological intercept and strengthen management of aquatic plants. While eutrophication control of Lake Yinchu should pay attention to both Nitrogen control and Phosphorus control. Suggestions are to limit the number visitors of the lake, strengthen the ground cleaning and implement sediment dredging.