The Quality Analysis And Pollution Control Of The Water Environment Of Tangxun Lake

As the largest downtown lake in China,Tangxun Lake's water pollution has attracted much attention.The existing research is aimed at one aspect of Tangxun Lake pollution,and the data,sampling time and research methods are not uniform.The conclusions are different and can not grasp the water environment pollution of Tangxun Lake comprehensively and systematically.This study sums up the research achievements of predecessors,and then,under the existing conditions,the water quality status,eutrophic status and sediment pollution of Tangxun Lake were analyzed and evaluated comprehensively to explore its pollutant sources and main pollution problems.According to the main pollution index of Tangxun Lake,the mathematical model is established to predict the future water quality to understand the trend.On the basis of this,the water quality model was established by combining the amount of pollutants into the lake and the water function regionalization to calculate the water environment capacity.And then put forward the total emission control plan of Tangxun Lake and the related control measures,so as to lay the foundation for water pollution control and water environment planning and management of Tangxun Lake.Research shows that:?1?The total pollution load of COD_Cr?NH₃-N?TN and TP in the Tangxun Lake Basin was 4434.51 t/a,769.38 t/a,1017.03 t/a and 69.35 t/a,respectively,in 2014.Furthermore,the tailwater of the sewage treatment plant and the surface runoff are the main source of pollutants in the Tangxun Lake and the primary reduction of total control.?2?The main exceeding standard factors for Tangxun lake are COD_Cr,TN and TP.Inner Lake water quality is significantly inferior to the outer lake,and the evaluation grade of water quality of inner lake and outer lake is class?and?respectively.Compared with fuzzy comprehensive evaluation method and gray clustering method,comprehensive water quality dentification index method is more suitable for water quality evaluation of Tangxun Lake.?3?There are no obvious changes with the seasons in the eutrophic status of inner lake and outer lake.In general,eutrophic status was moderately eutrophic,with mild eutrophication in individual months.?4?GM?1,1?prediction model can be used to predict the water quality of Tangxun Lake.The concentrations of COD_Cr,NH₃-N,TN and TP show a upward trend with a slightly downward trend of COD_Mn concentration in the period from2006 to 2020,and the concentrations of the inner lake raise faster than that of the outer lake.Among them,the concentrations of NH₃-N and TN in the inner lake have the fastest growth rate.?5?The concentrations of TOC,TN and TP in the sediment show a decreasing trend with the increase of the depth,and the pollution of nutrient salts in the sediment of the outer lake is more serious than that of the inner lake,among which TOC and TN are mild pollution and severe pollution respectively.?6?Six kinds of heavy metal elements have a certain degree of pollution,and the overall pollution degree is:Cd>As>Zn>Cu>Cr>Pb,the ecological hazard degree of heavy metal in Tangxun Lake according to the ecological factors is:Cd>As>Pb>Cu>Cr>Zn.?7?The TN and TP in the sediment of the Tangxun Lake may come from the bait during the aquaculture process and the excreta of the fish;Cu,Zn,Cr,Pb and As may come from the Xunsi River,agricultural fertilizer loss and pesticide residues;Cd may come from nature in addition to human actions.?8?There are no residual environmental capacities for COD_Cr,NH₃-N,TN and TP in Tangxun Lake.In order to control the total amount into lake within the allowable range,the reducing rate of each index will reach 40%,32%,47%and 32%at least in 2020,respectively.