Study On Purification Efficiency Of Lakeside Wetlands And Water Quality Characteristics Of Main Inflow Rivers In The North Bank Of Fuxian Lake

Lakeside zone,as an indispensable transitional region between terrestrial and aquatic ecosystems,is the bridge and link between the interaction and development of the two ecosystems.Due to the influence of human development and social progress,the natural environment of lakeside zone is frequently disturbed,which leads to the decline of lakeside wetland function and the serious phenomenon of lake bloom.With the implementation Plan of The Pilot Project of Ecological Protection and Restoration of Mountains,Waters,Forests,Fields and Lakes in Fuxian,Yunnan Province(2017-2020),The ecological restoration and improvement of lakeside wetland zone has become a core element of the ecological civilization construction of Fuxian Lake Basin,which is a key link to improve water quality and maintain the stability of river ecosystem,and also a major measure to implement the overall requirements of water ecological environment protection in key basins of China during the 14 th Five-Year Plan period.Fuxian lake water quality status is stable,is national one of the few Ⅰ class water lakes,bred the paleontological fossil and the ancient dian culture,build in yuxi "lakes" ecological environment of urban agglomeration is a focus of existence,as well as the sustainable development of regional economy in yunnan province are particularly precious security resources,its habitat protection and recovery is of great significance.The area of the north bank of Fuxian Lake is more than 40% of the total runoff area of the whole basin.Due to the numerous villages along the north Bank of Fuxian Lake,the concentration of population,the scale of farmland,the concentration of major rivers entering the lake,the acceleration of industrial structure adjustment and other reasons,the environmental problems in the north Bank of Fuxian Lake basin are most concentrated.As a result,the north lakeside wetland zone is the most sensitive area in the lake ecosystem to human activities.This study in fuxian lake basin north shore four lake wetland and seven main rivers into the lake as the study area objects,discusses the north shore of lake wetland of nitrogen and phosphorus removal efficiency of pollutants into the lake and the main river water quality change and the interaction between them,and for fuxian of shore lake wetland construction in hubei province to further improve to provide data support.The main results are as follows:1.The land use types of the lakeside zone on the north shore of Fuxian Lake are divided into five types: green space,wetland,road,building and square pavement.The field investigation results show that green space and wetland are the primary land use types in the study area.There are many kinds of plants cultivated in lakeside wetland,among which reed occupies a high proportion;2.In the Guangnanying-Shahai River wetland,the annual reduction of total nitrogen and total phosphorus were 11 t/a and 0.044 t/a,respectively.In xiaobaixiang wetland,the annual reduction of total nitrogen and total phosphorus were 4.342 t/a and 0.542 t/a,respectively.The annual reduction of total nitrogen and total phosphorus in Majihe wetland were 4.453 t/a and 0.912 t/a,respectively.The annual reduction of yaoniagou wetland was 6.494 t/a and 0.066 t/a,respectively.In 2021,the total nitrogen and phosphorus loads of the four lakeside wetlands were reduced by26.289 t/a and 1.564 t/a,respectively;3.The water quality of the seven main rivers in the northern part of Fuxian Lake is between Ⅳ and inferior V,and the water quality of the other six rivers can reach the standard of class Ⅲ.The single factor evaluation results showed that total nitrogen was the primary pollution factor in the estuary of the northern shore of Fuxian Lake,and nitrogen and phosphorus were the most important pollution elements in the study area.In addition,the nemero comprehensive pollution index of each sampling site ranged from 1.23 to 8.37,among which yaonigou sampling site was seriously polluted,and the other six inflow outlets of lakes and rivers were slightly polluted;4.By comparing and analyzing the changes of water quality of the four rivers flowing through the wetland and those not flowing through the wetland in the past three years,it was found that the pollutant content of Maliu River decreased most obviously,indicating that the construction of maliu River wetland improved the water quality of the lake,and the water quality purification effect of the rivers flowing through the lakeside wetland was more obvious.