Spatial Distribution Of Nitrogen And Phosphorus In Water,Sediments And Environmental Risk Analysis Of Janhu Lake

Lakes are an important part of terrestrial ecosystems and an effective collection of information for lake basins.With the development of social economy and human activities intensifying the behavior of lake disturbance activities,a large number of lake problems have also arisen,such as the degradation of lake ecosystems,the serious eutrophication of lake water bodies,the shrinkage of lakes and the flooding of lakes.The reduction of storage capacity,etc.,the existence of these problems seriously restricts the sustainable development of the ecological economy within the basin.Surface sediments are effective carriers for lakes to record lake information.The study of lake surface sediments can not only effectively understand the hydrological characteristics and sedimentary environment of lakes and watersheds,but also effectively reflect the current ecological environment of lakes and lakes.Nutritional status and level of pollution.Jianhu Lake is a small shallow lake in the Yunnan-Guizhou Plateau.It is a key area for biodiversity conservation in northwestern Yunnan and plays an important role in the maintenance of regional ecological environment functions and biodiversity.In recent years,with the rapid development of the surrounding areas and the intensification of pollution,the Jianhu Basin is facing serious forms of environmental pollution.The continuous human disturbance activity caused the nutrient content in the water body of Jianhu Lake to increase continuously,and the water body eutrophication appeared in different degrees,which caused the ecological environment function of the basin to gradually decrease,the lake swamping trend increased,and the lake area gradually narrowed,which is a serious threat.The function of the lake is played.Therefore,this paper collected 50 surface samples from Jianhu Lake in Yunnan Province,using the total nitrogen?TN?,total phosphorus?TP?,organic carbon,nitrogen and its stable isotopes in the surface sediments of Jianhu Lake and the water quality parameters of the water body.The surface sediment particle size and other indicators were used to analyze the spatial distribution characteristics of TN and TP in the water and surface sediments of Jianhu Lake and the sources of organic matter,and the following main conclusions were drawn:?1?The experimental results show that the total nitrogen?TN?content in the surface sediments of Jianhu Lake ranges from 2148mg/kg to 9550 mg/kg,the average content is 4609 mg/kg,and the maximum variation is 7402 mg/kg.The TP)content ranges from 757 mg/kg to 1744 mg/kg,the average content is 1223 mg/kg,and the maximum amplitude is 986 mg/kg.The total organic carbon?TOC?content ranged from 1.05%to 5.46%,the average content was 2.15%,and the maximum variation was 4.41%.The organic matter?OM?content ranged from 4.25%to 21.3%,and the average content was 11.57%.It is 17.05%;the carbonate content is between4.06%and 19.25%,the average content is 10.14%,and the maximum variation is15.19%.The surface sediments TN,TP,TOC,OM and carbonate have similar distribution characteristics in space,showing high values in the East and West Lake areas and low content in the Central Lake area.?2?The total nitrogen content?TN?of Jianhu Lake is between 0.34mg/L and2.08mg/L,the average content is 0.64mg/L,the maximum amplitude is 1.74mg/L;the total phosphorus content?TP?of water is between 0.06mg/L⁰.34mg/L,the average content of 0.08mg/L,the maximum amplitude of 0.28mg/L.The spatial distribution characteristics are characterized by western>central>eastern,and the whole water quality is poor,especially in the western lake area.The TN and TP are1.30 and 1.32 times of the whole lake,It directly illustrates that Yongfeng River is the main input river of exogenous TN and TP in Jianhu Lake.?3?The organic carbon isotope(?¹³C)value of Jianhu Lake is between-30.08‰and-24.86‰,with an average of-28.28‰and a maximum amplitude of 5.23‰.The nitrogen isotope(?¹⁵N)value ranged from 2.45‰to 5‰with an average of 3.84‰and a maximum amplitude of 2.56‰.The carbon-nitrogen ratio?C/N?of surface sediments in Jianhu Lake ranged from 10.76 to 16.53,with an average of 12.59.The variation range was large,and the maximum variation was 5.77.The surface sediments in different lake areas have different C/N ratios.From the perspective of spatial distribution,they are similar to the TN and TP distribution characteristics of water bodies and sediments,and both show the highest average content in the western lake area,reflecting the external input of rivers.Lake water bodies and sediments have a greater impact.