Spatial Distribution Characteristics And Influencing Factors Of Microplastics In Surface Water Of Dianchi Lake

In recent years,water microplastic pollution as an ecological and environmental problem has paid much attention,and the previous research on water microplastics mainly focused on the marine environment.The water body of plateau lakes is not only an important part of human being production and life but also an important carrier of environmental changes.The relevant researches on microplastics pollution in lakes are very few.The research direction of microplastics in lake mainly includes their physical and chemical properties,source analysis and harm,while there are few studies focusing on the influencing factors of the microplastics’spatial distribution.Therefore,this paper takes Dianchi Lake as the research area,discusses the occurrence characteristics of microplastics in the surface water of Dianchi Lake,further analyzes the correlation among the distribution of microplastics and surrounding pollution sources,underwater topography,and finally analyzes the potential ecological risks of microplastics in Dianchi Lake by using different ecological risk assessment methods.The main research of this paper are as follows:(1)The average abundance of microplastics in the surface water of Dianchi Lake was 2902 n/m~3,and the overall distribution is more south than north,and the lake is at a median pollution level.The shape of micro-plastics is mainly fiber,accounting for 94.4%;the colors are mainly transparent and blue,accounting for 50.3%and 31.6%respectively;the particle size is mainly<1 mm,accounting for 53.6%;Polyethylene is the main chemical component,accounting for 36.2%.(2)The spatial distribution of microplastics in Dianchi Lake is only related to the distance off fishing villages.In the northern lake region,the abundance of microplastics is positively correlated with the distance of sewage treatment plants,tourist attractions,banks and estuary.In the southern lake region,there was no correlation between the abundance of micro-plastics and the distance of pollution sources.(3)The abundance of microplastics in Dianchi Lake is only negatively correlated with the roughness.The abundance of microplastics in the northern region is negatively correlated with the curvature,slope and relief of the topographic factors,and positively correlated with the water depth.The abundance of microplastics in the southern region is negatively correlated with roughness only.(4)Hydrodynamic conditions also affect the spatial distribution of microplastics in Dianchi Lake surface water.Under the action of lake current,the northern water flow speed is"fast along the coast and slow in the center of the lake",and the coastal water flow migrates and converges to the lake center area after accepting the surrounding microplastics,so that the lake center points that are far from the northern pollution source are highly abundant.The southern lake flow is weak and the south has only outlet,and microplastics are mainly imported by the northern lacustrine flow and surrounding pollution sources.Therefore,the abundance of microplastics in the southern region is high and the distribution is relatively uniform,and there is no spatial correlation with the southern pollution sources.(5)The risk index of microplastic polymers shows that the risk level of microplastic pollution wasⅣ,belonging to serious pollution degree.The pollution load index indicates that microplastic pollution is at a low risk level.The ecological risk index method shows that Dianchi Lake is affected by multiple types of polymers,among which PVC and PU polymers are the key factors affecting the ecological risk of Dianchi Lake.This study shows that there are a certain amount of microplastics in the surface water of Dianchi Lake,and their spatial distribution is affected by many factors,which provides a new idea for the prevention and control of microplastics in the water of Dianchi Lake.