Study On The Occurrence Characteristics And Flux Changes Of Microplastics In The Main Rivers Leading To The Sea Around The Laizhou Bay

Microplastic pollution has become an environmental problem that cannot be ignored in the world.Although some investigations and studies have been done on microplastic pollution at home and abroad,compared with the research progress of microplastic pollution in large-scale water bodies,it is important for small-scale rivers.Further research on the distribution and migration process of microplastics in water bodies is still insufficient,and domestic research mainly focuses on marine microplastics pollution.There is less research on the pollution of microplastics in rivers,and there is a lack of microplastics distribution in different rivers.Due to the greater impact of human activities,the problem of microplastics pollution in coastal areas is the most serious.In this process,the transport of rivers into the sea is particularly important.Therefore,we investigate the characteristics and abundance of microplastics.It is the key to solve the problem of marine microplastic pollution,and it is even of great significance to explore the interaction between land and sea.The main rivers flowing into the sea around Laizhou Bay include the Yellow River,Xiaoqing River,Wei River,etc.Our research group has carried out research on the microplastic pollution in the lower reaches of the Yellow River,and achieved certain results.As another important river flowing into the sea around Laizhou Bay,the Xiaoqing River is another important sea-flowing river around Laizhou Bay.It passes through five cities above the prefecture level of Jinan,Binzhou,Zibo,Dongying and Weifang,and receives a large amount of wastewater discharged from production and domestic sewage treatment plants along the way.It is the main land-based pollution source of microplastics around Laizhou Bay,thus becoming a typical microplastic pollution to study the occurrence of microplastics in the Xiaoqing River,this paper analyzes the occurrence characteristics of microplastics in the surface water of three sections of the Xiaoqing River upstream of the Jinan Licheng section,the downstream Dongying Shicun section and the Weifang Yangkou section of the estuary.Temporal distribution changes were investigated:in terms of spatial distribution,the presence of microplastics was found at all sampling points.The pollution degree of microplastics in the surface water of Jinan was the highest,and the annual average abundance was1691 n/L,followed by the Dongying section,with an annual average abundance of microplastics of 864 n/L,while the Weifang section has the lowest average annual abundance of microplastics at 432 n/L;in terms of time distribution,the total microplastics in the wet period The abundance is the highest at 4712 n/L,followed by the normal water period.The total abundance of microplastics is 2655 n/L,and the total abundance of microplastics is the lowest at 1596 n/L in the dry period.In terms of morphology,fiber type and the main form of microplastics is mainly small,and the distribution of the main forms of microplastics is affected by seasonal changes.The type that accounts for the highest proportion in the Xiaoqing River during normal and dry periods is fiber,which is 48.47%and 83.34%,respectively.In the wet period,the main type of microplastics of Xiaoqing River is pellets,accounting for as high as80.28%,followed by fragments and films.Particles and flocs are relatively rare.In terms of comparison of the three sampling points,the sampling point in Jinan Licheng is mainly small spherical microplastics,the sampling point in Dongying Shicun is mainly film-type microplastics,and the sampling point in Weifang Yangkou is mainly fiber-type microplastics.Seasonal changes will also affect the particle size distribution of microplastics.Generally,the abundance of microplastics in the range of 50-100μm is the highest,and the depth and particle size are inversely proportional to the vertical direction of the water body;by scanning electron microscopy And infrared spectrometer analysis to determine that the main microplastic components in the sample are polyethylene,polypropylene and polystyrene;the difference in the shape and composition of the microplastics in the three sections has been carried out to analyze the sources and influencing factors of the microplastics in the water body,and it is speculated that point or non-point source plastic waste pollution from human activities,river hydrological conditions,and the density of microplastics themselves are the main reasons for the spatial differences in the distribution of microplastics in water bodies;according to the abundance data of microplastics in the Xiaoqing River during normal,dry and wet periods,the period from 2019 to 2020 is estimated The annual flux of Xiaoqing River microplastics into the sea is 3.3×10¹³,and the mass is about 1099 tons,and compared with the abundance of microplastics and flux into the sea in the lower Yellow River.In addition,after a lot of research,this study also systematically summarizes and compares the extraction of river microplastics and the estimation of the flux into the sea at different spatial scales at this stage.Methods and main research results,while pointing out unsolved problems and making suggestions and prospects for future research content;research shows that compared with global models,the model prediction results obtained at a specific regional scale are more accurate,and most models only For qualitative research,there are fewer models for quantitative analysis,and it is urgent to develop and improve the calculation method of the flux of microplastics into the sea;because the abundance of microplastics is affected by changes in the temporal and spatial scales,the monitoring and extraction process of microplastics is particularly important.However,The lack of quantitative data on land-sourced microplastics is one of the biggest limiting factors in the study of microplastics pollution.Therefore,the establishment of a standardized river microplastics monitoring system to quickly and efficiently extract microplastics and obtain accurate microplastics data is the application of this research field.Issues of focus.