| As one of the most widely used materials,plastics play an important role in human development and daily life.But while microplastics bring great convenience to human beings,they also bring all kinds of adverse effects.Microplastics have a small size,strong persistence,and easy to enrich,easy to absorb pollutants in the environment and other characteristics will cause all kinds of risks to the environment.In this paper,the study of the song hua river water system,the song hua river through Harbin city,has become the city inseparable organism,the song hua river,also as all kinds of waste water discharge water,including production and industrial and agricultural water discharge,etc.,and as the mother river of Harbin,flow through the city,is closely related to human life,so on the song hua river in micro plastic occurrence characteristics,migration and the source of self-evident,can not only provide ideas for water treatment,and fill the gaps in this area in northeast China.In this study,samples were collected at various medium points along the Songhua River.The sample section selected the main urban section of Harbin,to identify,quantify and characterize microplastics(microplastics,MPs)to investigate the distribution and migration within the water samples and between the sediments,and to analyze the pollution sources.The following results were obtained:Microplastics were detected by collecting water samples and sediment samples from all points in the Songhua River system.The abundance of microplastics in the dry season was 190N/L-500N/L.The proportion of morphology was fiber microplastics>debris microplastics>thin film microplastics>granular microplastics.In the study area,five types of microplastics were found,namely polyethylene(PE),polypropylene(PP)and polystyrene(PS)polyethylene terephthalate(PET)and polyamide(PA).Most transparent color is less color.The smaller the particle size,the larger the proportion,and the proportion of millimeter-level microplastics is the smallest.In the wet period,the abundance of microplastics in the samples was 160N/L-420N/L.In the overall analysis,the proportion of debris and fiber was close and high,but the proportion of film increased to 30%,and the lowest proportion of granular was 7%.The proportion of fiber>debris>film>particles.Most transparent color is less color.The particle size of microplastic shows that the number of particles increases with the particle size.Detailed understanding of the microplastics in the Songhua River water occurrence characteristics and pollution situation.Through the collection and analysis of the sediment of Song hua River,microplastics were found in all points of the sediment of Songhua River during the dry season,with the abundance range of 950N/kg～3050N/kg.The shape of microplastics in the sediment is divided into four types:particles,film,debris,and fiber.The fiber is the main shape PE proportion of all the samples is still the largest,occupying the second place is PP,followed by PS and PA,and finally PET.Color black accounts for the majority.The particle size of microplastic shows that the number of particles increases with the particle size.Microplastics were found in all points in the sediments of the Songhua River system during the wet season,with the abundance range ranging from 900N/kg to 2889 N/kg.However,the proportion of types in the sediments was slightly different,and the proportion of PET significantly increased the microplastics in the sediments,the third was PP,followed by PS and PA,and black was in the majority.The particle size of microplastics shows that the number of particles increases with the decrease of the particle size.In addition,through the analysis of the occurrence characteristics of water and sediments in the Songhua River system,it can be concluded that high-density,fragmented and large particle size microplastics are easy to produce the vertical migration of deposition,while in contrast,light fibers with small particle size and thin-film microplastics are prone to lateral migration.In general,the content of microplastics in the sediment is much higher than that in the water samples,proving that the sediment is the"sink"of microplastics.When rainfall,agricultural runoff,urban inland rivers,snowmelt runoff,and stormwater runoff are formed.Based on this,the Arc GIS hydrological analysis module was used to analyze and calculate the hydrological characteristics of the river such as the missing river rainfall catchment area,and the runoff of the inflow runoff at different times was obtained:the runoff of rainwater during the flood period,urban inland river,and agricultural field runoff were 9.2×10~6,1×10~6,7.1×10~5m3,respectively.The runoff of stormwater runoff,urban inland rivers,agricultural runoff,and snowmelt runoff during dry periods is 3×10~7,1.35×10~5,9.2×10~4,1.09×10~5m3.The runoff of stormwater runoff,urban inland rivers and agricultural land runoff during the flat water period was 2.32×10~6,2.6×10~5,1.8×10~5,respectively.The average abundance of different scenario media was obtained to calculate the inflow flux:the inflow of microplastics in the flood period was 3.14×10~9,the inflow in the dry period was 3×10~8,and the inflow in the flat water period was 7.9×10~8.Through the field investigation of the environmental media around the Songhua River system,and the multi-environmental samples were processed to obtain the microplastic occurrence of tributary wastewater outlet,farmland,atmosphere and surrounding snowmelt runoff,and the three-layer neural network analysis method was used to explore the source of microplastics in the Songhua River system.Using the classification learner of machine learning and deep learning in MATLAB,the source classification and prediction accuracy of the data was 96%,and the prediction accuracy of the flood period was 96%,and the prediction accuracy of the dry period was 94%,and the prediction accuracy of the two periods was high,and the model prediction was accurate.Based on the above research,the temporal distribution of the microplastic occurrence characteristics of the river in the Harbin section of the Songhua River in the flood period and the dry period was analyzed,and the sediments along the flood and dry periods were collected to study the microplastic occurrence of the sediment of the Songhua River,and the spatial distribution law was obtained,and the migration analysis was carried out by combining the two.The occurrence of microplastics in multi-environmental media in the Songhua River Basin was carried out,the characteristics of the surrounding environment were understood,and the suspicious sources of microplastics were analyzed,which provided a basis for the protection of the management of the Songhua River Basin.This work provides information about MPS pollution for future studies of freshwater systems and provides new insights into the source allocation of MPs. |
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