Occurren Cecharacteristics Of Micrplastics In The Sediments Of Typical Wetlands Of Poyang Lake

Micrplastic?which is a general term for plastic polymers with particle size less than 5 mm.?has been confirmed as an emerging pollutant,and this issue has received increased attention.Because of its small particle size and low density,microplastics in the environment can migrate under the action of external forces such as wind,river and ocean current,and can be used as carriers of organic pollutants and heavy metals,and it is easy to be eaten by animals by mistake,and the microplastics that are eaten by mistake are difficult to be excluded from the body,which will cause physical damage to organisms,blockage of the digestive tract,or cause pseudo-satiety,which will lead to the decrease of the feeding efficiency,energy shortage,injury or death of organisms.Over the past 10 years,more and more studies had demonstrated the types,abundance,distribution,sources and biological effects of microplastics in water surface and sediments in marine and coastal environments.In this study,we select the typical wetland areas in the Poyang Lake as research areas,which mainly include the areas seriously affected by human production and life activities,the entrance of the Five River Basins of Poyang Lake,the National Nature Reserves and the outflow area of the Poyang Lake Estuary and Yangtze River Section and other important wetland areas.We collected the wetland soils or sediments samples as the research materials,We used the flotation separation methods and microscopic identification methods in order to investigate the types,particle size,abundance,distribution,influencing factors and main sources of microplastics in sediments of the typical wetlands in Poyang Lake,in order to further supplement the basic data of the research on microplastics pollution in freshwater wetlands such as rivers and lakes in China,and to provide a basis for further research on microplastics pollution and its ecological impact.The main results are as follows.The results showed that foamed?polystyrene?,fiber?low density polyethylene?,and debris are found in the sediments of the typical wetlands,such as such as Poyang Lake and Le'an River section,the entrance of the Five River Basins of Poyang Lake,the outflow area of the Poyang Lake Estuary and Yangtze River Section and other important wetland areas.And the debris-based microplastics were the most important and accounted for 50%-70%of the total,followed by the film-based microplastics and fiber-based microplastics,and foamed microplastics accounted for the lowest proportion.According to the analysis results of the particle size of microplastics,microplastics with particle size less than 1 mm occupied the dominant position,accounting for more than 60%of the total number.The abundance of microplastics was calculated by the dry weight of sediments.The average abundance of microplastics in the sediments of Poyang Lake wetland was 1146.17 n·kg^-1.And the abundance of microplastics in different regions shows spatial differences.The average abundance of microplastics in the Poyang Lake and Le'an River section was 1799.56 n·kg^-1;and the average abundance of microplastics in the entrance of the Five River Basins of Poyang Lake was 1225.25 n·kg^-1;the average abundance of microplastics in the National Nature Reserves was 82.33n·kg^-1;and the average abundance of microplastics in the outflow area of the Poyang Lake Estuary and Yangtze River Section was 907.4 n·kg^-1.There were differences in the proportion,size and abundance of microplastic particles in different study areas,but all of the samples were dominated by microplastics less than 1 mm.The surface morphology and attached materials of the microplastics separated in sediments of Poyang Lake Basin were analyzed by scanning electron microscopy and energy dispersive spectroscopy.The results show that the surface of the microplastic samples in the environment is rough and the degree of weathering is obvious and there are some residuals.There are impurities such as clay in the surface crack,or attached Si,Fe,Mg,O,Al,Ca and other elements.Therefore,the surface morphology and complexity of micro-plastics that have existed in the environment for a long time will become carriers of persistent organic pollutants and toxic and harmful substances,and form diffusion pollution through co-migration in the environment.In the future,more attention should be paid to the dynamic processes and ecological effects of microplastics in the riparian environment.The distribution of microplastics in the sediments of the typical wetlands in the Poyang Lake is closely related to human activities and life activities,showing a positive correlation;the differences of microplastics abundance among different regions is influenced by human activities,hydrological conditions and river inputing,etc.The composition of microplastics among different regions is closely related to the lifestyle of people in the region and the physical and chemical properties of microplastics.