Distribution Characteristics And The Source-sink Relationship Of Microplastics In Sishili Bay

As a new pollutant in Marine and coastal environment,microplastics(<5 mm)have been widely reported by researchers.Due to their large number and small particle size,microplastics can compound with other pollutants and pose a serious threat to the marine ecosystem.The offshore bay is particularly prominent as the main storage area of microplastic pollution.The study on the spatial and temporal distribution characteristics and the relationship between source and sink of microplastic pollution in the gulf can provide the scientific basis for the research on the distribution and migration characteristics of marine microplastic pollution and its ecological risks in China.This paper systematically investigated the characteristics of microplastic pollution in water and sediment and the relationship between source and sink of Sishili Bay.The main research results are as follows:(1)The abundance of microplastics in the river ranges from 0.21 to 9.15 N/L,which is at a moderate level.The seasonal variation of river microplastic abundance is as follows: February > May >November >August,and the overall distribution is higher in the dry period than in the flood period.The river hydrodynamics and artificial intervention areas such as artificial breakwater and coastal wharf are important factors affecting the river microplastic abundance.The microplastic abundance ranges from 0.13 ~ 8.1 N/L to 0.13 ~ 9.22 N/L in the surface waters and bottom waters of Sishili Bay,respectively.The distribution of the microplastic abundance has obvious seasonal differences.River transportation,fishery and seasonal changes of hydrodynamics are the main reasons for the difference of microplastic abundance distribution between surface water and bottom water in the nearshore station and offshore station.(2)The microplastic abundance range of microplastics in Sishili Bay tidal flat is 3.6 ~ 514 N/kg,and the average annual abundance of microplastics is 108.5 ± 122.0 N/kg.There is no significant difference between the abundance of microplastics in each season.The abundance distribution of microplastics is higher in the supratidal zone(the highest tidal line)than in the intertidal zone.The microplastic abundance range from 16 to 216 N/kg in the ocean surface sediments of Sishili Bay.The microplastic abundance has obvious spatial and seasonal variations,and the abundance variation is more intense in the areas with stronger hydrodynamics.(3)The abundance of microplastics has no significant correlation in the vertical direction.The river transport is an important source of the migration of microplastics in the horizontal direction.