| Microplastics have been widely distributed in all corners of the world,and have had a certain impact on human life,whose harmfulness to the ecological environment cannot be ignored.The distribution of microplastics is closely related to human activities.As one of the densely populated areas,the bay is an important gathering place for coastal and marine pollution.The study of microplastics pollution in the bay is an important supplement to the study of the characteristics of microplastics pollution in coastal areas.In this study,the Haizhou Bay,with multi-functional partitions,was selected as the research area.The surface water,sub-surface water,water column and seabed sediments in Haizhou Bay were sampled and analyzed in autumn in 2018 and2019,respectively.The characteristics of abundance,morphological composition and spatial distribution of microplastics were analyzed,and the flotation methods to microplastics in sediments were compared and optimized between the two voyages.Thefollowing main research results were obtained:?1?The abundance of microplastics in surface water,sub-surface water,water column and sediment in the water column area is?4.26±4.49?n?m-3,?2.6±1.40?n?m-3,?15.20±27.18?n?m-3and?0.81±0.51?n?g-1;and that in surface water in coastal areas is?40.19±24.82?n?m-3,and that in sediment is?1.51±1.16?n?g-1.?2?In vertical water of Haizhou Bay,the distribution of microplastics is"water column>surface water>sub-surface water".Most of the microplastics are concentrated in the lower and middle water column.In the horizontal water of bay,the distribution of microplastics appear to be gradually decreased from inside to outside;the microplastics in the sediments generally show a decreasing trend from the shore to the bay,but the microplastics in the sediments in the bay appear a"abundance hollow"structure,which may be caused by the rivers entering the sea and the tidal currents outside the bay.The flow disrupts the settlement of the microplastics.?3?The main characters of microplastic pollution in Haizhou Bay area are fiber,blue,and mainly small particles?<1mm?.PE and PP are the main components in water,originating from estuaries and fishing port areas.Rayon fibers and PETs are the main components in sediments,mostly from breeding areas,ports and the atmosphere.?4?In the recovery test,using Na Cl+Mn SO4saturated mixed solution through the combination of direct flotation and centrifugal flotation,the recovery rate of each component microplastics reached more than 80%,and its comprehensive recovery rate reached 83.33%?100%,and has the advantages of small sediment interference and high flotation efficiency.?5?The diffusion of microplastics in the Haizhou Bay are atmospheric transmission,Land runoff,and the source of pollution.First,diffusion through the atmosphere mainly affects the distribution of microplastics in the surface water of terrestrial ponds,tidal flats and the entire bay.Second,land runoff propagation,combined with the role of swirling currents in the bay,mainly affects the distribution of microplastics in water bodies and sediments in the bay.And the source of pollution,Haizhou Bay pollution sources are mainly distributed along the coast of the bay and the bay mouth,affecting the distribution of microplastics in all environments outside the bay.There are four main factors affecting the diffusion,the hydrodynamic forces in the bay?estuary inflow,ocean tidal current and upwelling?,filtration interception of laver culture,wind direction,dam road and port breakwaters blocking the current.In addition to the five main conclusions mentioned above,some other small conclusions were also obtained during the research.For example,the distribution of microplastics in surface water is significantly related to the migration of suspended matter.The accumulation rate of microplastics in tidal flat by runoff from land river is higher than that of water body outside the bay.The tidal flat garbage in Haizhou Bay is consistent with the spatial distribution of coastal water bodies and sediments. |
PDF Full Text Request