The Distribution Characteristics,Source And Flux Of Microplastics From Daliao River Into The Sea

Microplastic pollution has become one of the important issues that cannot be ignored in many environmental problems.Although a series of investigations and studies have been carried out on microplastic pollution in China and abroad,it is still insufficient in comparison with the widespread pollution of microplastics.Moreover,there are few domestic studies on the pollution of microplastics in rivers,and there is a lack of specific information on the distribution of microplastics in rivers.The pollution of microplastics in the river flowing into the sea area comprehensively reflects the total amount of microplastics discharged into the ocean,which has important research significance.This study investigated the pollution of microplastics in the water of the Daliao river where entering the sea,and mainly included following aspects:(1)Two field sample collections were carried out.Surface,middle and bottom water samples of Daliao river were collected using pumping methods,and large plastics floating on the surface of Daliao river were monitored;(2)The samples were pre-processed and tested,mainly including pre-treatment experiments such as screen filtration,digestion,density separation,suction filtration and microscope observation selection,Fourier infrared instrument analysis and detection process,and blank experiments and addition experiments were conducted to estimate the background pollution rate and recovery rate of microplastics in samples;(3)Analyzed the abundance and distribution of microplastics in the water of the Daliao river sampling area,estimated the.total amount of microplastics discharged from the Daliao river to the Bohai Sea in 2019,traced the possible sources of microplastics in the water body of the Daliao river,analysis and summary of the composition,shape,particle size and other information of the microplastics in the sample are carried out.Through the detection and analysis of the water samples of the Daliao river,it was found that microplastics was detected in all samples,and the detection rate was 100%.The average abundance of microplastics in the surface water at the estuary is 0.475 n/L,with an average concentration of 0.00057 mg/L.And the average abundance of microplastics in the surface water of the TianzhuangtaiLiaohe Bridge is 0.006 n/L,with an average concentration of 0.00041 mg/L,the average abundance of microplastics in the middle water is 0.014 n/L and the average concentration is 0.000738 mg/L,the average abundance of microplastics in the bottom water is 0.008 n/L and the average concentration is 0.000031 'mg/L.It is estimated that the total amount of microplastics discharged into the Bohai Sea by the Daliao river in 2019 is 4.12 × 1010,about 280.70 kg.The observation found that there are large floating plastics in the surface water of the Daliao river.In the six observations,9 large floating plastics were founded,and there is about 720 large plastics floating into the sea in the day.In terms of color,colorless microplastics have the largest number,accounting for 57.28%of all plastics.In terms of shape,the number of fibers is the largest,accounting for 88.84%.In terms of composition,PET components have the largest number of microplastics,accounting for 74.53%.In terms of particle size,the number of microplastics is the largest in the range of 1-1.5 mm(19.77%),followed by microplastics of 1.5-2 mm(19.50%),and microplastics smaller than 2.5mm are the main components,accounting for 70.65%of all plastics.From the differences in the shape and composition of microplastics in the surface waters of the TianzhuangTaiLiaoHe Bridge and the estuary,it is speculated that the microplastics discharged from this section mainly originated from the laundry of local residents.The above research results illustrate,there is a certain amount of microplastics in the water of the Daliao river,which will be discharged into the Bohai Sea along with the river water,and further affect the ecosystem of Bohai Sea.Therefore,it is necessary to take timely actions to reduce microplastic pollution.On the one hand,residents environmental awareness should be strengthened,and the use of products containing microplastics should be reduced,on the other hand,the treatment process of the sewage treatment plant should also be improved,and the micro plastic treatment link should be added.Seriously reduce the amount of microplastics in domestic sewage and reduce the losses caused by microplastics in rivers and marine ecological environment.