Research On The Release,Flux And Driving Factors Of Microplastic Fiber From Textile Washing

The process of synthetic textile washing is considered to be one of the most important sources of marine microplastic pollution.Textile washing methods mainly include hand-washing and machine-washing.However,existing researches mainly focused on the release behavior of microplastic fiber in machine-washing.Traditional hand-washing is still the main textile washing method in rural areas of developing countries.Since the lack of quantitative research on the release of microplastic fiber from synthetic textiles under hand-washing,the studies can only use emission factor of machine-washing to estimate regional microplastic fiber emission.Current studies may overestimate the contribution of textile washing to environmental microplastic pollution.Therefore,we conducted a systematic study on the release behavior and mechanism of microplastic fiber under traditional hand-washing condition.By simulating household washing,we determined the microplastic fiber emission factor of hand-washing and explored the influence of various washing conditions on fiber release during the process of hand-washing.At the same time,the machine-washing experiment was conducted under the same condition to compare the differences and similarities in the microplastic release behavior of hand-washing and machine-washing.Based on the data of emission factors and emission activity level from the experiment and related studies,we developed a microplastic fiber emission flux model and estimated the flux into the ocean with the hydrological information of global rivers.Finally,we used the geographical detector method and structural equation model to explore the driving factors of the spatial distribution of microplastic fiber emission.This study has potentially important guiding significance for the prevention,control and treatment of global microplastic fiber pollution.The main conclusions are as follows:(1)This study can provide support for the method to quantify the release of microplastic fiber from polyester textiles during the process of hand-washing.Machinewashing experiments were also conducted under the same conditions.The microplastic fiber emission factors of hand-washing and machine-washing were 37.84 mg/kg and222.84 mg/kg,respectively.In addition,the effects of various factors on the release behavior of microplastic fiber during polyester textile washing were determined.It was found that temperature,type of detergent,washing time and volume of washing water had no significant influence on the release of microplastic fiber,while the use of detergent,soaking in water and use of washing board will increase the release of microplastic fiber.This study complemented the database of microplastic fiber emission factor and can reduce the uncertainty in estimating the regional microplastic fiber flux into the ocean.(2)This study developed a model to calculate the microplastic fiber emission flux with the emission factor obtained from washing experiment and the relevant data of the emission activity collected from the official database.It is estimated that the environmental microplastic fiber emission flux released from global synthetic textile washing is 0.87 million tons in 2021,one seventh of the microplastic fiber emission entered the marine environment through the river estuary.The global high resolution emission inventory of microplastic fiber was established with the spatial allocation method and visualized by Arc GIS.According to the result,the microplastic fiber emission showed obvious characteristic of spatial differentiation.The result was the base of exploring driving factors of microplastic fiber emission.(3)In this study,the geographical detector and structural equation model were used to explore the driving factors for the spatial distribution of regional microplastic fiber emission.The study showed that the spatial differentiation was the result of the combined effect of human factors and natural factors.The population and level of economic development were the decisive factors.Natural factors such as temperature and precipitation indirectly influence the spatial distribution of microplastic fiber emission through affecting human factors.The determination of driving factors is of great significance for further modeling and analysis of environmental microplastic.The study can provide a more comprehensive understanding of the differences in the release behavior of microplastic fiber between hand-washing and machine-washing.And the result can offer guidance on using green and environmental-friendly textile washing methods for public.In addition,we assessed the contribution of textile washing to environmental microplastic pollution with the microplastic fiber emission flux model.The determination of spatial driving factors is important for understanding the cause of microplastic fiber pollution.This study can provide support for policymakers in formulating specific environmental measures.