A Study On Microplastics Pollution In The Vegetable Farmlands Of Suburban Wuhan And The Ecotoxicology Response Of Microplastics On Earthworms(Eisenia Fetida)

Plastic particles with a diameter of less than 5 mm are described as microplastics.Pollution caused by microplastics which are regarded as emerging contaminants has become a global problem to be solved urgently.Marked by their extensive sources,degradation-resistant,easy to migrate,and potential to be ingested by organisms,more and more attention has been paid to the presence of microplastics in the environment due to their potential risk In recent years,quite a number of research were mainly focuses on the occurrence of microplastics in aquatic environment,but there is still a lack of understanding of current situation of microplastics pollution in the soil environment.To this end,this study analyzed the existence of microplastics qualitatively and quantitatively in the soil of suburban vegetable fields,and studied the ecotoxicological effects of microplastics on soil biomarker-earthworms(eisenia fetida)by control experiments in the laboratory.Results of these studies are as follows:Microplastic concentrations ranged from 320-12560 items/kg in all of the twenty soil samples,with the average concentration 2020 items/kg.Among them,average abundance of microplastics near suburban roads is 1.8 times than that in residential areas.Most of the detected microplastics were with colors,and the largest proportion of microplastics with particle size less than 0.2 mm was 70%.The major shapes of the detected microplastics were microbeads and fibers,which accounted for 48% and 37%,respectively.The main components were polyamide and polypropylene,accounting for 32.5% and 28.8%,respectively.Earthworms were found to ingest and excrete microplastics.Microplastics with smaller size accounted for a higher proportion in earthworms' casts.After exposure of 28 days,damage phenomenons were observed at higher concentrations.Microplastics could induce the oxidative stress and stimulate the neurotoxic response to some extent.In total,low-density polyethylene microplastics could have negative effect on earthworms.According to this study,microplastics pollution was widely existed in vegetable soil,and there are variety of microplastic types.Earthworms' health may be threatened after exposure to a given concentration of microplastics over a long period of time.This study is of great significance for understanding the current situation of soil microplastic pollution and evaluating the impact of soil microplastic pollution on soil organisms,and provides scientific reference for controlling the use of agricultural plastic products and input of plastic waste as well as the treatment of microplastic pollution in soil.