Microplastic Pollution in The Topsoil of Hot And Dried Areas, Human Exposure and Source Assessment, Aghili Plain, Iran

Abstract Although the distribution of microplastic (MPs) has been studied in different environmental compartments during the last decade, there is still a knowledge gap in their distribution and abundances in soil. This study aimed to investigate the abundance, distribution, and type of MPs in the soil of Aghili plain as a hot and dry area in southwest of Iran. In this study, composite soil samples (n=102) were collected from the residential and agricultural areas in Aghili plain, Iran. A combination of visual observations, Scanning Electron Microscopy (SEM) – Energy-dispersive X-ray spectroscopy (EDS), and Raman micro -spectroscopy was conducted to quantify and characterize MPs in soil samples. The intakes of MPs in adults and children were estimated through two exposure EPA scenarios. The total MPs loading in the studies soil was 11.93 ± 0.9 items in Kg-1 of surface soil in Aghili plain. The MPs had various morphology (fiber, pellet, fragment, and spherule shapes), colors (white-transparent, yellow-orange, red-pink, blue-green and black-grey colors), and sizes (<100 µm up to 1000 ≤ µm). Black-grey fibers in size less than 100 μm were dominant MPs in soil samples using a binocular microscope. Trace amounts of C, N, O, Na, P, Si revealed by EDS suggested the organic and inorganic contaminations on the surface of identified MPs. Intake of MPs per day/year through ingestion of polluted soil was calculated. Mean normal and acute exposure was estimated at 0.435 and 0.871 MPs per year through ingestion by children and adults, respectively.