اAssessment of soils pollution in suburb of Gorgan city to heavy metals and microplastics

The present study aims to evaluate the concentration, level of pollution, source, and health risk induced by heavy metals and microplastic particles in the agricultural soils of the Gorgan city suburb. For this purpose, 21 topsoil samples (0-30 cm) were collected. Soil’s physicochemical parameters, concentration of heavy metals, and the quantity and general characteristic of microplastic particles (were investigated using standard methods. The obtained results show that the texture of the samples is clay-sand loam and sandy loam. pH of the samples is slightly alkaline to moderately alkaline, the average contents of carbonate and organic matter are 19.8 % and 1.2 %, respectively, and the average cation exchange capacity of the samples is 18.7 meq/100g. While the average concentration of Cu, Zn, Cr, Mn, Co, Fe, Ni, and Sb are higher than the world soil average composition, the average contents of As, Pb, and Cd are comparable or lower than the standard values. Human health risk assessment shows that among the studied elements, Cr has the highest carcinogenic and non-carcinogenic risks through ingestion, inhalation, and dermal contact routes, for both children and adults. Microplastics are present in all soil samples in the form of fibrous, pellet, fragmental and spherical, and and most particles are bigger than 1000 μm. FT-IR analysis indicates that micrometers are polymers that are mainly composed of polyethylene, pointing to the agricultural source of microplastics particles. The results of this study show that agricultural activity is the most important source of soil pollution in the suburbs of Gorgan city and can induce health risks to the residents of the study area.