Spatial distribution and ecological risks of microplastics in agricultural soils near a solid waste dumpsite in southwest Bangladesh

Microplastics (MPs) accumulation can potentially influence soil fertility and plant productivity. MP pollution and spatial distribution in terrestrial environments, particularly in agricultural soils surrounding the municipal solid waste (MSW) dumping site in southwest Bangladesh, is still not investigated. The objective of this study was to quantify, characterize, and assess the ecological risks of MPs in agricultural soils surrounding the MSW dumpsite of Khulna City Corporation (KCC) in southwest Bangladesh. Ten (10) composite agricultural soil samples surrounding the MSW dumping site were collected and processed for MPs and trace metals analysis. We investigated the abundance, spatial distribution, characteristics, polymer types, and ecological risk of observed MPs. The results exhibited that the mean abundance of MPs was 5567 items kg (range from 1667 to 11,000 items kg), and the dominant shape, size, and color were found in fibers (~ 43%), < 1 mm, and blue, respectively. Polyvinyl chloride (PVC) was the dominant polymer followed by HDPE and nylon among the 14 identified polymer types across the study site's soils. Spatial analysis showed that the old dumpsite, along with agricultural soils in the vicinity of the active dumpsite, was polluted with the MPs and heavy metals. The investigated sites were classified as risk category I due to MP pollution, and the findings indicate a decrease in MP abundance as the distance from the dumping site increases. Principal component and correlation analysis indicate different anthropogenic sources of MPs and heavy metals pollution, namely the solid waste dumpsite and improper agricultural activities (p < 0.05). The findings highlight the need for integrated management strategies to prevent microplastic pollution in agricultural soils to ensure soil health and crop productivity.