Distribution pattern and risk assessment of microplastics contamination in different agricultural systems

Contamination of microplastics in soil and water environments has become a matter of concern globally. To explore the existence of microplastics in agricultural soils, this study was carried out in different agricultural systems with distinct agronomic practices and farm inputs. A simple and cost-effective digestion-density separation method was adapted to digest, extract, and segregate different microplastics from soil to quantify the occurrence of microplastics. The pretreatment with Fenton reagent and saturated sodium chloride with further addition of 30% H2O2 at 60±2°C reduced the organic matter to 81%. After reducing the organic matter interference, microplastics were quantified. With microfibres as the most predominantly found microplastic shape, the mean abundance was observed as follows: treated sewage irrigated field (1650±0.00 items kg-1) > paddy field (1500±0.71 items kg-1) > integrated farming system field (1250±2.12 items kg-1) > inorganic fertilizers applied field (1025±4.60 items kg-1) > organic manures applied field (1000±0.71 items kg-1) > plastic mulched field (800±5.66 items kg-1). The per cent concentration of blue (37.71±3.10), black (29.41±1.75), and pink (23.87±1.62) were the commonly identified microplastic colors in the ascendancy while polyethylene was dominating among the microplastics sorted and confirmed through PCA. This study reveals that the possible sources are most likely that the inputs used in farmlands and the atmospheric deposition of microplastics in the studied agricultural lands. Such observations through systematic study emphasize the need to implement sustainable farming practices to protect agricultural soil quality and promote public health. This study is the first of its kind of work in Agricultural Soils in India, which offers significant insights into the present status of microplastic pollution in agricultural soils within the Coimbatore area of Tamil Nadu, India. These findings can potentially guide policy decisions aimed at reducing the environmental and health hazards linked to the contamination of microplastics at the initial stages.