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

Abstract

ABSTRACT To explore the existence of microplastics (MPs) in agricultural soils in the Coimbatore region of Tamil Nadu, India, this study was carried out in six agricultural sites with distinct agronomic practices and agricultural inputs. Using the density-digestion separation method, 81% of organic matter (OM) in soils was removed and MPs were quantified and characterised using a stereo microscope and ATR-FTIR. MP abundance of treated sewage irrigated field (1,650 items kg−1) > paddy field (1,500 items kg−1) > integrated farming system field (1,250 items kg−1) > inorganic fertilisers applied field (1,025 items kg−1) > organic manures applied field (1,000 items kg−1) > plastic mulched field (800 items kg−1) was assessed with more than 50% MPs at < 500 µm size, which exhibited that smaller MPs tend to transfer into soil layers and affect soil organisms through the food chain. The most prevailing MP colours were blue (37.71%), black (29.41%), and pink (23.87%) with polyethylene as a widely distributed polymer type among all MPs composition. The risk assessment revealed the highest hazard level in plastic mulched soil with category V contamination irrespective of the MPs abundance. This study emphasises the significant influence of agricultural inputs, irrigation practices, location, and atmospheric inputs of MPs in agricultural sites and provides a baseline for further research to understand the trophic transfer of MPs in agricultural ecosystems and its effects on the food chain.