Diversity analysis and risk assessment of microplastics in terrestrial soil across different landuses of northern India

Abstract

Microplastics (MPs) are widely acknowledged as emerging pollutants in terrestrial ecosystem, yet their ecological threats in soil remain uncovered. This study presents the first comprehensive assessment of the abundance, characteristics, diversity, and ecological risks of soil-borne MPs across eight distinct landuse types in India, including industrial areas, dumping sites, municipal areas, wetlands, and various agricultural settings. Soil samples were collected and analyzed for MP abundance (MPs kg−1), morphology, polymer composition, diversity assessment and potential environmental risks. The results revealed the highest mean MP abundance in industrial areas (3710 ± 1127), followed by dumping sites (3310 ± 2195), municipal city areas (1247 ± 386), agriculture near dumping sites (546 ± 204), urban agriculture (478 ± 94), agriculture with plastic mulching (210 ± 54), peri-urban agriculture (113 ± 34), and wetlands (63 ± 21). Predominant shapes were fragments, fibers, films, and the particle sizes majorly belonged to 10–300 µm and 300–500 µm. Low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP) were the most abundant polymers in all the landuses. Shannon-Wiener index (SWI) and Simpson Diversity index (SDI) indicated significant variations in MPs diversity across landuses for shape, size, color, and polymer composition. Landuses were categorized as Level V (>1000) in terms of the Polymer Hazard Index (PHI), while Pollution Load Index (PLI) suggested a minor risk level. Based on the Potential Ecological Risk Index (PERI), wetlands exhibited low-risk and rest other landuses represented low to very high-risk category. The Geo-accumulation Index (I<inf>geo</inf>) was also computed and evident as less contaminated landuse (wetland) to extremely contaminated (industrial area) landuse. This study provides baseline data on the occurrence and ecological risk of MPs in Indian soil and highlights the urgent need for targeted mitigation strategies. The findings contribute to a better understanding of MP dynamics across landuses and emphasize the necessity for policy interventions in terrestrial MPs management. © 2025 International Association for Gondwana Research