Legacy landfill-derived microplastics in India: terrestrial matrix pathways, spatio-temporal dynamics, and environmental risks

Abstract

Microplastics (MPs) present widespread and persistent threats to terrestrial ecosystems by compromising ecosystem integrity, contaminating food webs, and posing significant risks to human health. This review systematically discusses the current knowledge on MPs resulting from legacy waste and landfills in India. Spatio-temporal dynamics and matrix-wise occurrence of MPs across landfill leachate, soils, sediments, compost, and air are presented. The literature indicates that MP migration is influenced by seasonal hydrology, atmospheric deposition, landfill leachate infiltration, and agricultural amendments, leading to their complex vertical and lateral distributions. Various studies indicate that MPs belong to diverse polymer types, predominantly polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with fibers and fragments as the most common morphologies of MPs. The widespread presence of MPs in various matrices further highlights the under-explored pathways of terrestrial contamination and potential food chain transfer. Despite policy advancements through frameworks such as the Plastic Waste Management Rules and Swachh Bharat Mission-Urban 2.0, the integration of MPs monitoring and mitigation into national waste and soil health guidelines is still evolving. There remains an opportunity to generate comprehensive long-term field data, establish specific standardized protocols, and fully incorporate MPs considerations into remediation and circular economy initiatives. This review signifies the importance of transdisciplinary research, improved technological interventions, and targeted policy actions to address MPs contamination in India's terrestrial ecosystems. The findings aim to inform decision-makers and researchers in developing robust, context-sensitive strategies to mitigate MPs pollution, safeguard environmental quality, and protect public health.