Urbanization increases microplastic pollution in beach sediments along the Chennai Coast, South India

This study investigates the abundance, distribution, characteristics, and ecological risks of microplastics (MPs) in beach sediments along the Chennai Coast, India. Beach sediment samples from 15 sites were processed to extract and quantify MPs using a stereomicroscope, while polymer composition was identified through Raman spectroscopy. Nylon (91.2 %) was the dominant polymer, followed by polystyrene (4.4 %), polyethylene (3.98 %), and polypropylene (0.6 %). Most particles were < 1000 μm (74.8 %), indicating strong fragmentation and persistence. The mean abundance was 30.13 ± 3.13 MPs/kg, markedly lower than levels reported for highly polluted global beaches. The Microplastics Pollution Index (MPPI) categorized the Chennai coast as low in abundance (2-5), while the Coefficient of Microplastic Impact (CMPI) suggested notable ecological effects from fiber-shaped MPs. Risk indices including the Polymer Hazard Index (PHI), Pollution Load Index (PLI), and Potential Ecological Risk Index (PERI) revealed contrasting results low to minor risk by PLI but high to hazardous risk (categories IV-V) by PHI and PERI, primarily due to nylon dominance. SEM images revealed surface degradation, fractures, and adherence of particles, indicating aging and possible long-distance transport. Although overall abundance was relatively low, the predominance of hazardous polymers highlights growing ecological concern. Strengthening solid waste management, encouraging biodegradable alternatives, and recycling fishing gear are vital measures to mitigate microplastic pollution along the Chennai coast.