Occurrence and confirmation of microplastics in cockles and mussels from aelected sites on the West Coast of Peninsular Malaysia using FTIR analysis

Abstract

The global use of plastics continues to increase annually, leading to widespread accumulation of microplastics (<5 mm) in marine ecosystems. These degraded particles often settle in sediments and may be ingested by filter-feeding organisms, enabling microplastics to enter the aquatic food web and potentially pose toxicity risks to consumers. This study aimed to determine the occurrence, physical characteristics, and polymer types of microplastics present in the tissues of two commercially important shellfish species, cockles (Anadara granosa) and mussels (Corbicula leana). Three samples each of cockles and mussels (three replicates per site) were collected from Sebatu, Melaka, and Tanjong Karang, Selangor, representing selected sites along the west coast of Peninsular Malaysia. Possible microplastics were isolated after Nitric Acid (HNO₃) digestion and observed using light and fluorescence microscopy at 40× magnification. Physical characterisation revealed several distinct morphotypes, including red subangular jagged fragments, grey irregular fragments with surface grooves, black elongated fibres with broken edges, red subangular fragments, red spheruloid-shaped pellets, and crystalline clear thin elongated filaments. These characteristics are consistent with the commonly reported forms of microplastics in bivalves worldwide. Polymer identification using Fourier Transform Infrared (FTIR) spectroscopy (4 cm⁻¹ resolution) confirmed the presence of Polypropylene (PP), Polystyrene (PS), and Polyethene (PE) as the dominant polymer types. Principal Component Analysis (PCA) demonstrated clear spatial separation between sampling sites and species, accounting for 96% of the total variance, with significant differences observed between groups (p < 0.05). Overall, this study provides important baseline data on the physical and chemical characteristics of microplastics in Malaysian shellfish and supports future efforts in environmental monitoring, seafood safety assessment, and marine pollution management.