Prevalence of Microplastics in Coastal Area of Samae San, Thailand and Its Possible Source

Abstract

This research explored the abundance, morphology, and polymer composition of microplastics (MPs) in various environmental samples within the Samae San subdistrict involving surface soil nearby the dumping site, road dust soil, beach sand and sediment in the area with distinct land- based activities. Dumping site soil exhibited the highest concentration in items per kg of dry weight at 93,734.3, followed by road dust soil (573.0 ± 583.7), beach sand (99.8 ± 75.3), and sediment (83.1 ± 50.4). Morphological traits revealed similarities between transparent fiber-shaped particles in beach sands and sediment, and those in nearby road dust soil, while green sheet-shaped particles dominated in dumping site soil. Predominant polymer types included PE, PET, and PP, associated with daily plastics, fishing gear, and fishing nets. In beach sand and sediment samples, transparent polyamide (nylon) fibers shaped like microplastics (MPs) were notably observed, as it is a common material used in fishing nets. Cluster analysis indicated a resemblance between MPs in beach sand, sediment, and nearby road dust soil, implying that plastic debris, comprising single-use plastics and fishing equipment, could be a potential source of MPs in coastal areas.