Characteristics and distribution of microplastics in the estuarine environment and beach sands of Can Gio, Ho Chi Minh City, Vietnam

Abstract This study aims to evaluate the presence and spatiotemporal distribution of microplastics (MPs) in estuaries and beaches within the Can Gio Biosphere Reserve, Ho Chi Minh City, Vietnam, an area identified as being at high risk of MP accumulation due to anthropogenic activities and the influence of coastal dynamics. During the 2023-2024 period, over 300 water and sandy sediment samples were collected from estuaries and beaches during both the dry and rainy seasons. These samples were analyzed for MP characteristics, including size, morphology, and polymer composition, using Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) techniques. The applied sample treatment method showed an average MP recovery rate of 88%, confirming its reliability. MP concentrations were consistently higher in the rainy season than in the dry season across all matrices. The mean values for the rainy season for 2023 and 2024 were 239.22 ± 92.03 and 159.20 ± 24.72 MPs/m 3 in water, 65.86 ± 17.76 and 101.66 ± 29.86 MPs/kg dry weight in sediments, and 13.45 ± 4.06 and 18.19 ± 6.39 MPs/kg dry weight in beach sand, respectively. Particles measuring 0.3–1 mm accounted for roughly 50% of surface-water MPs and 60% of sediment MPs, whereas beach sand contained about 45% in the 2–5 mm range and 37% in the 0.3–1 mm range. Polymer analysis identified polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) as the predominant types.