Microplastic Abundance in Water and Sediments in the Opak River Estuary, Bantul, Special Region of Yogyakarta

Abstract

Microplastic pollution in estuarine environments has attracted growing attention due to the persistence, widespread distribution, and potential ecological impacts of plastic particles. This study aimed to assess the abundance and characteristics of microplastics in water and sediment at the Opak River Estuary, Bantul Regency, Special Region of Yogyakarta, Indonesia. Sampling was conducted at five stations representing different environmental gradients under ebb and flood tide conditions. Water and surface sediment samples were analyzed using particle-based approaches. Microplastics were extracted through organic matter removal, density separation, and filtration, and subsequently identified based on shape, size, and color. Microplastics were detected in all water and sediment samples. Mean microplastic abundances were 1,221.6 particles/kg in sediment and 39.8 particles/L in water. In the water samples, mean microplastic abundance was higher under the sampled flood condition (56.4 particles/L) than under the sampled ebb condition (25 particles/L); this difference describes the sampling observations and does not establish a consistent tidal pattern. Fragments were the dominant shape in both water and sediment, while black was the most frequently observed color.