Zulkisam Pramudia, Annesya Anggun Kinanti, Khibar Syiar Moehammad, Ilham Misbakudin Al Zamzami, M. Basyiruddin Hawali, Mega Asri Risqiana, Yogita Ayu Dwi Susanti, Andi Kurniawan
Microplastic pollution has emerged as a critical global concern due to its persistence, ecological risks, and potential to alter aquatic habitats. However, research on microplastic dynamics in tropical river systems remains limited, particularly studies that integrate multiple environmental compartments. This study investigates the abundance, morphology, and distribution of microplastics across three compartments—water, biofilm, and sediment—in the Brantas River (Malang, Indonesia), and explores their relationships with water quality parameters and sediment characteristics. Sampling was conducted at four stations representing upstream to downstream segments. Results revealed a distinct compartmental gradient: water exhibited the lowest microplastic concentrations (3–5 particles/L), biofilm showed intermediate densities (23–35 particles/kg), and sediment recorded the highest accumulation (59–114 particles/kg). Downstream stations exhibited the greatest sediment load (114 particles/kg), coinciding with slower current velocity (0.37– 0.45m/s ), elevated turbidity (up to 83 NTU), and heterogeneous sediment composition (76% sand, 12% gravel, 12% mud), which created depositional pockets favorable for particle retention. Biofilm thickness ranged from 0.023 to 0.035cm, with thicker biofilms upstream and a slight rebound downstream, suggesting that organic enrichment and calmer microflow conditions enhance particle trapping. Correlation analysis highlighted hydrodynamics and particle-related parameters as dominant drivers: microplastic abundance in water was strongly negatively correlated with current velocity (Spearman P= −0.95) and positively correlated with total suspended solids (P ≈ 0.80) and nitrate (P= 0.95), while chemical parameters such as pH and DO showed weaker associations. Sediment heterogeneity further amplified retention, as mud and gravel fractions provided greater surface area and structural complexity compared to uniform sandy beds. These findings underscore the interplay between flow dynamics, substrate composition, and biofilm development in governing microplastic fate in riverine ecosystems. Effective management should prioritize upstream plastic source reduction, control of suspended solids and nutrient inputs, and sediment stabilization to mitigate microplastic contamination in tropical rivers. © 2025, Egyptian Society for the Development of Fisheries and Human Health. All rights reserved.
Faculty of Fisheries and Marine Science, Universitas Brawijaya, Malang, 65145, Indonesia; Coastal and Marine Research Center, Universitas Brawijaya, Malang, 65145, Indonesia; Faculty of Agricultural Technology, Universitas Brawijaya, Malang, 65145, Indonesia; Faculty of Agriculture, Gadjah Mada University, Sleman, 55281, Indonesia
