Assessment of Microplastic Contamination in Surface Waters and Sediments of Pool Malebo, Congo River, Democratic Republic of the Congo

Abstract

Data on microplastics in Central African inland waters remain limited. This study assesses contamination in the surface waters and surficial sediments of four Pool Malebo sites: Maluku, Kinkole, Kingabwa-Baramoto, and Kinsuka, Democratic Republic of the Congo. Sampling was conducted in June 2024, with three independent replicates per site. Water samples were vacuum-filtered, and sediments underwent KOH digestion followed by vacuum filtration. Suspected particles were characterized by stereomicroscopy, and selected particles were identified by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). Mean abundance ranged from 85 to 196 particles L⁻¹ in water and from 410 to 720 particles kg⁻¹ of dry sediment. Kingabwa-Baramoto showed the highest mean abundances, with significant differences among sites in both compartments (p < 0.001). Fragments and films were dominant. The main polymers identified were polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). These findings provide baseline data for Pool Malebo and highlight the need for harmonized, repeated monitoring of microplastic pollution in the Congo River system.