Seasonal Variation in Microplastic Abundance and Distribution in Sediments of the Andoni River Estuary, Nigeria

Microplastic pollution is increasingly a significant environmental hazard, particularly within aquatic ecosystems. Despite increasing global concern, there is a notable lack of research on the seasonal variability of microplastics in the estuarine environments of the Niger Delta, an area recognized for its ecological richness and economic importance. This study filled the research void by examining the abundance, distribution, and polymeric composition of microplastics during both the wet and dry seasons across six sites within the Andoni River system. The primary objective was to evaluate spatial and temporal variations in microplastic contamination and assess the pollution intensity of concentration factors and the Pollution Load Index (PLI). Samples were systematically collected from surface water at each site throughout both seasons, followed by meticulous laboratory analyses utilizing microscopic and spectroscopic methodologies. The findings indicated a higher abundance of microplastics during the wet season (10,942 particles/kg) compared to the dry season (7,488 particles/kg), with Site 6 consistently exhibiting the highest concentrations. Fibers and fragments emerged as the predominant morphologies, while polyethylene, polypropylene, and polyethylene terephthalate were identified as the most prevalent polymers. The PLI assessments signified moderate to high pollution levels, particularly at sites affected by anthropogenic activities such as illegal bunkering and fishing. These results highlight the significance of seasonal dynamics and local human influences in shaping the landscape of microplastic pollution. This study provides essential baseline data for environmental monitoring and integrated policy responses focused on reducing plastic waste, promoting environmental education, and ensuring the su