Microplastics in mangrove sediments in environmental protection areas of the south coast of Pernambuco, Brazil

This study evaluated the microplastic (MP) contamination and its ecological risks in sediments from two estuarine complexes under different anthropogenic pressures (Formoso River and Ilhetas-Mamucabas), both located within Marine Protected Areas (MPAs) on the southern coast of Pernambuco, Northeast Brazil. Samples were analyzed for type, size, and polymer composition via FTIR spectroscopy. The Formoso River estuary presented the highest abundances (up to 800 items.kg), associated with low sanitation coverage (40.2%). Distinct pollution signatures were identified, with predominance of fibres (100-200 μm) in areas influenced by fishing and sewage (R1), and of fragments in regions influenced by agricultural waste (R2). The risk assessment revealed a notable divergence: despite the low Pollution Load Index (PLI), the Polymer Risk Index (H) was classified as "Very High Risk" at sites with PVC and PU presence, indicating that abundance can obscure the real chemical hazard. By contrast, the Ilhetas-Mamucabas complex exhibited less contamination and a predominance of larger MPs (>200 μm). MP accumulation was positively correlated with sediment mud content. The findings demonstrate the vulnerability of MPAs and highlight that assessing chemical risk, beyond abundance, is crucial for effective environmental management of plastic pollution.