Tracking Microplastics in Paradise: First Evidence of Pollution in Lençóis Maranhenses National Park (Maranhão, Brazil), a UNESCO World Heritage Site

Microplastic (MP) pollution is a growing environmental threat to vulnerable ecosystems, including the Lençóis Maranhenses National Park (LMNP), a UNESCO Natural World Heritage Site. This study provides the first assessment of MP presence, characteristics, and potential sources in this region. A total of 92 sand sediment samples was collected along 95.3 km of beaches across three zones: inside the LMNP (area 1), adjacent to the park (area 2), and a more distant coastal zone (area 3). Samples underwent flotation, filtration, and chemical digestion, and MPs were characterized by morphology and composition. Principal component analysis (PCA) was employed to explore associations between environmental factors and MP concentrations, while dispersion modeling based on ocean currents and wind patterns identified likely transport routes. MPs in the LMNP exhibited high variability in size, color, and polymer types, including uncommon materials like poly(ether–ether–ketone) (PEEK). PCA results indicated a strong influence of anthropogenic drivers, especially proximity to urban areas and tourism. Area 2 emerged as a key MP source. Spectral analysis revealed chemical similarities between MPs from areas 1 and 2, corroborating modeled transport connections. These findings offer critical baseline data for MP pollution in LMNP and inform future conservation and waste management strategies.