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First Evidence of High Microplastic Concentrations in Estuarine Litter Windrows of a World Heritage Site: The Paranaguá Estuarine Complex, Brazil

Water Air & Soil Pollution 2025 5 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Allan Paul Krelling, Fernanda Eria Possatto, Gabrielly Rodrigues Anhaia Maia, Koiti Araki, Guilherme Bordin Ranea Olivieri, Helton Pereira Nogueira

Summary

Surface water sampling across the Paranaguá Estuarine Complex, a UNESCO World Heritage Site in Brazil, detected microplastics throughout the system, with estuarine litter windrows acting as accumulation hotspots at nearly ten times the average estuarine concentration. The presence of microplastics at a protected World Heritage site demonstrates that plastic pollution respects no conservation boundaries, and that windrow dynamics are a key driver of MP hotspot formation in transitional coastal ecosystems.

Polymers

Transitional ecosystems, such as estuaries, are among the most susceptible regions to plastic pollution. The objective of this project is determining the occurrence and spatial distribution of Microplastics (MPs) and the presence of litter windrows as potential hotspots of MPs on the water surface of a subtropical estuarine complex. In 2022, 14 surface water (< 0.20 m) samples were collected with a trawl net called NOIVA. Each trawl was carried out at a speed of 5 km/h, for 5 min, always on the neap tide, along the Paranaguá Estuary Complex (PEC). In the laboratory the samples were sieved through 1 mm stainless steel mesh. The items were visually inspected through a stereomicroscope to select potential microplastics. The hot needle test and attenuated total reflectance Fourier transform infrared was applied to confirm the composition of items. Statistical analyses were performed (PERMANOVA and CAP). A total of 40 MPs were found in all sectors. Fragments are the most frequent (70%). Secondary MPs represented 95% of the items, among which the most common are 3–4 mm large (35%) and white (27.5%) particles. Polypropylene (PP) was the most common type (42.5%). The average concentration of MPs in the PEC (0.149 ± 0.37 mp/m3) is comparable to that found in other estuaries. Estuarine litter windrows (ELWs) play an important role in the accumulation of floating MPs in the PEC (1.42 mp/m3). The omnipresence of MPs at a World Heritage Site is alarming. There is an urgent demand for pollution control, especially regarding adequate waste management strategies to reduce the presence of marine litter.

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