Microplastics Widespread on Catalan Beaches, Study Finds

In a recent study published in Marine Pollution Bulletin, a team of researchers from several Spain and Portugal universities and institutions (Rovira i Virgili University, Universitat de Barcelona, University of Porto, and Institut d'Investigació Sanitaria Pere Virgili (IISPV) assessed microplastic (MP) contamination along the Mediterranean coastline. This study, conducted in northeast Spain, investigated a 580-kilometer stretch of beach, examining beach sediments for MP contamination (1).

The Catalonia coastline is considered by some to be one of the most beautiful stretches of beach in the entire world (2). As a result, this coastline receives many tourists annually, which leads to a lot of foot traffic. Because of visitors and general human activity, it is probable that waste, especially plastic waste, serves as a significant threat to this coastline and its ecosystem. However, there has not been much current research that has studied this issue in depth.

Beach and Village of Calella, Costa del Maresme, Catalonia, Mediterranean Sea, Spain. | Image Credit: © travelpeter - stock.adobe.com

As a result, Esther Marti led a research effort to provide more information about MP contamination along the Catalonia coastline. As part of the experimental procedure, the research team collected and analyzed seventy (n = 70) intertidal sand samples to characterize MPs in the range of 60 μm to 5 mm (1). The study considered a wide array of environmental and anthropogenic factors, including sand size distribution, geomorphology, meteorological parameters, and human activities, to better understand MP distribution (1).

To ensure accurate detection and characterization, the researchers employed both traditional and novel analytical techniques. The larger MPs fraction (above 0.5 mm) was separated by dry sieving and subsequently analyzed using visual sorting and Fourier-transform infrared (FT-IR) spectroscopy (1). For MPs smaller than 0.5 mm, a wet density separation process was used, followed by oxidation of organic matter (1). These samples were then analyzed using Nile Red staining and fluorescence microscopy. A subset of samples (n = 23) was also subjected to micro-FT-IR (μ-FT-IR) techniques to validate the staining method’s accuracy (1).

Although μ-FT-IR remains essential for confirming MP composition, fluorescence microscopy using Nile Red staining presents a promising screening technique for detecting hotspots of MP pollution. This alternative method could be particularly useful for large-scale monitoring projects, providing rapid and cost-effective preliminary assessments before detailed spectroscopic analyses (1).

MP concentration varied between the different beaches along the Catalonia coastline. When averaged, the researchers determined a mean level of 388 ± 367 MPs/kg across all sites (1). MPs larger than 0.5 mm were found in concentrations ranging from <0.55 to 56.8 MPs/kg, with fragments accounting for 60% of this fraction (1). These MPs primarily consisted of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS). The one thing these materials have in common is that they are all used in packaging and consumer goods, which indicates that human activity is a significant reason why MPs are found on the Catalonia coastline.

For the smaller MPs fraction (60 μm - 0.5 mm), concentrations ranged from 0 to 2013 MPs/kg, with fibers constituting 70% of this category (1). The most detected fiber types were polyester (PES), polyamide (PA), PP, and acrylic (PAN), highlighting the contribution of textiles and synthetic fabrics to coastal pollution (1).

There were a couple of smaller observations the researchers noted in their conclusions. For one, the research team noted MP concentrations correlated strongly with sand particle size (1). However, they also noted that there was a weak correlation between MP concentrations and other environmental variables such as geomorphology or meteorological conditions (1). Instead, human-derived factors, including sewage treatment plant discharges, surface runoff, and local ocean currents, were identified as likely contributors to MPs accumulation along the coastline (1).

This study underscores the importance of monitoring programs that utilize both traditional spectroscopic methods and innovative fluorescence staining techniques for more efficient data collection. Given the significant presence of synthetic fibers, researchers suggest that measures to reduce textile-based pollution—such as improved filtration in washing machines and wastewater treatment facilities—could be crucial in mitigating the spread of MPs (1).

References

1. Exposito, N.; Sierra, J.; Marti, E.; et al. Detection of Microplastic Hotspots in Beach Sand for National Surveys Using Fluorescence Microscopy and Infrared Spectroscopy: Case Study on the Catalan Coast. Mar. Poll. Bullet. 2025, 214, 117761. DOI: 10.1016/j.marpolbul.2025.117761
2. Butler, S. Traveller’s Guide: Coastal Catalonia. The Independent. Available at: https://www.independent.co.uk/travel/europe/traveller-s-guide-coastal-catalonia-8589543.html#:~:text=Political%20and%20cultural%20differences%20aside,almost%20come%20across%20as%20undiscovered. (accessed 2025-03-26).