La Pineda beach registers the highest concentration of microplastics in Catalonia, Spain

The Pineda beach in Vila-seca (Tarragona) has by far the highest number of microplastics in Catalonia, according to a study led by experts from the University of Barcelona and the Universitat Rovira i Virgili published in the journal Marine Pollution Bulletin. The team has analyzed the 580 kilometers of Catalan coastline—from Cap de Creus to Vinaròs—and the data are clear: this beach accumulates up to 2,000 microplastics per kilogram of sand, a figure that is almost double that of the second on the list, a beach in the bay of Fangar, in the Ebro delta, with more than 1,100.

The results were not shocking, what strikes the most is that "the beaches of Barcelona, the most populated city in Catalonia, have lower concentrations of microplastics than other points further south between Castelldefels and Vilanova i la Geltrú or a large part of the coast of Tarragona," says Joaquim Rovira, a researcher at the Department of Basic Medical Sciences and the TecnATox research group at Universitat Rovira i Virgili (URV).

At the 70 points analyzed, samples were collected from the intertidal fringe—more than one sample was taken at the longest beaches—which is the area of wet sand between the point where the highest wave reaches the water level.

The size and chemical composition of the microplastics found were also analyzed according to their dimensions: large microplastics, up to 5 millimeters, identifiable to the naked eye, were mainly polyethylene and polypropylene, derived especially from the degradation of everyday objects such as plastic bottles or well-known industrial pellets. Small microplastics, smaller than 0.5 millimeters in size, are mainly found in textile fibers such as polyester and polyamide from laundry.

The study—the first such exhaustive one to be carried out on the coast of Catalonia—has analyzed 50 beaches along the Catalan coast, a sampling that has made it possible to obtain a very detailed X-ray of the state of microplastic pollution on the coast and to identify the most affected areas.

Microplastics everywhere

"The results were somewhat expected, since plastics are the most versatile and most abundantly manufactured materials after some building materials (cement, concrete, etc.). It should also be added that most plastics are persistent and not easily biodegradable, and when they are spread in the environment (through use, poor waste management, uncontrolled dumping, etc.) they tend to fragment, forming micro- and nanoplastics that are found everywhere," explain experts Esther Marí and Jordi Sierra, from the UB's Faculty of Pharmacy and Food Sciences.

"In studies, we have found them in inland water, seawater, sewage, drinking water, soils and sediments, food (mollusks) and even human feces. Other studies have revealed that they are even present in lung tissue, blood, some organs and even in the brain and human placentas. We dare say that plastics are probably the most abundant xenobiotic pollutants on Earth," warn the experts.

The most affected points

At La Pineda beach, which ranks highest in the ranking, an accumulation of plastic pellets—mainly from the petrochemical industry—was found, but the most alarming volume (more than 60%) is textile fibers, mainly polyester, which are not retained by the washing machine filters and reach the sea through the sewage.

"At this point they should be dispersed in the water, but the location of the submarine outfalls between the port of Tarragona and the cape of Salou prevents their dispersion," explains Rovira.

A significant concentration of microplastics was also found at the mouth of the Ebro River, especially in the Fangar bay, with more than 1,100 units per kilogram, which were washed in by the river. The beaches of Miracle and Arrabassada, in Tarragona, also recorded a high number of pollutants (more than 700 and more than 600, respectively), followed by the beach of Cala Vallcarca, located between Castelldefels and Sitges.

"We attribute this to the microplastics that reach the sea via the Llobregat River and travel to the southern beaches carried by the currents," explains the researcher.

The type of sand a determining factor

The study also shows how microplastics are distributed according to the characteristics of the sand. "On the Costa Brava beaches we detected less accumulation. We attribute this to the fact that the sand is coarser, and it does not retain as many microplastics as fine sand beaches," says Nora Expósito, a researcher in the URV's Department of Chemical Engineering.

A faster and cheaper technique

The study has also served to implement a technique that has not been used for sample collection until now, but which has proven to be reliable and more economical: the detection of microplastics by fluorescence. This system allows filters to be irradiated with a specific wavelength that makes the small plastic fragments glow, which facilitates faster and more visual detection.

Of all the samples obtained, one subset was analyzed with this new method and the other with the traditional spectroscopy-based system. After comparing the results, they found that fluorescence is a good method for an initial screening to identify the most contaminated areas.

More information:
Nora Expósito et al, Detection of microplastic hotspots in beach sand for national surveys using fluorescence microscopy and infrared spectroscopy: Case study on the Catalan coast, Marine Pollution Bulletin (2025). DOI: 10.1016/j.marpolbul.2025.117761

Provided by University of Barcelona