Clothing tag in the sea

Even more microplastics found in the deeper layer than assumed

The research project Deep Sea reveals: microplastics smaller than 1 mm have greater abundance on deeper layers (6-10 m) than in the surface samples. These surprising results of a research near Malta's shoreline have just been published by the project leaders. As part of the international team Dr. Gábor Bordós, project manager of the Eurofins Analytical Services Hungary Kft. laboratory told, that the accumulation of microplastics in the deeper layers might occur due to the change in their density, that shows possible contamination of the particles.

Microplastics (>1 mm) from the Mediterranean Sea, Malta shoreline (Image: Eurofins Analytical Services Hungary Kft.)

The goal of the project „Deep SEE” founded by The International Ocean Institute is to investigate microplastics at the shoreline of Malta. Samples were taken at 4 different locations around the island in different depth of the see: parallel to the surface sampling a Manta-net was also trawled in deeper layer in the same time to maintain similar environmental and technical conditions. (Zibel NGO played a very important role in the sampling process as technical support and contributor).

The resulting samples were then analysed by Eurofins Analytical Services Hungary Kft. a state-of-the-art environmental laboratory and show interesting data. Based on the results of the accredited laboratory significant differences are shown between the surface and the deeper layer samples regarding some polymers, especially the acrylic.

“Considering the currently available data and general assumptions this is a novelty that we found more microplastics (<1 mm) in the deeper layers (6-10 m) than in the surface samples” – said Ede Kossári‑Tarnik, researcher of the Malta University and grantee of The International Ocean Institute. This correlation did not occur in the case of microplastics over 1 mm.

Dr. Gábor Bordós, project manager of the Eurofins Analytical Services Hungary Kft. told that this distribution can be related to environmental conditions (e.g. salinity) and the properties of the polymers, such as density, size, shape and mass.

“As most of the plastics have smaller density than that of the sea water, we can assume, that the cause of their sinking – further to waves and currents – is the change in their relative density. This can be caused e.g. by biofouling which means microorganisms and other contaminants stick to the surface of the microplastics”.

Another research project with participation of the Eurofins Analytical Services Hungary Kft. investigates this issue too and focusing on the distribution of microplastics with potential human health risks in indoor, workplace and ambient air samples, including their microbiological effects and the capacity to adsorb harmful chemicals in the water environment.

These studies are important as there are knowledge gaps currently. Dr. Gábor Bordós and his colleagues showed during The Tiny Plastic Puzzle, a previous research of Eurofins in Hungary, that microplastics are found in freshwaters (50 particles/m3 were identified in the Danube River at Budapest), but it is crucial to reveal the overall contamination and the potential risks.

What polymer types has been identified? Where do they come from?

The identified microplastics have different shapes, density and mass: the majority of the particles were between 50-350 µm in size and the most abundant polymer types were acrylic (42,9%), polyethylene (17,3%), polypropylene (15,7%) and polystyrene (10,5%). Acrylic polymers are widely used in the clothing industry (fibres), in “plexi” sheet (PMMA: polymethyl metacrylate) and in paints, coatings. Other dominant polymer types in the sample can originate from several sources as these are common from the packaging industry to the building and construction sector.

One would ask, how diverse are the microplastics brought to surface by the researcher? Dr. Gábor Bordós shows a small, whitish, star-shaped fragment: this might be originating from a plastic cloth tagging pin.

Microplastic particle originating suspectedly form a cloth tagging pin. (Image: Eurofins Analytical Services Hungary Kft.)

This particle highlights, that even if consumers are environmentally conscious and collect their waste separately, tiny plastic pieces inevitably enter the environment. It is important to review on the manufacturers and legislation side, which plastic items in our daily life call for urgent replacement by more sustainable alternatives.

This research project has been made possible through a joint collaboration between the University of Malta, Oceanography Malta Research Group (Prof Alan Deidun, Dr Adam Gauci, Ede Kossari Tarnik ), Zibel, Environmental NGO (Andrew Schembri, Arkadiusz Srebnik) and Eurofins Analytical Services Hungary Ltd. (Dr Gábor Bordós, Bence Prikler). The same research has been part-supported by the Elisabeth Mann Borgese Bursary of the International Ocean Institute which has been awarded to Ede Kossari Tarnik for 2022-23. Nora Kovats and Michael Bonello (DUTCH) also participated in the project as creative contributors.