Microplastic particles are just as big a problem in subalpine lakes as they are in the ocean – how will this affect life in the freshwater lakes?
Researchers from German universities performed a study on pollution caused by microplastic particles in the beach sediments of lake Garda (subalpine region, Italy). The results showed that the level of contamination is comparable to that of marine ecosystems. This causes concern for the possible implications on freshwater biota.
Microplastic Particle Pollution
The pollution of the environment due to plastic wastes is a very serious problem, which is causing increasing concern. One of the dangers associated with plastic pollution is the formation of microplastic particles; these are relatively small plastic pieces, formed from the partial degradation of larger plastic objects. Microplastics have dimensions in the millimeters (mm). According to some researchers, microplastic particles have a diameter smaller than 1 mm; other people, however, consider a bigger diameter value of up to 5 mm.
Microplastics: Danger to the Environment
Several studies show the dangers that microplastic particles can cause to the environment; in the majority of these cases, however, researchers studied the level of pollution in marine ecosystems, and the consequent effects on marine biota (life). Little or no information is available on different environments, such as freshwater ecosystems.
Study on Subalpine Italian Lake Garda
Researchers from the University of Bayreuth (Germany) performed a study on the microplastic pollution of beach sediments from lake Garda, which is located in the subalpine region in the north of Italy. This lake is used as a supply of drinking water; moreover, it is one of the most popular tourist destinations, both for Italians and people from northern European countries.
The researchers worked in cooperation with the Technische Universität München and the Ludwig-Maximilians-University (Munich, Germany). They published the results in Current Biology on the 7th of October 2013. The study was part of a project which focuses on plastic and microplastic pollution of European limnetic systems (i.e. lakes and rivers).
Beach Contamination: Surprising Results
Professor Christian Laforsch, one of the scientists involved in the study, explains to Decoded Science what they found.
“We started our study from a subalpine lake, as we thought it would have been less polluted, especially with microplastics. The results, however, were very different, as we found a level of contamination comparable with that observed in marine beach sediments. To give some figures, on two beaches on the northern shore of the lake we detected 1108 ± 983 microplastic particles / m2. The southern shore was less contaminated, probably due to the ‘Ora’ north-south wind; still we found 108 ± microplastic particles / m2.”
To identify the materials the microplastics were made of, the researchers analyzed the fragments using Raman microspectroscopy; this is a technique which allows the characterization of materials at micron range. The spectra acquired were compared with those of either reference or commercial samples.
The main materials detected in these microplastics were low-density polymers, such as polystyrene (45.6 %), polyethylene (43.1 %) and polypropylene (9.8 %). Moreover, in the very smallest particles (dimensions between 9 and 500 microns), polyamide and polyvinyl chloride were also detected. These results are particularly worrying, as polyvinyl chloride is considered one of the five most toxic polymers.
Source of Microplastics
Where did all this plastic come from? Professor Laforsch told Decoded Science:
“These microplastics can come from various sources, such as rubble from landfills, illegal dumping and industrial activities; objects simply discarded in the environment may also be a source. In general, however, the majority of the particles we found came from post-consumer products. Some of the pieces we found may have come from plastic toys, water sport equipment, plastic bags and bottles, labels from the bottles themselves, etc.”
Implications for the Environment
The presence of microplastic pollution even in freshwater lakes such as Lake Garda holds significant implications for the environment. Professor Laforsch tells us:
“These results show that we have to reconsider some of our ideas about microplastic pollution. Until now, freshwater ecosystems such as lakes were considered mainly as a source of pollution for open sea / oceans; now we saw that they can also be sinks, at least temporarily. Considering the size of the microplastics, it is reasonable to assume that they can be uptaken by various limnetic organisms, similar to what happens in marine ecosystems. This can also lead to bioaccumulation and long-term consequences. It is therefore necessary to monitor carefully this contamination in freshwater systems.”
Plastic: Polluting oceans and freshwater ecosystems worldwide.
Imhof, H.K. et al. Contamination of beach sediments of a subalpine lake with microplastic particles. (2013). Current Biology, 23(19) R867-868.
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