“Very concerning” – Plastic waste: lakes more polluted than oceans

The research team led by Barbara Leoni and Veronica Nava of the University of Milan-Bicocca, which also included limnologist Katrin Attermeyer of the WasserCluster Lunz and the Department of Functional and Evolutionary Ecology of the University of Vienna, examined 38 lakes and reservoirs in a standardized research. According to the scientists, this is the first globally representative, standardized study of lakes.

94 percent microplastics
The sobering result: plastic waste was found in all the lakes surveyed – even in those waters that at first glance seemed completely untouched by human influence. Microplastics (particles smaller than five millimeters) made up by far the largest share at almost 94 percent, all other particles were larger.

Lunzer See in Lower Austria among 21 researched lakes
21 of the lakes examined showed concentrations of less than one particle per cubic meter. The only body of water in Austria that has been studied, the Lunzer See in Lower Austria, also belongs to this category. Fourteen lakes had concentrations between one and five particles per cubic meter and three lakes had concentrations of more than five particles. Attermeyer considers the results of these three lakes – Lake Lugano (Switzerland/Italy), Lake Maggiore (Italy) and Lake Tahoe (USA) – as “concerning because they already have a higher microplastic load than the world’s most polluted subtropical ocean currents.”. .

Chemically, most of the particles consisted of polyester (PES), polypropylene (PP) and polyethylene (PE), which does not surprise the expert: “PE and PP account for more than half of global plastic production, while PES accounts for 70 percent of all plastic production Fibers are needed for the textile industry.” Accordingly, two categories of shapes were dominant in the plastic particles found: fibers (49 percent) and fragments (41 percent), which form as “secondary microplastics” from the shattering of larger plastic parts.

Two types of water bodies that are sensitive to pollution
Two types of water bodies turned out to be particularly sensitive to pollution by microplastics: on the one hand, lakes in densely populated and urbanized areas, and on the other hand, large lakes that are probably extra polluted due to their large catchment area and long watercourses. residence time. The researchers found other connections: in lakes with a small surface area, maximum depth and shore length, blue or black fibers of PES predominated, while in large, deep lakes with extensive shores, transparent or white fragments of PP and PE predominated.

“Each lake had its own plastic signature, so to speak,” says Attermeyer. This could help not only identify potential sources of pollution, but also characterize the effects of plastic pollution.

In a second study published in the journal “Nature”, a research team led by Hudson Pinheiro of the California Academy of Sciences (USA) examined 84 coral reefs at various depths in the Pacific, Atlantic and Indian Oceans for anthropogenic macro-debris (larger than two centimeters). ). They found trash in 77 reefs, most of which were plastic. The proportion of plastic waste was highest in the deeper coral reefs (30-150 meters deep). In most of the areas surveyed, fishing was identified as the main source of plastic, such as fishing lines, nets or discarded baskets.