Shocking: Arctic sea contain 10 times more microplastics than seawater

Melosira arctica, a species of algae found in Arctic sea ice, has been found to contain microplastic particles in concentrations ten times greater than those present in the surrounding seawater, according to a study from the Alfred Wegener Institute published in the journal Environmental Science and Technology.

This discovery is worrying as it poses a significant threat to marine animals that depend on algae as a food source, both on the sea surface and in the deep sea.

Melosira arctica is a critical component of the arctic ecosystem. It undergoes rapid growth under sea ice during spring and summer, forming long chains of cells. When the algae die, they clump together as the ice melts, and these clumps can sink thousands of meters to the depths of the sea floor in a single day. These aggregates are a vital food source for bacteria and bottom-dwelling creatures.

However, a research team led by Dr. Melanie Bergmann discovered that these clumps of algae also contain microplastics. This finding helps explain why the highest concentrations of microplastics are consistently found in the ice-edge area, even in deep-sea sediments.

What the study found about Arctic sea ice

Previous research had suggested that microplastics accumulate in sea ice during its formation and are later released as the ice melts into the surrounding water. However, new findings suggest that Melosira arctica, due to its fast sinking speed, plays a significant role in transporting microplastics directly to the deep sea floor, primarily under the ice edge.

Dr. Melanie Bergmann, who led the research team, explained that while marine snow gets pushed sideways by currents and sinks further away, the Melosira algae's fast sinking speed causes it to descend almost directly below the ice edge, thereby taking microplastics directly to the bottom.

During a summer 2021 expedition aboard the research vessel Polarstern, the team collected samples of Melosira algae and surrounding water from ice floes and analyzed them for microplastic content.

The surprising results showed that the algae clumps contained about ten times more microplastic particles (an average of 31,000 ± 19,000 microplastic particles per cubic meter) than the surrounding water.

The analysis was conducted in collaboration with partners from the Ocean Frontier Institute (OFI), Dalhousie University, and the University of Canterbury.

An important food source polluted

As ice algae serve as a crucial food source for many deep-sea organisms, microplastics carried by Melosira arctica can potentially enter the food web, affecting not only deep-sea creatures but also those at the surface of the ocean sea.

Previous AWI studies have shown that microplastics are particularly widespread among ice-associated zooplankton, which may explain their entry into the food chain.

A detailed analysis of the plastic composition found in the Arctic revealed several types of plastics, including polyethylene, polyester, polypropylene, nylon, and acrylic, among others, that create a complex cocktail of substances, chemicals, and dyes. The overall impact of this cocktail on the environment and living things remains difficult to assess.

Melanie Bergmann warned that people in the Arctic who rely on the marine food web for their protein supply, such as hunting or fishing, are also exposed to microplastics and the chemicals it contains.

Microplastics have already been detected in human organs such as the intestines, blood, veins, lungs, placenta and breast milk, causing inflammatory reactions. However, the general consequences of this exposure remain largely unexplored.

Steve Allen, another study co-author, added that micro- and nanoplastics have been detected in virtually every place scientists have observed in the human body and in a plethora of other species. Plastic chemicals are known toxins to humans and can change behavior, growth, fecundity, and mortality rates in organisms.

Arctic Algae Harbors Microplastics Threat

The Arctic ecosystem is already facing significant threats from the climate crisis, and the presence of microplastics and the chemicals they contain may further weaken organisms in the region.

People living in the Arctic, who depend on marine food webs for their protein supply through hunting and fishing, are particularly exposed to these pollutants.

Microplastics have been detected in various parts of the human body, including the intestines, blood, veins, lungs, placenta, and breast milk, and can cause inflammatory reactions.

Micro- and nanoplastics have been found to modify the behavior, growth, fecundity, and mortality rates of organisms, and many plastic chemicals are known toxins to humans.

The complex mix of substances found in the Arctic, including different types of plastics and various chemicals and dyes, makes it difficult to fully assess the impact of these pollutants on the environment and living things.

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