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Zooplankton are rapidly escalating the threat of marine nanoplastics

A team of researchers led by the University of Massachusetts Amherst have uncovered a significant environmental threat: zooplankton are rapidly escalating the presence of nanoplastics in both ocean and freshwater ecosystems.

Focus of the study 

The study focuses on rotifers, microscopic zooplankton prevalent in various water bodies. These tiny organisms have been found to break down microplastics into nanoplastics, particles smaller than one micron. 

Shockingly, a single rotifer can generate between 348,000 to 366,000 nanoplastic particles per day. In Poyang Lake, China’s largest freshwater lake, this number escalates to 13.3 quadrillion particles daily.

Global plastic problem

Plastics, known for their durability, pose a significant environmental challenge, taking up to 500 years to decompose. Over time, larger plastic items degrade into microplastics, which have been detected globally from Mount Everest to the Mariana Trench. 

Alarmingly, microplastics have also been found in human blood and heart tissue. When microplastics are further broken down into nanoplastics, this increases their number exponentially.

The danger of nanoplastics

Nanoplastics, due to their smaller size, have a greater surface area, making them more reactive and potentially more harmful than microplastics. They can spread easily and are difficult to track. 

The study highlights a gap in the understanding and research of nanoplastics, particularly in their creation and abundance.

How are nanoplastics produced?

Baoshan Xing, the senior author of the paper and a distinguished professor at UMass Amherst, emphasized the lack of effective recycling methods for plastics. 

“Humans produce enormous amounts of plastics, and yet we don’t have an effective way of recycling them,” said Professor Xing. “We began to wonder about nanoplastics and especially how they’re produced.”

The study was spurred by curiosity about the role of living creatures in creating microplastics, a question that arose after observing similar behaviors in Antarctic krill. The researchers were particularly interested in rotifers.

“Whereas Antarctic krill live in a place that is essentially unpopulated, we chose rotifers in part because they occur throughout the world’s temperate and tropical zones, where people live,” explained Xing.

The role of rotifers 

There are around 2,000 different species of rotifers worldwide, and they are very abundant. In one lake, the experts found approximately 23,000 individual rotifers in every liter of water

Rotifers possess a specialized masticatory apparatus, enabling them to grind microplastics into smaller particles. The team exposed both marine and freshwater species of rotifers to a variety of different plastics of different sizes.

The researchers discovered that rotifers could ingest microplastics up to 10 micrometers in size and excrete thousands of nanoplastics back into the environment. They estimate that rotifers could produce 13.3 quadrillion nanoparticles every day, just in Poyang Lake alone.

Study implications 

Professor Jian Zhao, the paper’s lead author, noted that this study reveals a new route for the production and generation of nanoplastics worldwide. 

“We show for the first time the ubiquitous fragmentation of microplastics by rotifers,” said Professor Zhao. “This is a newly discovered route to produce and generate nanoplastics in both freshwater and seawater system worldwide, in addition to well-known physical and photochemical fragmentations.” 

“This finding is helpful for accurately evaluating the global flux of nanoplastics. In addition, it is known that nanoplastics can not only be potentially toxic to various organisms, they can also serve as carriers for other contaminants in the environment. Furthermore, the release of chemical additives in the plastic can be enhanced during and after the fragmentation.”

“Our work is just the first step,” said Xing. “We need to look at other organisms on the land and in water for biological fragmentation of microplastics and collaborate with toxicologists and public health researchers to determine what this plague of nanoplastics is doing to us.”

The study is published in the journal Nature Nanotechnology.

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