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Microplastics in the sea: studies partially falsified by laboratory jacket material

Microplastics in the sea: studies partially falsified by laboratory jacket material



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Marine pollution: previous microplastic studies are sometimes dirty
Numerous studies have been published in recent years that show how polluted our oceans are. Now researchers point out that some investigations could be falsified by fibers from the laboratory coats of the scientists involved. However, this does not mean that plastic pollution of the world's oceans is harmless.

Plastics in oceans
Pollution in our environment is progressing every day. More and more waste is also ending up in the oceans. For example, plastic constantly gets into the oceans - from ships, from unsecured landfills, via waste water. According to scientific studies, plastic waste can now be found in all sea regions. Plastic waste has already been discovered in Arctic waters. However, researchers from Austria are now reporting that previous studies have often been unclean.

Contamination by natural fibers in the lab coats
For years it has been repeatedly claimed that a large part of marine plastic consists of tiny synthetic fibers - such as polyester or viscose. These particles are said to have been detected even at great depth.

In such examinations, however, you have to pay close attention to choosing the correct detection method, and this rule has often not been observed in previous studies, as an analysis by the Vienna University of Technology shows.

According to the experts, it was found that some measuring techniques cannot differentiate between natural and artificial microparticles.

In many cases, what was thought to be plastic from the environmental sample was simply a contamination by natural fibers in the lab coats.

The Austrian researchers recently published their new findings in the "Applied Spectroscopy" magazine.

If you measure, you also measure manure
"If you look for plastics in water samples, there is always the risk that the detected substances do not come from the sample itself, but from the laboratory environment," explained Prof. Bernhard Lendl from the Institute for Chemical Technologies and Analytics at Vienna University of Technology in one Message.

This problem was already known, which is why some research groups made great efforts to avoid synthetic fibers in the laboratory when plastic was detected in environmental samples.

According to the information, the experiments were carried out in special clean rooms, clothing made of synthetic fibers was prohibited. Otherwise, tiny fibers of clothing would inevitably find their way into the sample and falsify the result.

What was not thought of, however: viscose is a wood-based cellulose fiber that cannot be equated with plastic. In contrast to synthetic plastic, viscose consists of natural cellulose and is therefore biodegradable.

It is difficult to distinguish between synthetic fibers and natural cellulose fibers (e.g. viscose and cotton). If the correct analytical methods are not used, contamination by fibers in the cotton laboratory coat can also produce a result that can be mistakenly interpreted as evidence of plastic.

Similar falsifications in the laboratory had previously occurred with beer and honey samples - microplastics had also been found there, but later it was noticed that the results were probably due to unclean laboratory conditions.

Synthetic fibers at great depths?
The usual method for the detection of plastic traces in water samples is infrared spectroscopy. If the sample is illuminated with infrared radiation, some of the radiation is absorbed.

Different chemical substances absorb different areas of the infrared spectrum to different degrees, which means that different infrared fingerprints can be assigned to different chemicals.

"We examined various samples with precisely known content, using several different infrared spectroscopy methods," explained Lendl. This showed how easily errors can occur during such tests.

"If you choose the right method and carefully set the measurement parameters, you will certainly get reliable results, but with the technology that has been used to date, it is simply not possible to distinguish between synthetic fibers and natural substances," said the expert.

"According to our results, the synthetic fibers supposedly found at great depths are simply a measurement error."

Dramatic pollution of the world's oceans
However, this does not mean that plastic pollution of the world's oceans is harmless. There is indeed a great deal of plastic floating around in our oceans - from plastic bottles to lost fishing nets, there is no doubt about that.

"But when it comes to detecting microplastic traces, you have to choose the right scientific methods," emphasized Lendl. "Everything else is dubious and doesn't help the ocean or science."

It should also be noted that plastic parts have not only been found in water samples, but also in marine fish.

For example, scientists from the Alfred Wegener Institute (AWI) in Bremerhaven have detected plastic residues in edible fish from the North and Baltic Seas.

And marine researchers from East China Normal University in Shanghai reported in the American Chemical Society journal that they also found microplastics in sea salt. (ad)

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