As plastic, single-use containers, cups, bags, straws and other disposable items continue to fill landfills and waterways around the world, global concern over the effect of microplastics on health – the end result when these items degrade – is higher than ever, but it’s only recently that progress has been made in accurately assessing the problem.
Japan-based researchers have a new method for estimating microplastic concentrations, making resource use more efficient, sampling more precise and problem assessment more meaningful, according to recent research by a team of Tokyo University of Science.
The new study was carried out by University of Tokyo researcher Mamoru Tanaka and fellow researcher Yasuo Nihei, as well as Ehime University researcher Tomoyah Kataoka, according to team spokesperson Hiroshi Matsuda. The team proposed a method that estimates sampling requirements for an accurate assessment of microplastic contamination in rivers.
The study, “Variance and Accuracy of Microplastic Sampling in Urban Rivers,” was published in the journal “Environmental Pollutions,” an international peer-reviewed journal that publishes high-quality research articles and articles. summary on all aspects of environmental pollution and its consequences. effects on ecosystems and human health. Since that publication, the work has been reviewed by many other scientific journals.
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The study hopes to improve the accuracy of studying the problem of microplastics and its effects on humans by helping to standardize sample collection protocols, according to Tanaka.
“Most studies of river microplastics do not provide the accuracy of their microplastic concentration estimates,” Tanaka said in an email response to questions from the Chattanooga Times Free Press. “Our work proposes how to assess, calculate or predict the accuracy of their estimates.”
The extent of plastic pollution remains largely hidden in the form of invisible microplastics, according to the team.
“In the years since their discovery in the early 1970s, microplastics have become a pervasive and global concern,” Matsuda said in a press release about the study. “Microplastics are found in the earth, air, water, and the foods we eat, especially seafood.”
Microplastics are present in seafood because freshwater sources, such as rivers, transport microplastics to the oceans, where they accumulate, according to the team.
The team collected 10 samples in plankton nets at two sites along the Ohori River and the Tone-unga Channel in Chiba, Japan – two bodies of water that flow through urban areas and contain a high concentration of litter plastics – according to Matsuda.
The team found that at high concentrations of microplastics, two replicate samples are enough for an accurate measurement.
Research on the rise
It’s only been in recent years that scientists have turned their attention to microplastics, but they’ve been present in the environment – and in the Tennessee River – for decades, according to research from the University of Tennessee at Knoxville, the Tennessee Valley Authority, the University of the South in Sewanee, Tennessee, and others. Scientists around the world are concerned that microplastics may act like supermagnets, absorbing concentrated amounts of airborne toxins in public drinking water sources.
A 2019 study published in the peer-reviewed scientific journal “Environmental Science and Technology” estimated that Americans each consume 39,000 to 52,000 microplastic particles per year.
The Tennessee River is a prime example of microplastic pollution.
For 34 days in the summer of 2017, German scientist and long-distance swimmer Andreas Fath set a world record by swimming the 652 miles of the Tennessee River, end to end, with equipment to collect water samples. The idea was to draw attention to the problem of microplastics in what was then dubbed “TenneSwim”.
Fath, a professor of medicine and life sciences at Germany’s Furtwangen University, presented his first findings at the Tennessee Aquarium Conservation Institute in 2018, comparing results from samples taken from the German Rhine – which Fath swam in 2014 for analysis – in Tennessee. River, which turned out to be much more polluted.
“We found a bunch of different chemicals from households, industry and agriculture in the Tennessee River, along with a large amount of microplastic particles ranging in size from 25 to 300 [microns]“, said Fath in 2021.
Fath noted that microplastics have even been found in Lake Toma in Switzerland at an elevation of 7,677 feet.
Compared to the German Rhine with 0.2 particles per litre, the Tennessee River’s concentration is around 90 times higher, Fath said in 2021. China’s Yangtze River has around 9 particles per litre, about half the concentration of the Tennessee River, according to Fath. results. But it’s hard to really determine how different rivers compare because of so many variables, he said.
Martin Knoll, professor of geology and hydrology at Sewanee, helped lead the TenneSwim survey with Fath and determined that about half of the microplastic pollution in the Tennessee River is polyethylene, the material used to make grocery bags.
Knoll’s research into the microplastics problem is a work in progress, and he said meaningful research into the problem is in its infancy.
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“The big problem with researching microplastics in water is that there is no standard methodology,” Knoll said Friday in a phone interview between classes. “This makes it very difficult to compare the results of one study with the results of another study.”
But while the Japanese study is a small step forward for assessment accuracy and has solid analysis, the methodology may have only limited potential in the United States, where some rivers are deep and not not ideal for the Japanese approach to surface sample collection, Knol said. The Japanese study’s use of plankton and neuston nets also fail to capture the smallest microplastic particles, he said.
According to the National Oceanic and Atmospheric Administration, neuston includes insects such as whirling beetles and water striders, some spiders and protozoa, and occasionally worms, snails, insect larvae, and surface-dwelling hydras. some water.
The state of California is using what could become the new appraisal standard, according to Knoll. California defines microplastics as “solid polymeric materials” measuring between one thousandth of a millimeter and 5 millimeters, according to California’s State Water Resources Control Board. Knoll said the catch nets used in California are sized appropriately for the smallest particles.
Knoll said the new sampling methodology used in California stems from recent legal requirements passed by lawmakers there to test for microplastics in drinking water and report the results to the public. He said the sampling methods used in his work in Sewanee are almost identical to those in California.
“In the United States — and probably the world — I think the California way is going to be dominant,” Knoll said. “The reason California is doing this is they’re going to regulate microplastics in drinking water.”
The California method has yet to be adopted anywhere else except for some independent labs like Knoll’s in Sewanee, he said.
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Reduce error range
The new Japanese method has not been employed by others either, Tanaka said. The team felt that plankton nets and neuston nets were the norm for most researchers, worldwide, and the aim of the new study is to reduce the range of error in the results, making it difficult comparing the accuracy of estimates in other studies, according to Tanaka.
“Here, our method indicates how much researchers need to repeat netting sampling to get accurate estimates of the concentration of microplastics in the river, based on scientific and statistical evidence. So far, there is no had no method to ‘scientifically’ determine the number of repeats until our published paper,” Tanaka said. “Our established method for microplastic collections by plankton nets and neuston nets may be applicable for studies of microplastics in the United States and elsewhere.”
Tanaka said various countries, including Japan, have passed legislation to provide better monitoring and control of microplastics in the environment.
Although new, Tanaka hopes the team’s methodology will be incorporated into standards for future microplastics sampling while reducing the time and resources invested in microplastic assessment surveys.
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Meanwhile, Knoll said he was planning a trip to Europe’s Danube – which flows from the Black Forest in Germany to the Black Sea between Turkey and Ukraine – to collect samples from its deepest points in order to to assess microplastic contamination. He said Fath had recently swum in the river to collect samples from the surface.
Research into the microplastics problem is gaining momentum in the scientific community, he said, and improvements and new developments are expected to become more frequent and bring benefits to humans.