Su Lei does biological sample (shrimp) digestion experiment Photo by Gao Yang
Reporter Gao Yang
Today is World Oceans Day, the theme is "Protect the marine ecosystem, harmonious coexistence between man and nature", protecting ecology and harmonious coexistence, should be the meaning of the title. Our reporter recently walked into the Organic Pollutant Toxicology Laboratory of Shanghai Ocean University and listened to Su Lei, associate professor of the College of Marine Ecology and Environment, talk in detail about the true side of marine microplastics...
We can often see examples of seabirds dying tragically after eating colorful plastic, and humans naturally do not find a piece of plastic to chew and swallow. However, scientists have long found that plastics and even microplastics are widely present in the bodies of fish and in seawater.
In recent years, the topic of microplastics has heated up rapidly internationally, and with it, there is a panic about microplastics. Today is World Oceans Day, our reporter saw Associate Professor Su Lei doing a digestion experiment on sea shrimp in the Organic Pollutant Toxicology Laboratory of Shanghai Ocean University, and listened to his analysis and explanation, and learned about the latest research progress of marine microplastics.
"We see plastic in the environment almost every day, but often walk into a store and forget about its potential environmental hazards. The only way to reduce microplastics in seawater is to reduce plastics. Su Lei said.
Microplastics into the fish?
The experimental results are not the same as "taking it for granted"
Plastic, which "shapes" the way we live, is a cheap, durable, readily available material that plays a huge role in almost every field such as healthcare, construction, packaging, energy, etc.
But a set of figures is also worth paying attention to - the United Nations Environment Programme said: the world produces more than 400 million tons of plastic every year, one-third of which is used only once; Less than 10% of plastic is recycled, and at the same time, 10 million tons of plastic waste enters the ocean every year, constituting marine plastic pollution.
The concept of microplastics was first proposed in 2004 by Professor Thompson of the University of Plymouth in the international top academic journal Science. "Microplastics are substances formed when plastic products decompose in the environment, usually referring to plastic particles, fibers or debris with a particle size of less than 5 mm." Su Lei explained, "Many microplastics can reach the micron or even nanometer level invisible to the naked eye, so it is also known as 'PM2.5 in the ocean'." ”
As scientists have discovered microplastics in the inaccessible Mount Everest, Mariana Trench and Antarctica, humans can no longer be calm, and more and more research on microplastics as the keyword. Researchers from Newcastle University in Australia even said that "the microplastics we swallow every week are as heavy as a credit card" - shocking enough! In the end, researchers found evidence that microplastics entered the human body.
Su Lei told reporters that there are three main sources of marine microplastics, one of which is discharged into the marine environment through rivers and sewage treatment plants; the second is a considerable amount of fishery waste; The other, more special, is transportation to the marine environment through the atmosphere.
"Microplastics have a small particle size and light density, which can carry out long-distance and wide-range migration, and microplastics are widely distributed in all corners of the marine environment." He added.
International studies have shown that of the 504 fish from the English Channel, 36.5% have microplastics in their digestive tracts. Of the 385 barnacles collected in the North Pacific Subtropical Gyre, 33.5% of individual digestive tracts contain microplastics... Can we still laugh and say the phrase "I want to eat fish"? Hearing the reporter's question, Su Lei stopped the experiment in his hand and shook his head: "We have a misunderstanding of microplastics entering the fish body."
In the past 20 years, marine microplastics research has entered a period of rapid development, and this "new wine" has filled or even begun to overflow the "old bottle" of "marine garbage". Indeed, after marine microplastics enter the food chain, they may eventually return to the human body, which is why the popularity of microplastics research is "always on".
"Marine microplastics and organisms at lower trophic levels in the ocean, such as plankton, have similar sizes and densities, and the biofilm on their surface can also make marine organisms indistinguishable and susceptible to ingestion." Su Lei pointed out.
Studies have shown that organisms "feed" microplastics in various ecological niches of marine ecosystems, including marine zooplankton, benthic animals, fish, birds and even large mammals. In addition, in addition to active behavior, microplastics can also enter the organism through behaviors such as adhesion or breathing.
According to Su Lei, the current global marine fish survey on microplastics shows that each fish ingests about 1 microplastic individual on average. "These research data are generally based on fish gastrointestinal analysis, but as the investigation deepens, people pay more attention to the mechanism of microplastics ingestion by wild fish and the fate of microplastics in the environment outside the digestive tract of fish." He said.
More or less, people know the term "enrichment" through various channels, so is aquatic products really a threat to us? The organic pollutant toxicology laboratory led by Su Lei seems to have different experimental results than "taken for granted" -
"Fish sampling studies based on the estuary of the Yangtze River have found that the current level of contamination of microplastics in the edible part of fish is likely to be overestimated." Su Lei gave a set of data: there are only 1-2 microplastics "fish average" in the fish near the Yangtze River estuary, and the content is not high. "Moreover, these microplastics are mainly concentrated in the gastrointestinal tract and gills of fish." He pointed out that in the case of sea bass, microplastics above 20 microns cannot be detected in edible parts such as muscles at all - that is, unless you regularly eat a large number of non-mainstream dishes such as stir-fried fish belly or gills, the probability of ingesting microplastics in fish through direct eating is very low.
Interestingly, kelp, seaweed, etc., which seem to be quieter, can also detect microplastics, because the polysaccharides contained in algae are more likely to adhere to microplastics.
Su Lei told reporters that indoor experiments have proved that fish also "don't like to eat" plastic. The evidence is that fish respond by vomiting and coughing, excreting microplastics and preventing them from entering their bodies. "Through fluorescent staining tracking, some microplastics are also carried out of the body by fish excrement." However, he also stressed that the conclusions obtained by the laboratory still need to be supplemented by field experiments.
Rely on data
A stronger "Chinese voice"
An important work of the Organic Pollutant Toxicology Laboratory is to carry out the investigation of the current situation of microplastic pollution in multi-environmental media, and has achieved a series of research results.
"From the analysis of Shanghai's coastal water, a certain amount of microplastics was indeed detected in the river. However, compared with the rivers of developed countries in Europe and the United States, this data is at a medium and low level. Professor Li Juanying, vice dean of the university's graduate school, pointed out.
However, some Western scholars do not think so. Because there has long been no internationally agreed monitoring method for the flux of plastics and microplastics into the sea, the amount of plastic waste entering the sea in China is seriously overestimated, and there is even a claim that China's Yangtze River is the world's largest river that emits plastic waste and microplastics into the ocean - and these views are not supported by measured data.
In fact, microplastics research was once mixed with confusion, fallacies and false rumors. But to reverse those absurd arguments, you must rely on data. The reporter learned that at the beginning of 2017, the first batch of projects in the field of "marine environmental security" "marine microplastics monitoring and ecological environment effect assessment technology research" was launched in Shanghai, mainland scientists have successively established an estimation model of China's plastic waste into the ocean output, and for a long time in the mouth of the Yangtze River and adjacent seas to carry out the monitoring of suspended microplastics...
A series of true and accurate scientific data were disclosed at important international conferences, which strongly refuted the erroneous view of Western scholars that "China is the largest source of plastic waste entering the sea among the world's coastal countries", and the research results of Chinese scientists have gradually been internationally recognized.
"In the 'golden age' of microplastics research, the number of institutions carrying out related research on the mainland is also increasing year by year, and researchers have traveled all over the offshore ocean." Li Juanying said proudly.
In Shanghai Ocean University, a number of scientific research teams of the university have also made progress in the field of marine microplastics and have been published in international authoritative journals: Wang Youji's team from the College of Fisheries and Life Sciences took Hangzhou Bay as a typical representative area to clarify the impact of geospatial development and utilization patterns on the distribution of microplastics; Yu Fei's team from the School of Marine Ecology and Environment systematically summarized the influence of environmental factors on the physical and chemical properties of microplastics and the enrichment behavior mechanism between micro/nano plastics and heavy metals and organic pollutants...
"We will continue to look for field evidence of the harm of microplastics and obtain effective indoor toxicology data to further understand the ecological and health hazards of microplastics." Su Lei said, "I hope to use more and more powerful scientific data to make more Chinese voices in the field of marine microplastics and strive for international discourse." ”
Plastic reduction is the only way
"Plastic microbeads" have been controlled by legislation in many countries
Although laboratory studies have shown that the probability of microplastics entering the muscles of fish and being ingested by humans is low, it is clear that the topic of marine microplastics cannot stop at the word "eat".
"Plastics and microplastics themselves have toxic effects on fish, including physically entanglement and blockage of the digestive tract or malnutrition. If the use of plastic products is not restricted, it is likely to cause problems in the structure of fish stocks and even reproduction. Su Lei pointed out.
He admits that today's science and technology cannot eliminate microplastic pollutants in the ocean at low cost, high efficiency and on a large scale - after all, microplastics are not as easy to pick up as large pieces of plastic. The only way to reduce the entry of microplastics into the sea is to reduce the use of unnecessary plastic products.
In fact, many scientists at home and abroad have called for everyone not to abuse plastic products in their lives and try to choose degradable plastic products; And doing a good job of garbage classification is also conducive to reducing the harm of microplastics.
Su Lei also specifically named "plastic microbeads" - as a scrub material, it is intentionally added to personal toiletries, cosmetics, drugs and other products, and has been controlled by legislation in many countries around the world. "When choosing personal care products, you should also pay attention to the ingredient list, and try not to use products with plastic scrub ingredients."
In Shanghai, countless people have taken action, non-governmental environmental protection organizations regularly carry out "beach clean-up operations" to collect all kinds of waste on the beach, multinational companies have announced that they will abandon the use of microplastics in cosmetics... "I hope that invisible microplastics will not become the 'new killer' of human health." On World Oceans Day, Su Lei made such a wish.
Source: Xinmin Evening News