Improperly discarded surgical masks threaten the marine ecosystem and the food chain


Improperly discarded surgical mask on the coast of Hong Kong. Credit: City University of Hong Kong

Surgical masks have been part of essential personal protection during the COVID-19 pandemic. However, improper disposal of surgical masks can cause serious microplastic pollution, equivalent to seriously polluting more than 54,800 Olympic-size saltwater swimming pools each year, researchers from the City University of Hong Kong (CityU) have found. . It can also affect the growth and reproduction of marine organisms and the food chain. The research team urged the public to properly dispose of their used masks and stressed the importance of better environmental management, formulating policies and corresponding enforcement to ensure proper disposal. surgical masks.

The research team was led by Dr. Henry He Yuhe, an assistant professor at CityU’s School of Energy and Environment (SEE) and a member of the State Key Laboratory of Marine Pollution (SKLMP). The results were published in the academic journal Letters on environmental sciences and technologies, titled “Release of microplastics from discarded surgical masks and their adverse effects on the marine copepod Tigriopus japonicus”.

Plastic material widely used in surgical masks

The research team cited an estimate from a US environmental organization that global demand for surgical masks will reach 129 billion per month by 2020. And some research has estimated that due to the Without proper collection and management policies, 1.56 billion masks have been improperly discarded globally. ocean in 2020.

“Polypropylene (PP) is the main material widely used in surgical masks. It is a kind of basic plastic that can break down under the effects of heat, wind, ultraviolet rays and ocean currents, eventually forming microplastics,” said Dr He. . Microplastics are typically less than five millimeters in size and can take hundreds of years to degrade in the ocean.

A walk with his dog on a beach sparked Dr. He’s interest in conducting the research. “I saw a mask stuck between rocks on the shore and another floating on the surface of the water. Since all masks are plastic and can release microplastics, improperly discarded masks will affect the marine environment. I think this problem will persist for many years into the post-pandemic era,” Dr. He said.

Une étude montre que les masques chirurgicaux jetés de manière inappropriée menacent l'écosystème marin et la chaîne alimentaire

The team collected the discarded masks and soaked them in seawater for nine days. The green bars in the graph show the amount of microplastics released and the orange bars are the data from the control experiment. Credit: Environmental Science and Technology Letters, DOI: 10.1021/acs.estlett.1c00748

To understand the scope and scale of this pollution problem and its potential impact, Dr. He and his team collected discarded masks on a Hong Kong beach to investigate the release of microplastics from polypropylene surgical masks in the ‘sea water.

Polluted seawater can fill more than 54,800 swimming pools a year

The team conducted lab experiments to mimic the natural process of releasing microplastics from discarded masks. They soaked the masks in a bottle of artificial seawater and continuously shook them using a mechanical shaker for nine days. Under the microscope, they observed significant damage to the fibers of the mask.

After analysis, the team found that a mask weighing around three grams released around 3,000 microplastics. They estimated that 0.88 million to 1.17 million microplastics would be released when a mask completely breaks down.

Given that approximately 1.56 billion masks ended up in the ocean in 2020, the team estimated that more than 1,370 trillion microplastics were released into the coastal marine environment from all surgical masks. discarded inappropriately during the year. “This amount of microplastics can seriously pollute 137 million cubic meters of seawater, which is equivalent to filling more than 54,800 Olympic swimming pools,” Dr He added.

Une étude montre que les masques chirurgicaux jetés de manière inappropriée menacent l'écosystème marin et la chaîne alimentaire

The top image shows fluorescently dyed microplastics in the intestines of copepods after exposure. The bottom image shows a copepod that was not exposed to microplastics, with no microplastics in the gut. Credit: Environmental Science and Technology Letters, DOI: 10.1021/acs.estlett.1c00748

Microplastics accumulate in the food chain

The team also assessed the chronic toxicity of microplastics on copepods (Tigriopus japonicus), a small marine crustacean. In their experiment, the copepods were exposed to artificial seawater containing up to 100 microplastics per ml. Microplastics have been ingested and accumulated in the intestines of marine copepods. Compared to copepods unexposed to microplastics, the reproductive fecundity of those exposed to 100 microplastics per ml was reduced by up to 22% and the developmental time to maturation was 5.6% longer.

Dr. He explained that as one of the most abundant classes of zooplankton and the primary food source for other small animals in the marine environment, copepods play a critical role in the bioaccumulation of contaminants in the web. food. Microplastics can enter the bodies of higher-level marine organisms, such as fish and shrimp, if they consume copepods with microplastics accumulated in their bodies. The higher up the food chain animals are, the more microplastics accumulate, leading to potentially harmful effects.

In addition, the reduced fecundity of copepods can lead to a decrease in the food resources of higher marine organisms, threatening the balance of the marine ecosystem.

Dr. He pointed out that microplastics released by masks can also act as carriers of other pollutants, such as plasticizers, in the marine environment and could have a cumulative effect on marine organisms.

The team believes that the results of their research provide significant evidence that the improper disposal of surgical masks can have a long-term domino effect on coastal marine ecosystems, which requires more attention and further study. To minimize the risk of this emerging threat, better environmental management, policies, and enforcement are needed to ensure proper disposal of surgical masks. The research team urges everyone to properly dispose of used masks to prevent microplastic pollution in the marine ecosystem.

Scientists warn that microplastic pollution of the oceans could be higher than expected

More information:
Jiaji Sun et al, Release of microplastics from discarded surgical masks and their adverse effects on the marine copepod Tigriopus japonicus, Environmental Science and Technology Letters (2021). DOI: 10.1021/acs.estlett.1c00748

Provided by City University of Hong Kong

Quote: Improperly Discarded Surgical Masks Threaten Marine Ecosystem and Food Chain (February 8, 2022) Retrieved February 17, 2022 from threaten.html

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