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UM study finds microplastic pollution in Flathead Lake


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They are in our oceans and rivers. They are in the food we eat and the water we drink. They have even been detected in the human body. They are called microplastics – particles of plastic that are so small that they cannot be seen with the naked eye. Although researchers have known for years that these microplastics exist in Flathead Lake, the concentrations and origin of the microplastic pollution have remained a mystery.

Thanks to a study at the University of Montana’s Flathead Lake Biological Station, scientists now have a better understanding of the amount of microplastics contaminating Flathead Lake, the likely sources of these microplastics, and what can be done to prevent more from making their way. at Flathead Lake. the world famous pristine waters of the lake.

Recently published in the scientific journal Environmental pollution, this microplastics research was led by FLBS visiting researcher Dr. Xiong Xiong of the Institute of Hydrobiology of the Chinese Academy of Sciences. Xiong came to FLBS in 2018 with a mission to learn about microplastics in freshwater lakes in relatively unpopulated regions and provide insights to aid in their management.

“It looks pretty clean, but if this clean lake is suffering from plastic, I want to check that,” Xiong said at the start of his research four years ago. “I think people think that (plastic pollution) is more serious in the ocean, but a lot of people live inland and we need fresh water. It can affect our daily lives more directly than the plastic in the ocean.”

To conduct this study, Xiong joined FLBS Director Jim Elser and a team of scientists from biological stations to sample surface waters at 12 different locations around Flathead Lake over a one-year period. They then examined the samples for the occurrence, distribution and types of microplastics.

After analyzing the samples, the team found that while the levels of microplastic pollution measured in Flathead Lake were lower than in lakes in densely populated areas, Flathead had microplastic levels comparable to or higher than the lakes studied in other, less densely populated areas. densely populated areas of the world.

In other words, Flathead Lake is now home to microplastics and new microplastic particles are added every day.

“Microplastics in lakes can disrupt food webs because animals like zooplankton and fish can ingest them,” Elser said. “They can introduce toxins into the animal, displace real food and physically damage the digestive tissues.”

According to the study, there are three ways microplastics reach Flathead Lake. One way is atmospheric microplastic deposition. This occurs when microplastics are transported through the atmosphere (e.g. wind and clouds) to Montana from other more populated areas and then fall into Flathead Lake, either directly from the air (known as dry deposition) or through snow and rainfall (wet deposition). ).

Microplastics in dry deposition were highest in the fall season, while wet deposition was highest in the winter season.

“This study showed that microplastics literally rain down on us — and snow,” said Elser.

The other two other ways microplastics can enter Flathead Lake are through the lake’s major river entrances, including the Flathead River on the north side of the lake and lake sources near larger coastal communities such as Polson, Bigfork, and Lakeside.

At the mouth of the Flathead River, probably the largest source of microplastics comes from the disposal of plastic waste, which in Flathead County is primarily landfilled rather than recycled. While landfills in the Flathead Watershed are not open pits, microplastics are mobilized through leachate (water that picks up contaminants) and through the landfill’s soil when wind carries dust away.

Meanwhile, in the more densely populated coastal areas of the lake, researchers found that concentrations of microplastics were particularly high. In addition to plastic packaging, much of today’s clothing is made from fibrous plastic. These synthetics decompose at a microscopic level during washing and are then transported and deposited in our waters through septic sewage fields and communal water treatment plants.

Plastic waste from other human activities also deserves attention. A variety of water activities such as kayaking, sailing, speed boating, water skiing and fishing are prime outdoor pursuits at the Flathead Watershed. But these activities include plastic boats, ropes, floats and fishing lines that can degrade over time and turn into microplastics.

While the levels of microplastics in Flathead Lake are relatively low, they are a cause for concern. However, researchers are quick to point out that much can be done to reduce their presence in Montana’s waters.

“While we need to know more about the impact of microplastics in our lakes, we know enough to take action now to reduce plastic inputs,” Elser said. “Each of us can reduce our use of plastic, dispose of it appropriately and implement impactful approaches such as washing filters. We can also encourage companies to do the same and for governments to provide facilities and systems to better handle plastic. in our catchment area.”

Fibrous microplastics can be reduced by improving laundry practices and wastewater treatment or by reducing the use of synthetic fiber materials in favor of clothing and natural fiber materials. For example, a recent study in California found that using in-line filters in washing machines had the potential to reduce annual emissions of synthetic microfibers to natural environments by nearly 80%.

Further strengthening plastic waste disposal measures by both residents and visitors could greatly help reduce microplastic pollution in Flathead Lake. Such measures include better education about the harms of improper disposal of plastic, improving the recycling of plastic waste in the region, and reducing the overall use of plastic products, such as single-use plastics common in the hospitality industry.

When it comes to reducing atmospheric microplastic deposition, researchers said comprehensive solutions are needed. The total production of plastic waste in the United States is 42 million tons per year, which is much higher than in other countries per capita. This suggests that, even in an area with a relatively low population, Flathead Lake continues to be at risk from airborne microplastics until nationwide action can be taken.

Xiong and his research team said more studies are needed to better understand and address our microplastic problem, not just in the Flathead Watershed but around the world. The good news is that because human activities are undeniably the only source of microplastics, this is a problem we can solve.

Microplastics threaten typical remote cryospheric areas

More information:
Xiong Xiong et al, Microplastics in Flathead Lake, a large oligotrophic mountain lake in the US, Environmental pollution (2022). DOI: 10.116/j.envpol.2022.119445

Provided by the University of Montana

Quote: UM study finds microplastic pollution in Flathead Lake (2022, June 23) retrieved June 23, 2022 from https://phys.org/news/2022-06-um-microplastic-pollution-flathead-lake.html

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