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Salt marshes trap microplastics in sediments, creating a record of human plastic use

Microplastics taken from sediment core samples in the Childs River region of Waquoit Bay, Massachusetts. Magnification 0.38 times. Credits: Miriam Ritchi

Plastic is everywhere. From mobile phones to pens, cars and medical devices, the modern world is full of plastics and plastic waste. A new study by scientists at the Marine Biological Research Institute (MBL) Ecosystem Center found that some of that plastic waste has accumulated in salt marshes for decades.The study was published in Environmental progress.


Salt marshes are links between land and open ocean ecosystems, in a sense connecting the urban environment with the wild sea. Microplastic (Plastic particles Tends to float (less than 5 mm). Water surface, But Salt marsh Filled with tides and emptied, floating particles are usually trapped in branches and roots and settle in wetland soil.

Sediments accumulate in salt marshes layer by layer, like annual rings, and maintain a historical record of sedimentation within the ecosystem. “By accumulating sediments, they keep records,” said Javier Loretto, a research scientist at MBL and co-lead author of the treatise.

Globally, scientists estimate that about 8 million tonnes of plastic flow into the ocean each year. However, until now, the amount of plastic trapped in the salt marsh ecosystem has not been estimated.

Researchers have taken core samples of marsh sediments at six different estuaries of the Waquoit Bay system in Cape Cod and at the port of New Bedford, Massachusetts, in a very contrasting area of ​​microplastics decades ago. I was able to track the abundance of. Degree of land use.

Salt marshes trap microplastics in sediments, creating a record of human plastic use

Claire McGuire, who obtains sediment core samples from Waquoit Bay in Falmouth, Massachusetts, was a student of the Environmental Sciences Semester Program at the Institute of Marine Biological Sciences, and this paper was born. Credits: Environmental Science Semester (SES) / MBL

“Going back in time, the amount of microplastics found is clearly declining,” says Ryolate. “The amount of microplastic found in the sediment is related to the number of people … but also the amount of plastic people use.”

“Waquoit Bay is the perfect salt marsh system for studying plastic pollution, because it allows us to compare areas that are barely touched with areas that are heavily influenced by human activity,” MBL’s research science says. It can be compared to other areas that are people and are strongly influenced by human activities. Co-lead author of the treatise. “We have found widespread plastic pollution.”

Researchers have focused on two types of microplastic contamination: debris (due to the decomposition of large pieces of plastic) and fibers (plastic like threads that easily fall off clothes and fishing tackle). They found that fragmentary pollution increased over time and with urbanization. The larger the population around the collection site, the more plastic Fragments observed by researchers.

One surprise of the data is that the concentration of microplastics in sediments was not linear as urbanization progressed. Until the development of 50%, the concentration of microplastic debris remained relatively unchanged, but when the land was occupied by 50%, the number of microplastics increased exponentially.

“A few people living in the surrounding area aren’t going to make a big difference, but when urban use occupies more than 50% of the country, the number of microplastics grows tremendously,” says Lloret.

Salt marshes trap microplastics in sediments, creating a record of human plastic use

Sediment core containing plastic debris from salt marshes in New Bedford, Massachusetts.Credit: Miriam Ritchie

Microplastic fibers were not in the same relationship as urbanization. “Even in less urbanized, more pristine areas, we find textiles. Plastic pollutionSays Pedrosa Pami.

Researchers believe that the origin of the debris is local (people who use or dispose of plastic where they live), but textiles are transported over long distances by air or water from large urban areas. May be done.

“When we started, we didn’t know if microplastics were a problem here in Cape Cod. Until now, no one has analyzed microplastics in Cape Cod’s wetland sediments,” says Ryolate. I will.

As scientists have shown Microplastic The next step in polluting New England salt marshes is to gain further insights. How do those particles reach the ecosystem? What is the source? How do they affect the ecosystems and food webs of the organisms that live there?

“There are still many open questions,” says Pedrosa-Pàmies. “This is also the first step in management.”


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For more information:
Javier Loreto and other salt marsh deposits act as microplastic sinks, revealing the impact of current and past land-use changes. Environmental progress (2021). DOI: 10.1016 / j.envadv.2021.100060

Quote: Salt marshes trap microplastics in sediments, creating a record of human plastic use (June 4, 2021) and on June 4, 2021 https://phys.org/news/2021 Obtained from -06-salt-marshes-microplastics-sediments-human. html

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Salt marshes trap microplastics in sediments, creating a record of human plastic use

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