A team of researchers investigated how stream content and flow affect microplastic retention.
These small plastic particles found in everyday products ranging from face washes to toothpaste are new threats to health and ecology, urging teams to identify what affects microplastic retention in river ecosystems.
Daily actions such as synthetic clothing and driving that wear tires contribute to the accumulation of microplastics in urban dust to waterway environments. These plastics often carry toxic chemicals that can threaten the health of humans and wildlife.
“We are an important source of microplastics,” says Shannon Speyer, an assistant professor and researcher at Dale Bumpers College of Agriculture, University of Food Science and the Arkansas Agricultural Experimental Bureau.
The study explains that microplastic retention in streams is a concern because they are ingested by aquatic organisms, poses a threat to digestion and fertility, and everything is easily spreading.
How microplastic structures affect movement
Microplastics are unique in size, construction and weight. They can turn and be rounded in under 5 mm, as seen in some face washes and toothpastes. Or it could be a string-like fiber like small particles that can be removed while washing synthetic clothing materials such as polyester or nylon.
Ultimately, these microplastics could end up in rivers and oceans.
These different sizes and shapes make microplastics more complicated and encourage researchers to look into which factors are trapped in the stream.
Specific areas of microplastic retention and removal
The team designed the experiment by side-by-side boards made of four artificial flows made from cobblestone, pea gravel, sand, and three mixtures.
They then colonized the river with benthic algae, or algae that live on the surface of the bed, and experimentally released microplastics over three days to test microplastic retention when substrate, discharge levels and presence of algae change.
The team found that streams with higher levels of algae, larger river substrates, and higher levels of river discharge all increased levels of microplastic retention during the 3-day experimental period of the study.
The findings also reveal that microplastics could be resuspended in cases of rapid increases in emissions, such as storms. That is, they are lifted from the bottom of the calm stream.
These events increase the likelihood that these particles will be transported downstream.
John Kelly, professor and director of biology at Loyola University Chicago and corresponding author of the study, explained: “The results of this study show that, for example, the characteristics of a particular river, such as rocky bottoms compared to the bottom of a sandy river, can determine where microclastic particles accumulate within the river.
“These results can be used to determine where to prioritize cleanup efforts.”
He added: “Our results show that storms can lead to microplastic movements from the bottom of the river to the water. This can be used to determine the best timing for removing microplastics from streams.”
Group action is essential
Speir explained the everyday ways that individuals can fight microplastic deposition and stream ecosystems, and warned them not to think that these singular behaviors would not have an impact.
She cited the use of laundry bags designed to catch microplastics washed out of clothes when washed.
She concluded:
“We need to keep it in mind whenever we think about our individual behavior, our environment.
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