30 May/June 2022
Science
7COURTESYOCEAN^ WISE(FIBERS)Because of their minute size, microplastics
aren’t easy to track. For many years, researchers
assumed these tiny bits of trash entered rivers,
where they were carried downstream to the ocean
in a relatively short amount of time. But that’s not
actually the case. According to a new study pub-
lished in Science Advances, it’s estimated that
microplastics may remain in rivers for more than
300 years before entering the ocean. This means
the microplastics in rivers have much greater
potential to cause harm to humans and the envi-
ronment than scientists previously thought.
Microplastics enter rivers in a number of ways,
says Lisa Erdle, Ph.D., a microplastics expert and
the director of science and innovation for The 5
Gyres Institute, a U.S.-based nonprofit research
group focused on plastic pollution. For example,
tire particles and other roadway waste can wash
into rivers during a storm. In some cases, poorly
filtered plastic manufacturing waste is dumped
directly into a river. But researchers see one type
of microplastic more often than others, Erdle
says: microfibers, or threads shed by things like
upholstery and clothing. “We wear a lot of plas-
tic, especially fast fashion,” Erdle says, referring
to materials like polyester and nylon used to make
inexpensive clothing that often doesn’t hold up well
after a short time of regular wear or washing.
Experts have long assumed that once microplas-
tics entered a river, it would be only days or even
hours before they were dumped into the ocean.
But research from Jennifer Drummond, Ph.D., a
research fellow at the University of Birmingham
in the U.K., and her colleagues suggests there is
significant plastic retention in rivers. Because of tur-
bulence and water mixing beneath the surface, calledhyporheic exchange, microplastics don’t just f loat on
the surface or sink to the bottom. Instead, they move
dynamically down the river at a rate as slow as seven
years per kilometer (11.2 years per mile). Simply put,
“rivers aren’t pipes,” Drummond says.
Although these granules of waste aren’t likely
to plug up rivers or clog our intestines when con-
sumed, microplastics can still do harm. “Plastics
contain hundreds of different chemicals added
to them when they’re produced,” says Alice Hor-
ton, Ph.D., a research scientist and microplastics
expert at the National Oceanography Centre,
an oceanographic research institute based in
the U.K. Bacteria and viruses can also attach
to microplastics that may later be consumed by
humans and wildlife, says Drummond.
There are a handful of efforts to clean up river
plastic pollution, including Baltimore’s solar- and
hydro-powered Mr. Trash Wheel. Installed in 2014,
the semi-autonomous f loating machine funnels
trash into its “mouth” with two long booms, then
rakes the materials onto a conveyer-belt “tongue”
that drops the waste into a dumpster. While such
machines have collected several thousand tons of
trash debris that otherwise would have entered
the ocean—Mr. Trash Wheel has pulled more than
1,760 tons of trash out of Baltimore’s Inner Har-
bor—experts say that amount is barely scratching
the surface, partially because the majority of
microplastics pass right through their filters.
The only way to clean up microplastics, and
really all plastic, is to stop them from entering into
the environment in the first place, experts say. This
means using less plastic, coming up with better dis-
posal methods, and designing products that can be
more readily recycled and reused.FIGHTING FIBERS
Tiny threads from synthetic
clothing and textiles are
one of the most common
types of microplastics. In
addition to buying natural-
fiber clothing, here’s how
you can limit the amount of
microfibers you contribute
to the environment via your
washing machine.WASH LIKE
ITEMS TOGETHER
Washing items made
from similar materials
together keeps thread-
unraveling friction to
a minimum.GOING COLD
Washing in cold water
and using a shorter cycle
can extend the life of your
favorite pair of jeans and
limit microfiber shedding
by as much as 30 percent,
per a 2020 study. Swap-
ping out your dryer for a
clothesline helps, too.TRAP IT EARLY
There are several products
designed to prevent fibers
from entering waterways,
including tightly woven
mesh bags (Guppyfriend
has one for $35) that trap
threads, and specialized
filters for your washing
machine’s discharge hose.