Microplastics in Groundwater (and Our Drinking Water) Present Unknown
Risk
Boulder, Colo., USA: Microplastics (plastics <5mm) and their negative
health impacts have been studied in oceans, rivers, and even soils, and
scientists are beginning to grapple with the myriad human health impacts
their presence might have. One understudied, but critical, link in the
cycle is groundwater, which is often a source of drinking water.
While microplastics in groundwater likely affect human health, only a
handful of studies have examined the abundance and movement of
microplastics in groundwater. This gap means the potential for adverse
health effects remains largely unknown.
At the Geological Society of America’s 2020 Annual Meeting today at 1:30,
Teresa Baraza Piazuelo, a Ph.D. candidate at Saint Louis University, will
help fill that knowledge gap by presenting new research on groundwater
microplastics in a karst aquifer. “There hasn’t been that much research
looking at [micro]plastics and groundwater,” Baraza says. “It’s a very new
topic. There’s been a boom of research on microplastics in the ocean, even
in soils… but to fully understand something, you have to explore it in all
its aspects.”
Microplastics pose multiple physical and chemical risks to the ecosystems
where they’re present, and those risks are exacerbated by plastics’
longevity in natural environments. “Since they’re plastic, they’re very
durable,” Baraza says, “which is why plastic is great. But it doesn’t
degrade easily.” Microplastics’ ability to linger in their environments for
decades or longer likely has cumulative detrimental effects on both the
organisms and quality of the ecosystem. Their chemical threat stems largely
from their ability to transport harmful compounds on their surfaces; when
organisms at the base of the food chain ingest microplastics, they ingest
the toxins, too. As larger organisms consume the smaller ones, the toxins
can build up (a process called bioaccumulation), eventually resulting in
responses like organ dysfunction, genetic mutation, or death. “Cave
ecosystems are known for being super fragile to begin with,” she explains.
“All the cave organisms — salamanders, blind fish — are sensitive, so any
contaminants that are introduced could damage those ecosystems.”
Groundwater can stay in the same aquifer for tens to hundreds of years, or
even longer. Combining that long residence time with plastics’ resistance
to degradation means that those chemical effects could effectively build up
in the water and in any organisms within it, increasing the likelihood of
toxic bioaccumulation. Together, these could result in long-term
contamination of water sources with poorly-understood health effects and
ecosystem damage.
To understand where microplastics in groundwater come from and how they
move through aquifers, Baraza and her Ph.D. advisor have been sampling
groundwater from a Missouri cave weekly, all year long, and analyzing its
chemistry and microplastics load. Because previous
groundwater-microplastics studies have been limited to low-rainfall
conditions, they’re also studying how flooding events affect microplastics
concentrations in groundwater.
So far, they’ve found that while microplastics do increase in groundwater
during a flood event, there’s also a second peak in microplastics after the
flooding has begun to wane. Their explanation is that there are two sources
of microplastics for groundwater: those that are already in the subsurface,
and those that are newly delivered from the surface. “Finding so much
plastic later on in the flood, thinking that it could be coming from the
surface… is important to understand the sourcing of microplastics in the
groundwater,” Baraza says. “Knowing where the plastic is coming from could
help mitigate future contamination.”
Their current flood results are only based on one event, but Baraza will
continue sampling through the rest of the year — weather permitting. “Flood
sampling is hard,” she says, “especially in St. Louis, where the weather is
so unpredictable. Sometimes we think it’s going to rain and then it doesn’t
rain, and then sometimes it doesn’t seem like it’s going to rain, but it
does… we caught a flood a week ago, and we are expecting to catch a couple
more floods.” The effort is worth it to determine if flooding events —
which are becoming more common under climate change — are highly-effective
deliverers of microplastics in groundwater reservoirs.
Session no. 23 – T191. New frontiers in cave and karst research I
Monday, 26 Oct.: 1:30 to 5:30 p.m. EDT
Presentation time: 1:30 to 1:45 p.m. EDT
Session Link:
https://gsa.confex.com/gsa/2020AM/meetingapp.cgi/Session/50065
Paper 23-1:
Quantifying microplastic debris sourcing and transport for a karst
aquifer
Abstract Link:
https://gsa.confex.com/gsa/2020AM/meetingapp.cgi/Paper/355066
Contact
: Teresa Baraza Piazuelo, Saint Louis University, Missouri;
teresa.barazapiazuelo@slu.edu.
The Geological Society of America, founded in 1888, is a scientific society
with over 20,000 members from academia, government, and industry in more
than 100 countries. Through its meetings, publications, and programs, GSA
enhances the professional growth of its members and promotes the
geosciences in the service of humankind. Headquartered in Boulder,
Colorado, GSA encourages cooperative research among earth, life, planetary,
and social scientists, fosters public dialogue on geoscience issues, and
supports all levels of earth-science education.
https://www.geosociety.org
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