Mercury concentrations in Yukon river fish could surpass EPA criterion
by 2050

Date:
September 16, 2020
Source:
NASA/Goddard Space Flight Center
Summary:
The concentration of mercury in the fish in Alaska's Yukon River
may exceed the EPA's human health criterion by 2050 if greenhouse
gas emissions that cause global warming are not constrained,
according to new research.



FULL STORY ==========================================================================
The concentration of mercury in the fish in Alaska's Yukon River may
exceed the EPA's human health criterion by 2050 if greenhouse gas
emissions that cause global warming are not constrained, according
to scientific research funded in part by NASA. This first of its kind
research estimates potential releases of mercury from thawing permafrost
under high and low carbon emissions scenarios.

The researchers predict that by 2200, the mercury emitted into both the atmosphere and water annually by thawing permafrost will compare with
current global anthropogenic mercury emissions. That's because higher
carbon emissions lead to faster and more atmosphere and water, where it
can accumulate in wildlife like fish.


==========================================================================
The team's results were published Sept. 16 in Nature Communications.

"If we can hit the Paris Accord target, we expect minimal impacts
to mercury concentrations in fish and water. If we continue with
unconstrained greenhouse gas emissions, however, it is likely that we
will see large increases in mercury concentrations," said Kevin Schaefer,
a scientist at the National Snow and Ice Data Center (NSIDC) and lead researcher on the project. Mercury emissions of these magnitudes could
have a global impact. "What happens in the Arctic does not stay in the
Arctic," said Schaefer, "The mercury emissions from thawing permafrost
could persist for centuries, impacting the environment both locally and globally." In 2018, Schaefer and several of his colleagues found that permafrost soils store nearly twice as much mercury as all other soils,
the ocean and the atmosphere combined. That work was funded by NASA
as part of the Arctic-Boreal Vulnerability Experiment (ABoVE), a major
effort to improve understanding of how climate change is affecting Arctic ecosystems, and how those changes ultimately affect people and places
in the Arctic and beyond. Now, the researchers have created a model
-- which relies in part on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Terra satellite --
to predict how mercury emissions from thawing Arctic permafrost will
change under different global emissions scenarios.

The new paper characterizes the release of mercury from thawing permafrost
for high and low carbon emissions scenarios based on two of the four Representative Concentration Pathways (RCPs) from the Intergovernmental
Panel on Climate Change's Fifth Assessment Report (AR5). The high carbon emissions scenario (RCP 8.5) assumes unconstrained "business as usual" emissions, while the low carbon emissions scenario (RCP 4.5) assumes
carbon emissions consistent with the Paris Agreement global target of
less than 2 degrees Celsius of warming above pre- industrial levels.

The results indicate minimal impacts to mercury concentrations in water
and fish for the low carbon emissions scenario and large increases for
the high carbon emissions scenario. At the global level, the high carbon emissions scenario would significantly increase the amount of mercury
released into the atmosphere, where it would persist in the environment
for centuries. At a local level, this would result in large increases
to mercury concentrations in fish and water in the Yukon River. For the
high emissions scenario, mercury concentrations could double in the Yukon
River by 2100. The low carbon emissions scenario shows minimal mercury
releases to the atmosphere and small changes to mercury concentrations in
fish and water. For the low emissions scenario, mercury concentrations
would likely increase by only about 14 percent and would not exceed EPA criterion by 2300.

"The thaw of permafrost due to climate change may release mercury as
well as greenhouse gases like methane. We need to comply with the Paris
Accord target of 2 degrees C. Otherwise, under a high emission scenario, a significant portion of mercury will be released to the environment, and it
will continue for hundreds of years," said Yasin Elshorbany, a co-author
on the study from the University of South Florida St. Petersburg campus.

The Yukon River is the fifth largest drainage basin in North America
and home to one of the world's longest salmon runs. It serves as an
important commercial and subsistence fishery.


========================================================================== Story Source: Materials provided by
NASA/Goddard_Space_Flight_Center. Original written by Sofie Bates,
NASA's Goddard Space Flight Center; and Audrey Payne, National Snow and
Ice Data Center. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Kevin Schaefer, Yasin Elshorbany, Elchin Jafarov, Paul F. Schuster,
Robert G. Striegl, Kimberly P. Wickland, Elsie
M. Sunderland. Potential impacts of mercury released from
thawing permafrost. Nature Communications, 2020; 11 (1) DOI:
10.1038/s41467-020-18398-5 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200916113409.htm

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