Legacy levels can persist for decades
From: Allison Winter, ENN.com
Most of us are aware of the high levels of mercury found in fish. But where does this mercury come from?
Humans have been using
mercury since before the Industrial Revolution, but it is currently being
emitted by coal-fired power plants and artisanal gold mining. EDITOR’S
NOTE: also from garbage incinerators. There are several in Connecticut just
upwind from Charlestown. RIDEM has issuing warnings about consumption of
freshwater fish in RI waters since 1986 due to mercury contamination. For
example, they warn that no one should eat more than one meal with fish catch in
Watchaug Pond. Click
here for their 2013 guidebook.
Mercury particles then
end up getting released into the air which end up raining down into water
bodies and absorbed into the soil. Eventually these microbes in aquatic
ecosystems convert mercury into methylmercury which accumulated in fish and
consequently can cause health effects for those who consume these fish
products.
"It's easier said
than done, but we're advocating for aggressive reductions, and sooner rather
than later," says Helen Amos, a Ph.D. candidate in Earth and Planetary
Sciences at the Harvard Graduate School of Arts and Sciences and lead author of
the study, published in the journal Global Biogeochemical Cycles.
Their model reveals that
most of the mercury emitted to the environment ends up in the ocean within a
few decades and remains there for centuries to millennia.
While mercury is
naturally released during volcanic eruptions, humans are the main culprit to
the pollution.
"Ideally, mercury
released by human activities would quickly be sequestered in the environment,
but instead what we see is a huge quantity of it bouncing from one reservoir to
the next," explains senior author Elsie M. Sunderland, who is the Mark
& Catherine Winkler Assistant Professor of Aquatic Science at the Harvard
School of Public Health.
"This means it continues cycling throughout the
environment and persists for much longer timescales than most people realize,
which has implications for long-term biological exposures."
"Today, more than
half of mercury emissions come from Asia, but historically the U.S. and Europe were
major emitters," says second senior author Daniel J. Jacob, Vasco McCoy
Family Professor of Atmospheric Chemistry and Environmental Engineering at
Harvard SEAS. "We find that half of mercury pollution in the present
surface ocean comes from emissions prior to 1950, and as a result the
contribution from the U.S. and Europe is comparable to that from Asia."
Sunderland notes:
"Our study reinforces the need for immediate and stringent emissions
controls globally, to the extent technologically possible, to avoid future
human health risks. Already, the costs of methylmercury exposure in Europe and
the United States have been estimated at upwards of $15 billion."
Read more at Harvard University.
