WeatherFanatics: Climate change may boost mercury in ecosystems, food chain

By Michael Kuhne, AccuWeather staff writer

February 27,2017, 11:03:00AM,EST

Rising temperatures may cause localized increases in the amount of toxic mercury introduced into ecosystems, impacting wildlife and the food chain.
According to a recent study published in Science Advances, mercury in ecosystems has risen two- to five-fold since the dawn of the industrial age. Today, climate change may be causing an even greater problem for some areas as an increase in organic matter enters waterways.
"Increased temperature may regionally cause increases in precipitation and runoff, and if so, in export of organic matter from land to water," the study's author and environmental chemist Erik Björn said.
This relation is complex and projected to vary highly for different geographical regions, he added.

Björn, and his fellow researchers, used the mesocosm research infrastructure at the Umeå Marine Science Centre in Sweden to construct different model ecosystems. This system consisted of 12 plastic tubes measuring at 75 centimeters in diameter and 5 meters high.
Each tube was filled with 2,000 liters of water and a sediment at the bottom. This allowed the researchers to control temperature, light conditions and the addition of nutrients and organic matter to form different types of model ecosystems.
"We combined this approach by the addition of isotopically enriched mercury tracers. We added three tracers to the sediment and two to the water phase to simulate different pools of mercury in the ecosystem," he said. "We then monitored throughout the experiment how methylmercury was formed and accumulated in biota for these different isotope tracers."
Because of the increases in natural organic matter from the soil, water becomes more brownish in color. This decreases the amount of sunlight that can penetrate, causing a decrease in photosynthetic production of the photoplankton.
Instead, bacteria that use part of the organic matter for their metabolism can then increase.
"This causes a change in the structure of the food web, from being dominated by phytoplankton to being dominated by bacteria," Björn said, adding that there are a larger number of steps in the bacteria-based food web compared to the phytoplankton-based food web.
Methylmercury is formed by certain types of microorganisms that use inorganic mercury located in soils, sediment and water. The inorganic mercury mainly originates from atmospheric depositions, both naturally and from emissions related to human activity.
A fraction of the toxic methylmercury will bind to sulfide and chloride, which can be then be available in the cellular uptake in bacteria and plankton, he added.
"Methylmercury has strong neurotoxic properties. Observed effects in wildlife like fish, birds and mammals, include behavioral, neurochemical, hormonal and reproductive changes," Björn said.
The impact of increased runoff on the aquatic ecosystem is due to increase precipitation among other things and is dependent on the watershed and water surface areas.
For example, in certain regions, temperature-driven increases in precipitation may be accompanied by increases in the evaporation of water from the soil and have only minor effects in runoff.
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"A larger watershed area to water surface area means a larger potential impact from land runoff, although several other factors also contribute," he added. "As a consequence, small boreal lakes and coastal regions are more impacted by runoff than the open oceans."
A further consequence of this is the establishment of a new type of “intermediate” predatory organisms like protozoa which feed on the bacteria.
"Methylmercury is enriched approximately by a factor of 10 in each step of the food web, and therefore the amount of methylmercury in zooplankton and higher predators increases in the bacteria-based food web," he added.
For predatory organisms, including humans, the main exposure route for methylmercury is through food consumption.
"In each step in the food chain, methylmercury gets concentrated approximately 10 times, which means that the concentrations increases throughout the food chain and is highest in top predators," Björn said.

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Like · Reply · 1 hr

Vicky Bruno

Well, with the new EPA Boss that Chump appointed, and all the regulations for the fossil fuel industries he wants to get rid of and start allowing big oil, big Coal and other industrial pollution Giants to run amock, all for the sake of their profits, we are only going to see the die off of more species, more toxic chemicals polluting our land, air and water, that mercury in fish will be the least of our worries in a few short years.

Like · Reply · 1 · 2 hrs

Michael Mootsey ·

Hogwarts School of Witchcraft and Wizardry (Official)

No one has ever seen God, or ever proven a fact about any faith,but somehow that is never questioned as bunk like climate change, deniers scoff at every study and won't believe the truth even when confirmed. We will never learn. Keep your heads in the sand.

Like · Reply · 1 · 2 hrs

Tony Berg ·

MANKATO TECHNICAL COLLEGE

A warming planet is not all bad news yet that's all we hear.

Like · Reply · 3 hrs

Dan McMartin ·

Standing in a river waving a stick at Trout bum

I went into the wrong line of work. I should have gotten into climate science. I could live on generous government grants, probably be tenured at some university and get a nice fat penion too. All for publishing a bunch of mights and what ifs that my collegues gush over, most people can't understand and nobody ever really verifies.

Like · Reply · 2 · 5 hrs

Ed Gleason ·

Sarasota High School

So, we're all going to die. Again. BTW, 2020 will be the golden anniversary of the earth ending in just ten years. RSVP now, and beat the rush!

Like · Reply · 5 hrs

Steve McGlamery ·

Queen Creek, Arizona

The sky is falling, the sky is falling.

Like · Reply · 1 · 5 hrs

Don Rehberg ·

Valdosta State University

Thanks for putting this on your WEATHER site. sarc/off

Like · Reply · 3 · 8 hrs

Michael Hawryluk

May cause, might cause, could cause... Yep, the science is settled.

Like · Reply · 4 · 8 hrs

Gary French

Amazing how no one was worried about this when the James Bay Project was introduced and implimented, flooding an area the size of France, making the waters so polluted with mercury from decaying trees, vegitation, people couldn't eat the fish. Migrating animals were drowning because their crossing lands were now flooded.

Like · Reply · 1 · 10 hrs

Renee Koenitzer

And the more people breed with no thought to the consequences, the more this will happen. Or, at least, breed and think they're all entitled to the same goodies as previous generations.

Like · Reply · 1 · 4 hrs