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Scientists discover enormous reserves of mercury in permafrost

ANI  |  Washington D.C. [USA] 

Scientists have discovered massive reserves of hidden in

is a thick subsurface layer of soil that remains below freezing point throughout the year, occurring chiefly in polar regions.

Researchers have discovered in the northern hemisphere stores massive amounts of natural mercury, a finding with significant implications for human health and ecosystems worldwide as exposure to - even small amounts - can cause serious health problems.

The study reveals the northern soils are the largest reservoir of on the planet, storing nearly twice as much as all other soils, the ocean and the atmosphere combined.

In a new study, scientists measured concentrations in cores from and estimated how much has been trapped in north of the equator since the last Ice Age.

"This discovery is a game-changer," said Paul Schuster, a at the U. S. Geological Survey in Boulder, and of the new study. "We've quantified a pool of that had not been done previously, and the results have profound implications for better understanding the global cycle."

Warmer air temperatures due to climate change could thaw much of the existing layer in the northern hemisphere. This thawing could release a large amount of that could potentially affect ecosystems around the world. accumulates in aquatic and terrestrial food chains, and has harmful neurological and reproductive effects on animals.

"There would be no environmental problem if everything remained frozen, but we know the Earth is getting warmer," Schuster said. "Although measurement of the rate of thaw was not part of this study, the thawing provides a potential for to be released--that's just physics."

The new findings have major implications for understanding how Earth stores and for human and environmental health, according to James Shanley, a at the U. S. Geological Survey in Montpelier, Vermont, who was not involved with the new research.

"This study is very novel and makes a big discovery in an area that was previously somewhat ignored," Shanley said. "It shows represents a huge source of mercury, and if it thaws due to climate change the could be released and could significantly add to the global burden."

Natural found in the atmosphere binds with organic material in the soil, gets buried by sediment, and becomes frozen into permafrost, where it remains trapped for thousands of years unless liberated by changes such as thaw.

Schuster's team determined the total amount of locked up in using field data.

Between 2004 and 2012, the study authors drilled 13 soil cores from various sites in Alaska, and measured the total amounts of and carbon in each core. They selected sites with a diverse array of soil characteristics to best represent found around the entire northern hemisphere.

Schuster and his colleagues found their measurements were consistent with published data on in non-and soils from thousands of other sites worldwide. They then used their observed values to calculate the total amount of stored in in the northern hemisphere and create a map of concentrations in the region.

The study found approximately 793 gigagrams, or more than 15 million gallons, of is frozen in northern soil. That is roughly 10 times the amount of all human-caused emissions over the last 30 years, based on emissions estimates from 2016.

The study also found all frozen and unfrozen soil in northern regions contains a combined 1,656 gigagrams of mercury, making it the largest known reservoir of on the planet. This pool houses nearly twice as much as soils outside of the northern region, the ocean and the atmosphere combined.

Scientists are still unsure how much of the stored would affect ecosystems if the were to thaw. One major question revolves around how much of the would leach out of the soil into surrounding waterways, according to Steve Sebestyen, a at the USDA Forest Service in Grand Rapids, Minnesota, who was not involved with the new research.

If the is transported across waterways, it could be taken up by microorganisms and transformed into methylmercury, he said. This form of is a dangerous toxin that causes neurological effects in animals ranging from motor impairment to birth defects.

"There's a significant social and human health aspect to this study," Sebestyen said. "The consequences of this being released into the environment are potentially huge because has health effects on organisms and can travel up the food chain, adversely affecting native and other communities."

Edda Mutter, director for the Yukon River Inter-Tribal Watershed Council, said the new study demonstrates thawing could have grave consequences for local ecosystems and indigenous communities in the northern hemisphere.

"Rural communities in and other northern areas have a subsistence lifestyle, making them vulnerable to methylmercury contaminating their food supply," Mutter said. "Food sources are important to the spiritual and cultural health of the natives, so this study has major health and economic implications for this region of the world."

The release of could also have far-reaching global consequences, according to Shanley. released into the atmosphere can travel large distances and could affect communities and ecosystems thousands of miles away from the release site, he said.

Schuster believes his team's research gives policymakers and scientists new numbers to work with and calibrate their models as they begin to study this new phenomenon in more detail.

"24 percent of all the soil above the equator is permafrost, and it has this huge pool of locked-up mercury," he said. "What happens if the thaws? How far will the travel up the These are big-picture questions that we need to answer."

The new study was published in Geophysical Research Letters, a journal of the

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)

First Published: Tue, February 06 2018. 11:25 IST