Recently, scientists discovered huge reserves of natural mercury hidden under thawing permafrost in the Northern Hemisphere. The study was published in Geophysical Research Letters, a journal of the American Geophysical Union. The finding has a significant impact on human health and ecosystem globally.
It was found that nearly 793 gigagrams or more than 15 million gallons of mercury is frozen in northern permafrost soil. The study reveals that the northern permafrost regions are the largest reservoir of mercury on earth, storing about twice as much mercury as all other soils, the ocean, and the atmosphere.
“This implies permafrost regions contain roughly 10 times the total human mercury emissions over the last 30 years,” said Kevin Schaefer, NSIDC scientist, a co-author of the study.
He said that as long as the permafrost remains frozen, the mercury will stay trapped in the soil. Higher air temperatures because of climate change could melt much of the permafrost, releasing mercury that could gravely affect earth’s ecosystems. The released mercury can get collected in aquatic and terrestrial food chains, causing devastating neurological and reproductive effects on animals.
The study also found that all the frozen and unfrozen soil in northern permafrost regions contains 1,656 gigagrams of mercury. This makes the region the largest known reservoir of mercury on the earth.
Scientists are doubtful about what quantity of mercury would affect ecosystems if the permafrost melted. Steve Sebestyen, a research hydrologist at the USDA Forest Service in Grand Rapids, Minnesota, who was not involved in the study said that one vital question is that what amount of the mercury would leach out of the soil into the waterways nearby. He said that if the mercury is carried across waterways, it could be taken up by microorganisms and converted into methylmercury, a dangerous toxin that causes neurological effects in animals.
Sebestyen said that the consequence of the mercury being released into the atmosphere is potentially great as mercury has health effects on organisms. It can reach the food chain, thereby adversely affecting native and other communities.
Edda Mutter, science director for the Yukon River Inter-Tribal Watershed Council said that the finding shows thawing permafrost could have serious consequences on local ecosystems and indigenous communities in the northern hemisphere.
He also said that the rural communities in Alaska and other northern regions were more vulnerable to methylmercury contaminating their food supply due to their subsistence lifestyle.
The researchers determined the total amount of mercury trapped under permafrost using field measurements. In the period from 2004 and 2012, the study authors drilled 13 permafrost soil cores at different sites in Alaska and measured the quality of mercury and carbon in each core.
Schaefer and his colleagues found that their measurements were consistent with published data on mercury in non-permafrost and permafrost cores from several other sites. Making use of the observed values, they calculated the total mercury stored in permafrost in the Northern Hemisphere and created a map of soil mercury concentrations in the region.
According to the researchers, their study offers policymakers and scientists new numbers to work with and calibrate their models as they begin to study this new finding more elaborately.