{"id":10765,"date":"2017-12-17T04:45:14","date_gmt":"2017-12-17T04:45:14","guid":{"rendered":"http:\/\/www.lifeandnews.com\/articles\/?p=10765"},"modified":"2017-12-18T04:51:42","modified_gmt":"2017-12-18T04:51:42","slug":"mercury-from-industrialized-nations-is-polluting-the-arctic-heres-how-it-gets-there","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/mercury-from-industrialized-nations-is-polluting-the-arctic-heres-how-it-gets-there\/","title":{"rendered":"Mercury from industrialized nations is polluting the Arctic \u2013 here’s how it gets there"},"content":{"rendered":"

Daniel Obrist<\/a>, University of Massachusetts Lowell<\/a><\/em><\/span><\/p>\n

Scientists have long understood that the Arctic is affected by mercury pollution, but know less about how it happens. Remote, cold and seemingly pristine, why is such an idyllic landscape so contaminated with this highly toxic metal?<\/p>\n

I recently returned from a two-year research project in Alaska, where I led field research into this issue alongside fellow scientists from the University of Colorado<\/a>; the University of Nevada\u2019s Desert Research Institute<\/a>; the University of Toulouse<\/a> and the Sorbonne University<\/a> in France; and the Gas Technology Institute<\/a> in Illinois.<\/p>\n

Our work was the most comprehensive investigation to date of how mercury is deposited to the Arctic tundra, a vast northern ecosystem surrounding the Arctic Ocean. Our findings<\/a> show that the gaseous form of mercury \u2013 emitted by coal-burning, mining and other industrial processes in the industrialized world \u2013 is being lofted into the region from thousands of miles away. In the Arctic, it is deposited onto tundra soils and ultimately runs off into ocean waters, threatening the region\u2019s wildlife and people.<\/p>\n

Tracing mercury\u2019s pathways<\/h2>\n

Industrialized and developing nations emit about 2,000 tons of mercury into the atmosphere every year. Globally, the largest sources include emissions from small-scale and artisanal gold mining and coal-burning power plants. <\/p>\n

\n \"\"<\/a>
\n Mercury emissions from the eight highest emitting industry sectors. Data for 2010 from the 2013 UNEP Global Mercury Assessment. Total estimated global anthropogenic mercury emissions are 1960 metric tons.<\/span>
\n USEPA<\/a><\/span>
\n <\/figcaption><\/figure>\n

Mercury emissions from human activities take several forms that behave differently in the atmosphere Oxidized mercury, notated as Hg(II), generally settles or is rained out of the atmosphere close to emission sources. In contrast, gaseous elemental mercury, or Hg(0), remains in the atmosphere for a long time and can travel around the globe.<\/p>\n

In the Arctic, high levels of mercury are found in beluga whales, polar bears, seals, fish, eagles and other birds. This means that humans are also affected, particularly the Inuit<\/a>, who rely on traditional hunting and fishing for food. Exposure to high levels of mercury over long periods can lead to neurological and cardiovascular problems. Scientists have been working for more than two decades<\/a> to determine how mercury makes its way from industrialized countries to the Arctic.<\/p>\n

From atmosphere to plants to soil<\/h2>\n

From our observation site north of Alaska\u2019s Brooks Range, we determined that gaseous elemental mercury in the atmosphere is the dominant source of Arctic mercury. We calculated<\/a> that it accounted for 70 percent of the mercury that finds its way into tundra soil. Previous studies focused mainly on deposition of airborne oxidized mercury. However, we estimate that oxidized mercury accounts for less than one-third of mercury deposition, and deposition by rain and snow for only 2 percent.<\/p>\n

The next question is how gaseous mercury falls to the ground. We found that plants absorb it from the atmosphere in their leaves, much as they take up carbon dioxide. Then, when the plants shed leaves or die, the mercury they contain is deposited in soil. <\/p>\n

This likely explains why runoff from tundra soil to the Arctic Ocean \u2013 which other researchers have estimated totals 50 to 85 tons per year<\/a> \u2013 accounts for half to two-thirds of total mercury input into the Arctic Ocean. There, it can be converted to highly toxic organic methylmercury. As larger animals eat smaller animals, it biomagnifies through the aquatic food chain to harmful levels.<\/p>\n

It could get worse. Our study did not examine the potential impact of global warming, but if climate change continues unchecked, warmer temperatures could destabilize mercury deposits in permafrost soils <\/a> and allow even larger amounts to migrate into Arctic waters. <\/p>\n

\n \"\"<\/a>
\n Cumulative atmospheric deposition of major mercury forms in the Arctic tundra.<\/span>
\n Obrist et al, Nature 547, 201\u2013204 (13 July 2017).<\/a><\/span>
\n <\/figcaption><\/figure>\n

Fingerprinting mercury sources<\/h2>\n

We gathered our Arctic data year-round \u2013 a tall order in a place with long, dark winters when temperatures plunge to 40 degrees Fahrenheit below zero. Summers also pose challenges, especially with clouds of mosquitoes. <\/p>\n

We used a lab set up on the tundra, which we visited regularly to calibrate and service our instruments and to collaborate with staff from Toolik Field Station<\/a>, a research station operated by the University of Alaska at Fairbanks. Our instrumentation included measurements of all major forms of mercury in all environmental compartments, including the atmosphere, snow, rain, plants, lichen, mosses, and tundra soils and permafrost.<\/p>\n

Many of our instruments allowed continuous measurements throughout the year via remote control. We needed to measure mercury levels year-round in order to develop annual mercury deposition mass balances \u2013 estimates of how much mercury was entering the Arctic from different sources and where it goes. In addition, my collaborators from France performed measurements of stable mercury isotopes \u2013 a novel and powerful technique that allowed us to fingerprint various sources of mercury in the environment. <\/p>\n

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