If there is an element on Earth that has been shown to be dangerous for neurological health, it is mercury (Hg), a metal that is part of the planet and whose most important deposits are in China, Indonesia, or Tajikistan, although there is also a great mine, in Almadén, which places us on the map. What was not in the global 'budgets' of mercury was the land under the Greenland ice, which through the glacial basins is reaching the Arctic Ocean, altering its composition and posing a serious danger, given its toxicity, for fauna that lives there and, therefore, for human populations.
The alarm was raised this week in the journal Nature Geoscience by a score of researchers from different American and European institutions, in a study where they detect "extremely high concentrations of dissolved mercury found in meltwater rivers."
Scientists had already detected a striking increase in mercury, which is bioaccumulative, in marine organisms. Hence, an investigation began in the nearly 4,000 square kilometers that cover three glacial basins: Russell Glacier, Leverett Glacier, and Isunnguata Sermia, in addition to the three fjord systems (Nuup Kangerlua, Ameralik Fjord, and Søndre Strømfjord, receiving substantial meltwater inflows). All of them are in the southwest area of the ice sheet of the great frozen island, where water samples were collected in the summer seasons of different campaigns.
The results leave no room for doubt: the concentrations of dissolved mercury found in natural waters and the mercury yields of these glacial basins are two orders of magnitude higher than those of Arctic rivers in other areas. It is estimated that the dissolved mercury from the southwestern region of Greenland represents approximately 10% of the estimated world fluvial flow for this element, specifically 42 tons per year, including the export of bioaccumulative methylmercury.
Led by the North American John Hawkings, the team also found high concentrations across the salinity gradients of the fjords, becoming the highest ever recorded, much higher than in other mountain glaciers such as the Himalayas. “The results suggest a geological source of mercury in the ice-sheet bed. They are high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting the urgent need to better understand the dynamics of mercury in ice sheet runoff under global warming ”, they say in the article published now.
The urgency for further studies lies in the high toxicity of mercury, which could be in the ice sheet, and that this layer is melting at a faster rate in recent years due to climate change. Moreover, according to another work published these days in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), this melting of the Arctic is already reaching the dangerous "point of no return", that is, the point at which snowfall is less than the amount of ice melting. It is a process that occurs mainly in the lowest areas, which are closest to the fjords.
The point is that now it is not only known that this ice made into the water could increase the sea level by up to seven meters, displacing millions of people, but that it will also arrive contaminated by hundreds of tons of mercury, which is not destroyed but accumulates. in living organisms, either from fish or from humans who eat those fish. To use a more technical word, it biomagnifies in aquatic food webs, mostly through the consumption of shellfish. The socioeconomic cost of its impacts has even been quantified at more than 5,000 million dollars a year, figures that can skyrocket as the thaw increases, as is happening.
Image Source - https://watchers.news/2012/05/25/circumpolar-rivers-responsible-for-toxic-mercury-accumulation-in-the-arctic-ocean/