Scientists found dissolved mercury in rivers and fjords in Greenland just as much in far more industrialized areas. The presence of the heavy metal now raises concerns for the health of indigenous communities. With global warming, the problem may get worse.
GREENLAND — Despite its seeming pristine characteristics and remoteness, with no industrial activity, not even any source of pollution, scientists found that runoff water from three different glaciers in southwest Greenland contains mercury as much as is present in water in highly industrialized areas.
“Mercury concentrations this high would usually only be seen in quite contaminated systems. We compare it to contaminated rivers in China, because that’s where similar kinds of concentrations have been found before,” says British environmental geochemist Jon Hawkings, DW reports. Hawkings is also lead author of the study published in Nature Geoscience.
One to 10 nanograms per liter (ng L-1) are the normal amounts of dissolved mercury in rivers. Hawkings says that is comparable to “a grain of sand in an Olympic size swimming pool.” The water samples from southwest Greenland, however, show far higher average values of 150 ng L-1, researchers say.
But unlike what is seen in China, the evidence reveals that the mercury in Greenland come from natural geological sources in the ice sheet bed.
Scientists took water samples in 2012, 2015, and 2018 with their observatations affirming what they had initially taken in 2012, that high concentrations of mercury is present. They analyzed samples from meltwater rivers and fjords and found concentrations of dissolved mercury among the highest ever recorded.
“I just didn’t quite believe it! Because the numbers were so high, it was so unexpected,” says Hawkings said. “As a scientist, there was an element of excitement, of finding something new that nobody else had looked at before. But also concern.”
Mercury is toxic
The World Health Organization (WHO) classifies mercury (chemical symbol: Hg) as one of the top 10 chemicals of major public health concern. Numerous health problems can result from even minimal exposure to it. Reported health problems caused by exposure are toxic effects on the nervous, digestive and immune systems, as well as in organs such as lungs, kidneys, skin and eyes.
Mercury is a toxic heavy metal that naturally occurs in air, water, and soil, through volcanic eruptions. Human activity, however, amplifies its presence through pollution. Coal power plants and gold mining responsible for most of the mercury released into the environment.
Seafood consumption is one of the main reasons for overexposure to mercury. It accumulates in organisms and enters the aquatic food chain as methylmercury, its most toxic form.
Governments agreed to the Minamata Convention on Mercury in 2013 because the concerns about the consequences of mercury to the environment and its effects on humans are so significant to be ignored. Addressing the anthropogenic (human-caused) mercury emissions and phasing out a variety of products containing mercury—such as batteries, fluorescent lamps, and thermometers-were required. The global treaty entered into force in 2017.
However, Hawkings points out, the Minamata Convention “doesn’t take into account these climatically sensitive natural sources that are much more difficult to manage than, say, closing a coal-burning power plant.”
His study implies that the international community should start focusing on the issue.
Glaciers are melting
One more concern is the increasingly steady melting of glacial systems. As mercury also naturally originates from the southwest Greenland ice sheet bed, it could be true to other parts of the island as well. About 10% of the world’s land area is covered by glaciers.
“Glaciers melting may mean more mercury in rivers and potentially in coastal systems,” he says. It could potentially affect Greenland’s indigenous people who heavily rely on fishing both as food source and economic activity, being a major exporter of shrimp, halibut, and cod.
The study only measured the concentration of mercury in water samples, how much of it is in the food web is uncertain. It is difficult to assess the risk.
“It’s unclear yet just how dangerous the situation is for Indigenous populations of Greenland at the moment,” says Hawkings.
Hawkings believes it is imperative and urgent to learn more about the Arctic systems and how wide the effect is in Greenland, how the coastal ecosystems work.
“If the ice sheet is a source of mercury and it could exacerbate some of those effects, then people need to know about it and how to manage it,” Hawkings says. (TC/The MiNT)
Featured image: After draining, lakes leave behind holes called ‘moulins’, which allow meltwater to continue to travel to the bottom of the ice sheet. Courtesy Phys.org /Photo by Charlie Schoonman