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Author Topic: Pollution in the Arctic  (Read 2400 times)

wili

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Pollution in the Arctic
« on: November 07, 2015, 08:17:26 PM »
(Mods, please merge this if there is already a thread on this general topic.)

One of the changes we will see as things melt and thaw in the Arctic is new toxins entering the system, or at least in newly high levels of concentration. And of course there will be many other sources of pollution as oil exploration and shipping increase, wildfires rage, and other pollutants make their way to the top of the world. While obviously something that will affect the wildlife there, it seemed to me to be a discreet topic worthy of its own thread. Here's one article to kick it off:

Arctic Mercury Pollution To Increase as Permafrost Thaws

http://barentsobserver.com/en/nature/2015/10/arctic-mercury-pollution-increase-permafrost-thaws-13-10

Quote
Thawing Arctic permafrost may well unleash a new wave of toxic mercury pollution, say scientists, contributing to ongoing mercury poisoning issues in parts of the region.

Mercury poisoning harms wildlife and causes developmental and neurological damage in human fetuses and children.

These soils were frozen year round as recently as 10 to 20 years ago, but now thaw and re-freeze annually, said lead author Dwayne Elias, a microbiologist with the Oak Ridge National Laboratories, a federally-owned research center in the United States.

As the freeze-thaw cycle continues in coming years, he said, bacteria that contain the genes needed to convert inorganic mercury to its toxic form, called methyl mercury, will “wake up from being dormant for thousands and thousands of years.”

Groundwater will transport this methyl mercury into rivers and streams that game animals such as moose and caribou drink from, he said. Those water flows will also carry the mercury into coastal habitats of marine mammals and fish.
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Neven

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Re: Pollution in the Arctic
« Reply #1 on: November 08, 2015, 06:37:28 PM »
Wow, yet another change up North causing mercury levels to increase in the Arctic (also see these two ASIB blog posts from 2012 and 2014).
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vox_mundi

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Re: Pollution in the Arctic
« Reply #2 on: October 19, 2018, 05:42:54 PM »
Arctic Mercury Mystery: Solved

Quote
In the Canadian Arctic, a mystery has troubled scientists and local communities for decades: Why do marine animals in the western Arctic have higher mercury levels than those in the east?

The trend is seen throughout the food web, from the tiny zooplankton that drift along ocean currents to large mammals like polar bears.

Prior research suggested that marine animals in the western Canadian Arctic contain more mercury because the region receives more mercury from a variety of sources, including atmospheric emissions from eastern Asia, river discharge from large watersheds such as the Mackenzie and coastal erosion and permafrost thawing.

However, the mercury from all these sources exists almost exclusively in its inorganic form, as mercury vapour and mercury that is bound to dust particles, for example.

Once it's in the ocean, however, some inorganic mercury can be converted to an organic form, called methylmercury. Not only is methylmercury taken up more efficiently by plankton and other microorganisms, but it can build up, or bioaccumulate, in organisms as it moves along the food web through a process known as biomagnification. As it does, it tends to inflict more harm on predatory fish, birds and mammals.

For more than a decade, scientists have suspected that the most important factor controlling mercury levels in Arctic marine animals is not where the mercury comes from (sources), but, rather the conversion of inorganic mercury to methylmercury in the ocean (processes).

As part of ArcticNet, a Canadian research network, in conjunction with the Canadian Arctic GEOTRACES program researchers aboard the icebreaker, CCGS Amundsen, analyzed seawater samples collected at various depths along a 5,200-kilometre transect that began in the Labrador Sea in the North Atlantic Ocean, transited through the Canadian Arctic Archipelago and continued to the Beaufort Sea and the Canada Basin in the west.

Our results found that the concentrations of total mercury – inorganic mercury plus methylmercury—are generally lower in the western Canadian Arctic than in the east. This runs counter to mercury trends observed in marine animals.

Methylmercury, on the other hand, shows very revealing distribution patterns: its concentration is lowest at the sea surface, increases to a maximum at depths between 100 and 300 meters, and then decreases towards the bottom of the ocean.


This pattern, where an ocean layer below the surface is enriched with methylmercury, has been seen in other oceans. What makes our discovery different is that the "methylmercury-enriched layer" in the Arctic occurs at much shallower depths than elsewhere.

We also found that the peak concentration of methylmercury in the enriched layer in the Canadian Arctic is highest in the west and lowest in the east, mirroring the mercury trend in marine animals.

The shallowness of the methylmercury-enriched layer is important, as it lies within the habitat of zooplankton and other organisms near the bottom of the food web. This allows methylmercury to be readily taken up by these animals, and subsequently biomagnified in mammals.
I wonder if this is related to recent changes in salinity and temperature at 100-300m depth in the western Canadian Arctic.

Arctic Sea Ice Decline Driving Ocean Phytoplankton Farther North
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