It’s a ticking time bomb, set to go off with global warming: trapped in the permafrost of Northern Hemisphere lies more than twice the amount of mercury in the rest of the earth.

A warming climate could release large amounts of this dangerous toxin that has serious health effects in humans and animals, ranging from neurological problems, damage to various organs to birth defects.

Scientists warn that rising air temperatures due to climate change could defrost the existing permafrost layer and this could release a large quantity of mercury that could potentially affect ecosystems around the globe, phys.org reported.

The findings, published in Geophysical Research Letters, found 793,000 tonnes of mercury in frozen permafrost soils and another 863,000 tonnes in unfrozen soils in the northern permafrost region. Combined, this is equivalent to 122,000 litres of liquid mercury – an amount that is about 10 times the total industrial mercury emissions in the last 30 years or so and makes it the largest reservoir of mercury on the planet. Currently, humans emit about 2,000 tonnes of mercury every year through industrial activity, said Down To Earth.

‘Permafrost’ is defined as any soil that has been frozen for more than two years. In the Northern Hemisphere, permafrost accounts for about 8.8 million square miles (22.79 million square kilometers) of land — or roughly 24 percent of exposed Earth, according to the National Snow and Ice Data Center, said LiveScience.

Over time, naturally occurring compounds in the atmosphere, such as mercury and carbon dioxide, can bind with organic material in the soil and be frozen into permafrost, potentially remaining trapped underground for thousands of years before it thaws, said the new study.

Researchers also point to the fact that this large amount of mercury might pose a danger to the environment. Mercury has negative reproductive and neurological effects on animals and is known to accumulate in both water and terrestrial food chains.

“There would be no environmental problem if everything remained frozen, but we know the Earth is getting warmer,” study author Paul Schuster, a hydrologist at the U.S. Geological Survey in Boulder, Colorado, said in a statement. “This discovery is a game-changer.”

Researchers have already observed climate-change-induced permafrost thawing, and there is likely more on the way: According to a 2013 study, the Northern Hemisphere will lose anywhere from 30 to 99 percent of its permafrost by 2100, assuming current human greenhouse-gas emissions continue unabated.

Previous studies have attempted to account for the billions of tons of carbon dioxide, methane and even “zombie pathogens” that could be loosed into the air and the oceans by melting permafrost. The environmental impact of a large-scale mercury leak, however, remains an unpredictable problem.

One major concern is that this trapped mercury could seep into nearby waterways and transform into methylmercury, a toxin that can cause motor impairment and birth defects in animals, Edda Mutter, science director for the Yukon River Inter-Tribal Watershed Council, said in a statement, according to media reports. Such contamination could travel swiftly up the food chain from microorganisms to humans, said Mutter, who was not involved in the new study.

The researchers are currently working on a follow-up study modeling the release of permafrost due to climate change, according to the statement.

MERCURY POISONING (Excerpted from LiveScience)

When mercury is released into the atmosphere, it is dissolves in fresh water and seawater.

Mercury in humans may cause a wide range of conditions including neurological and chromosomal problems and birth defects.

A type of mercury called methylmercury is most easily accumulated in the body is and is particularly dangerous.

About 80 to 90 percent of organic mercury in a human body comes from eating fish and shellfish, and 75 to 90 percent of organic mercury existing in fish and shellfish is methylmercury, according to a paper published by the Journal of Preventative Medicine and Public Health. (See below for mercury levels in types of fish)

Health effects

Mercury poisoning is a slow process that can take months or years, according to the National Institutes of Health (NIH). Since the process is so slow, most people don’t realize they are being poisoned right away. Mercury from food sources is absorbed into the bloodstream through the intestinal wall, and then carried throughout the body.

The kidneys, which filter the blood, can accumulate mercury over time. Other organs can also be affected.

Negative health effects from methylmercury may include neurological and chromosomal problems. According to the NIH, long-term exposure to organic mercury can cause:

uncontrollable shaking or tremor

numbness or pain in certain parts of the skin

blindness and double vision

inability to walk well

memory problems

seizures

death with large exposures

Most notable are the effects of mercury on the brain.

Mercury poisoning can result in hearing and vision changes, personality changes, memory problems, seizures or paralysis.

When children are exposed to mercury, they may have developmental or muscle coordination problems.

The toxicity of methylmercury may also have reproductive consequences.

Pregnant woman who eat fish and seafood contaminated with methylmercury may have the increased risk of having a miscarriage, or having a baby with deformities or severe nervous system diseases. These birth defects can happen even if the mother doesn’t seem to be poisoned.

Symptoms of mercury poisoning (Excerpted from Scientific American)

There are NO specific symptoms and it can be confused for something else.

Unfortunately in mercury, symptoms can look like many disease states. When levels are building up,  there could be a variety of symptoms that a physician may interpret as another illness.

Only when the physician can’t find a real cause or gets a toxicologist involved will they do blood tests and say, “Yes, this is probably due to mercury exposure.”

It’s a difficult diagnosis. You have to know by history that a person has been exposed to this and put two and two together. No specific set of symptoms will say, “Ah, this is mercury poisoning.”

If it’s mercuric salts the person has been poisoned by, it may just be a problem with the kidneys, issues with the ability to urinate, or they’re feeling out of whack because of renal dysfunction.

If someone is inhaling fumes from elemental mercury, that can show up as an upper respiratory illness, like a flu, at first. They might find they can’t concentrate well, have trouble with fine motor control or their perception of smell, eyes or touch. If it was affecting their heart, it could be palpitations or just in general not feeling well. If something is not going well with their blood cells forming, they may have issues similar to anemia, feeling very tired, easy bleeding or bruising.

With organic mercury exposure, the symptoms are pretty much the same, but probably not respiratory. The nervous system effects are what someone would see first.

Fish low in mercury

Anchovies (Nethili in Malayalam), Butterfish (Pomfret), Catfish (Singhara), Clam, Crab, Herring (Hilsa), Mackerel (bangada), Oyster, Salmon (Indian salmon is rawas), Sardine, Scallop, Shrimp, Sole, Squid, Tilapia, Trout, Whitefish 

Moderate mercury (Eat six servings or fewer per month; pregnant women and small children should avoid these)

Bass, Carp (Rohu), Cod (Gobro), Lobster, Snapper, Tuna (Canned Chunk light) 

High mercury (Eat three servings or less per month; pregnant women and small children should avoid)

Bluefish, Grouper (Kalava in Malayali), Sea Bass (Asian seabass is bhekti), Tuna (Canned Albacore, Yellowfin),

Highest mercury (avoid eating)

Shark, Swordfish, Tuna (Ahi)