Context:

The thawing of Arctic permafrost due to climate change is releasing significant amounts of toxic mercury into the environment. 

Key Findings: 

Mercury Release and Environmental Impact

• This sudden release of mercury in large amounts into the atmosphere from the permafrost regions is described (by researchers) as a “Mercury Bomb”.
• As permafrost thaws due to climate change, it could release a huge amount of mercury, which might have serious health impacts locally, regionally, and even globally.
• The results highlighted the importance of accurately capturing the dynamics of erosion and deposition for understanding mercury transport in Arctic rivers and how they will evolve in a changing climate.

About the study: 

• In a study published in Environmental Research Letters, researchers investigated the rate at which mercury trapped in Arctic permafrost is being released from the Yukon River basin in Alaska. 
• Their goal was to assess how soon a potential 'mercury bomb' could be triggered.
• To gain insight into the effects of erosion in the Yukon River basin, floodplain sediments were collected from two sites with discontinuous permafrost: - Beaver and Huslia (Alaska) between June and September 

Soil Type and Mercury Concentration

• The study discovered that mercury content was generally higher in finer sediment grains compared to coarser ones. 
• This finding suggests that certain soil types could pose greater environmental risks.
• Abrupt thawing events, such as landslides in the Arctic permafrost region, can quickly mobilize large deposits of sediment, potentially releasing significant mercury stores.

Indigenous Communities at Higher Risk

• Indigenous communities in the Arctic, particularly those in Alaska, are among the most exposed to mercury. 
• These communities rely on subsistence fishing, which has led to disproportionately high blood mercury levels due to dietary exposure. 
• Changes in mercury levels in Arctic waterways directly impact these communities, as well as the broader Arctic ecosystem and ocean.

Case Study: Thaw Slumps in Canada

• The study highlighted an example of thaw slump landslides in the terrestrial Arctic's permafrost region adjacent to a tributary of the Mackenzie River in Canada. 
• According to a study published in Nature Reviews Earth & Environment in March 2022, over 98% of atmospheric mercury is emitted outside the Arctic and transported there via long-range air and ocean pathways.

Mercury (Hg)

• It is a heavy metal, a global contaminant that poses significant health and environmental risks. 
• While it occurs naturally, human activities have greatly increased its presence in the environment.

Sources of Mercury Contamination

• Natural: Volcanoes, geothermal springs, ocean emissions
• Human Activities: Burning coal, waste incineration, industrial processes, mining, dental amalgams.