Scientists have warned that melting ice in Antarctica is releasing a "time bomb" of mercury that has been trapped in the ice for hundreds of years, posing a severe environmental threat to the region's pristine ecosystem.
The study, published in the journal PNAS Environmental Sciences, showed that mercury is currently accumulating in sediments off the coast of Antarctica at a rate of 93 micrograms per square meter per year, double the rate recorded on other continental shelves, despite the remoteness of the region.
Since the beginning of the Industrial Revolution, this rate has increased by 160%, which scientists believe is due to climate change caused by human activities.
Mercury is a heavy metal found naturally in trace amounts. Its vapors are emitted from volcanoes and tectonic activity, and then absorbed by phytoplankton in the ocean. This substance then moves through the food chain when fish eat these plants, or it settles on the seabed after the death of microorganisms.
Under normal conditions, this accumulation remains within safe limits, but human activities such as burning coal and manufacturing metals raise the percentage of mercury in the atmosphere globally, making its levels in the food chain threaten the health of animals and humans.
But scientists from Peking University confirmed that the high mercury levels in the air alone do not explain the large quantities detected off the Antarctic Peninsula; the main reason is the accelerated melting of the ice there.
The team explains this through two simultaneous processes:
First: Melting ice exposes wider areas of water, allowing phytoplankton to grow densely and absorb more mercury from the air.
Second: Warming accelerates the entry of mercury stored in ice into the ocean through meltwater and erosion.
The Antarctic ice sheets have trapped mercury from the atmosphere for thousands of years, but current melting is releasing unprecedented amounts. Since the start of the Industrial Revolution, the amount of mercury released with meltwater has increased by 550%, while the amount absorbed by the air has increased by 350%.
The Antarctic Peninsula stands out as the most affected region, since although it constitutes only 5% of the continent’s area, it contributes 60% of the ice mass lost from the shelves over the past thirty years, and currently about 90% of its glaciers are in decline far exceeding natural limits.
The situation is becoming increasingly dangerous given evidence that mercury has begun to seep into living organisms on the continent. A study published last year revealed that 62% of seabirds in Antarctica have mercury levels in their bodies that exceed the safe limit for health, and that a quarter of these species are at a moderate to high risk of mercury poisoning.
