The thawing of permafrost in the Arctic is releasing dangerous levels of mercury into waterways, potentially threatening the food chain, scientists warn.

Arctic permafrost is melting at an alarming rate, posing a serious threat to the food chain and the communities that rely on it, according to researchers at the University of Southern California who studied sediment transport in the Yukon River in Alaska.

As the Yukon River flows westward across Alaska towards the Bering Sea, eroding permafrost along its path is releasing sediment containing mercury into the water, according to a study published Thursday in the journal Environmental Research Letters . This mercury has likely been trapped within the permafrost for thousands of years, the scientists said.

"There could be a massive release of mercury in the Arctic waiting to happen," Josh West, professor of Earth sciences and environmental studies at USC Dornsife College of Letters, Arts and Sciences, said in a statement.

The researchers examined mercury levels in riverbank and sandbar sediments, digging down to deeper soil layers.

They also leveraged satellite remote sensing data to track the Yukon River's changing course. This is critical because it influences the amount of mercury-rich sediments eroded from riverbanks and deposited on sandbars, as the research paper highlights.

"The river can rapidly move large quantities of mercury-laden sediment," explained Isabel Smith, a USC Dornsife doctoral candidate and co-author of the study, in a statement.

The rivers are also re-burying a significant amount of mercury, leading the researchers to underscore the importance of understanding both the erosion and reburial processes.

The addition of these toxic metals presents an environmental and health threat to at least 5 million people residing in the Arctic, the researchers discovered.

West noted that the risk of contamination through drinking water is minimal.

"The situation is not comparable to Flint, Michigan," West stated. "The majority of human exposure to mercury is through food consumption."

However, the long-term consequences could be severe, especially for Arctic communities that rely on hunting and fishing, the researchers warned.

The impact is projected to intensify over time as the metal accumulates within the food chain, particularly through fish and wildlife that humans consume.

"Prolonged exposure, especially with escalating levels as more mercury is released, could have a significant negative impact on the environment and the well-being of those residing in these regions," Smith emphasized.

The Arctic is frequently recognized as the forefront of climate change, with existing research highlighting numerous repercussions that melting at the North Pole will have on the rest of the globe.

The region is experiencing a more rapid melting rate than anticipated , a study published in the Proceedings of the National Academy of Sciences last year determined. Daylight hours are increasing as both poles melt, redistributing the mass of water that is contributing to rising sea levels, a study published in PNAS in July concluded.

A recent analysis of fossils found beneath the Greenland ice shelf suggests that the region was once ice-free, indicating that the ice sheet is not as stable as previously believed, according to a study published earlier this month in Nature.

The melting of the Greenland ice sheet could put 400 million people at risk of flooding, a paper published in Nature in 2019 found.