The team led by João Canário, a professor at Instituto Superior Técnico and a researcher at the Centro de Química Estrutural (CQE), brought back to Portugal permafrost samples between 25 and 100 thousand years old, collected in the Arctic (in Fairbanks, Alaska, United States of America), during fieldwork that took place at the beginning of April. The research aims to estimate the amount and origin of mercury stored in permafrost, anticipating some of the consequences of climate change.

‘As global temperatures rise, especially in the Arctic, the temperature of permafrost also rises and it begins to thaw,’ explains the researcher. In the region explored, the permafrost is rich in organic matter and, when it thaws, “microbial degradation leads to the production of large quantities of greenhouse gases”. In addition to carbon, other heavy metals such as mercury were also stored there and ‘are now released into ecosystems with adverse effects on wildlife’. This work will also make it possible to assess the impacts of mercury release on the environment and propose mitigation or remediation measures.

The team – which also includes the Técnico PhD students Henrique Zilhão and Diogo Gonçalves – collected samples from lakes that are the result of permafrost degradation and also from a tunnel, the Vault tunnel, where the frozen ground has been intact for more than 100,000 years. ‘This tunnel was built to mine gold and today it’s a real-time machine where you can go back thousands of years,’ says João Canário, who found ancient remains and even a shattered mammoth skull.

The age of the samples collected will be determined more precisely with the help of researchers from the Center for Nuclear Sciences and Technologies (C2TN) at Técnico. In this way, it will be possible to relate the origin of the mercury in these soils to the age at which permafrost was formed. It will also be possible to estimate the amount of mercury stored in permafrost at a global level.

In 2023, João Canário led the first Portuguese team to carry out research in Greenland, where he also collected permafrost samples. He has been doing research for over a decade in the Arctic and Antarctic, where he studies the chemistry of permafrost degradation and its impact on boreal and southern ecosystems. Together with the researcher and professor Zita Martins, he coordinates the Minor in Extreme Environments at Instituto Superior Técnico, the first and only of its kind in Portugal.