For decades it was assumed that the extreme cold of the Arctic slowed down chemical reactions in the soil. However, a recent study by the University of Umeå (Sweden) has shown the opposite: ice at -10°C can release more iron from minerals than liquid water at 4°C.
This finding reconfigures the scientific narrative about geochemical processes in frozen regions and poses new ecological challenges in the context of climate change.
Liquid pockets in the ice: invisible and highly active reactors
At temperatures as low as -30°C, microcapsules of water form that accelerate mineral dissolution.
The key lies in the internal structure of the ice. At subzero temperatures, microscopic pockets of liquid water are generated between the ice crystals.
These capsules act as hyper-concentrated and acidic chemical reactors, capable of dissolving minerals like goethite, an iron oxide present in soils and rocks.
The Swedish team’s experiments showed that at -10°C, the release of iron was significantly greater than in liquid conditions.
Oxidized rivers and altered landscapes: visible signs of change
In Alaska, rivers acquire rusty orange tones due to the increase in dissolved iron.
In regions like the Brooks Range (Alaska), rivers are showing a intense orange coloration, reflecting the increase in dissolved iron in the water.
This phenomenon is not superficial: it indicates a profound alteration of the geochemical balance, with direct consequences on water quality, aquatic biodiversity, and human health.
Beyond melting: ice as an active source of pollution
Until now, the release of iron was attributed to the thawing of permafrost. But this study reveals that the ice itself, without melting, can be an active agent in the dissolution of minerals.
Moreover, the freezing and thawing cycles, increasingly frequent due to global warming, intensify the process, also releasing arsenic and other heavy metals trapped in the frozen soil.
Ecological and social impacts: a silent threat
Acidic and oxygen-poor rivers affect fish, insects, and human communities.
The effects are already visible: low levels of dissolved oxygen, high acidity, and alteration of aquatic habitats.
This harms riparian species and poses a direct threat to communities that depend on river and stream water for consumption, fishing, and agriculture.
A global phenomenon? Implications for glaciers in the Andes and Scandinavia
Researchers warn of similar processes in other cold mountain regions.
This phenomenon could also be occurring in glacial areas of Scandinavia, the Alps, and the Andes, where the frozen soil acts as a latent chemical reservoir.
The acceleration of these processes poses new challenges for the conservation of mountain ecosystems and water management in vulnerable contexts.
