Researchers have long thought that freezing slows down chemical reactions. However, a recent study suggests otherwise. Published in the journal PNAS, scientists discovered that ice can dissolve iron minerals more effectively than liquid water. This finding may help explain why many Arctic rivers are turning orange as the planet warms.
The study, led by Jean-François Boily from Umeå University, found that ice at 14°F (-10°C) releases more iron from minerals than water at 39°F (4°C). Boily explains, “Ice isn’t just a solid block. When it freezes, tiny pockets of liquid water form between the crystals. These pockets act like miniature reactors, concentrating compounds and creating acidic conditions that can dissolve iron minerals even in very cold temperatures.”
The researchers focused on goethite, a common iron oxide mineral, and its reaction with natural organic acids. They observed that the freeze-thaw cycles accelerate this process. These cycles free organic compounds that were trapped in the ice, leading to more chemical reactions. Interestingly, while fresh and slightly salty water enhance this dissolution, seawater tends to slow it down.
The implications of these findings are significant. They extend to acidic environments like mining sites and coastal areas where iron minerals and organics interact. Boily and his team are eager to determine if their results apply to all types of ice containing iron.
“Climate change is increasing the frequency of freeze-thaw cycles,” says Angelo Pio Sebaaly, a graduate student and co-author of the study. “Each cycle releases iron from soils and permafrost into the water, potentially harming aquatic ecosystems and water quality.”
This research may also shed light on the disturbing trend of Arctic rivers changing color. The influx of soluble iron into these environments could be a key factor in this transformation. The study emphasizes that ice is much more than a passive component of our ecosystems; it plays an active role that deserves our attention in light of ongoing climate change.
Understanding these dynamic processes is crucial as we confront the challenges posed by a warming world. For more insight into how climate change is impacting water quality, consider exploring additional resources from agencies like the Environmental Protection Agency.
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Chemistry,Climate change,Rivers
