White spots caused by carbon dioxide being carried into the water from the lava on the Fimmvörduháls mountain range have been seen in river Hvanná in the highland resort Thórsmörk in Iceland.
The spots are an unusual sight and can prove to be dangerous because the gas collects within depressions near the water and can cause suffocation—not long ago a doctoral student suffered mild intoxication when taking samples from the river.
The carbon dioxide has formed precipitations at the bottom of the river, Morgunbladid reports.
“I would like to reiterate that it is a little risky to go near the water and people have to be careful,” said geologist Sigurdur Reynir Gíslason at the University of Iceland Institute of Earth Science.
“These are calcium precipitations similar to those created by geothermal heat—the carbon dioxide binds with the rock and sort of flows like an invisible cloud with the water."
“When calcium comes loose from the rock it forms these spots, which are certainly beautiful but the gas which flows above can be dangerous,” Gíslason stated, adding that such precipitations are common in the Geysir area but very rare in cold water.
The white spots in Hvanná were first noticed in June and have been monitored by geologists since.
