What are geological discoveries

Swiss geologists have discovered a white stream. Hidden in a valley in the Engadine near the Italian border flows the strange little river called Ova Lavirun. A snow-white layer covers its streambed for over a kilometer. The glowing color can even be seen on satellite images. But since there are hardly any hiking trails through the valley, the river has so far remained undiscovered. A team led by geologist Christoph Wanner from the University of Bern has now examined the whole thing in more detail.

It is flakes of aluminum compounds that give the stream its white color, the researchers write in a study in the specialist magazine Geochimica et Cosmochimica Acta. The mineral initially dissolves from the rock in a tiny form, as the pH value of the river at its source is acidic. A few hundred meters further on, however, the water mixes with small inflows from the mountains and the pH value suddenly becomes neutral again. As a result, the aluminum flocculates in the form of aluminum hydroxysulphate - and is deposited in the stream bed in snow-white particles.

The white flakes bind arsenic

The white flakes hide another secret: The well-known poison arsenic is bound in them, Christoph Wanner and his team discovered. Because of the acidity of the water in the source region, it is also released from the rock. The aluminum particles then bind it and remove it from the water by being deposited. So the arsenic cannot pollute the environment.

This system may also work for other toxins, write the geologists in their study. Thus the phenomenon of the white brook could possibly be used for water treatment in order to remove environmentally harmful substances.