Clip of the Week – source of the Rio Tinto river

Clip of the Week

This week’s clip is a tracking aerial shot of the source of the Rio Tinto river, Andalusia, Spain. It was filmed in January 2019 by Milan Radisics. Rio Tinto translates as Red River, as the river is coloured by oxidised iron and other minerals leaching from the surrounding terrain. The river maintains this colour for around 50km, before both the colour and the mineral content of the water start to decline.

The chemistry behind the process

Acid conditions in the area dissolve minerals and heavy metals, which then leach into the water and cause environmental problems. (The river has a pH of around 2, a strong acid roughly equivalent to vinegar). It is not clear how much of this acidity is natural, and how much results from ore mining – for gold, copper and silver, amongst other minerals – in the area. Although the river represents a harsh environment for life, some microorganisms classified as extremophiles do thrive in these conditions. Such life forms include certain species of bacteria, algae and heterotrophs.

As Milan comments,

“I am not sure how mining processes also affected the acidity of water, but as I saw, nature and human presence is so interwoven in this area it’s hard to separate the two…”