Photograph of Rio Tinto. (Credit - Carol Stoker)
|- location||Gulf of Cádiz|
|Length||100 km (62 mi)|
The Río Tinto ("red river" in English) is a river in southwestern Spain that originates in the Sierra Morena mountains of Andalusia. It flows generally south-southwest, reaching the Gulf of Cádiz at Huelva.
Since ancient times, a site along the river has been mined for copper, silver, gold, and other minerals. In approximately 3,000 BCE, Iberians and Tartessians began mining the site, followed by the Phoenicians, Greeks, Romans, Visigoths, and Moors. After a period of abandonment, the mines were rediscovered in 1556 and the Spanish government began operating them once again in 1724. As a result of the mining, Río Tinto is notable for being very acidic (pH 2) and its deep reddish hue is due to iron dissolved in the water. Acid mine drainage from the mines leads to severe environmental problems due to the heavy metal concentrations in the river. In 1873, the multinational Rio Tinto Company was formed to operate the mines; by the end of the 20th century it had become one of the world's largest mining companies, although it no longer controls the Rio Tinto mines; these are now owned by EMED Mining plc.
The ore body was deposited in the Carboniferous (300-350 Ma) by hydrothermal activities on the sea floor. The river area has a history of mining activity since the Tartessans and the Iberians started mining in 3000 BCE. The mining continued over the Phoenician era and under the Roman Empire until the second part of the 15th century: primarily for copper but also for iron and manganese. In the nineteenth century the mining operation started in large scale mainly by mining companies from the United Kingdom. After the peak of production in 1930 production declined and ended for copper mining in 1986 and for silver and gold in 1996.
This river has gained recent scientific interest due to the presence of extremophile aerobic bacteria that dwell in the water. These life forms are considered the likely cause of the high acid content of the water. The subsurface rocks on the river bed contain iron and sulfide minerals on which the bacteria feed.
The extreme conditions in the river may be analogous to other locations in the solar system thought to contain liquid water, such as subterranean Mars. NASA scientists have also directly compared the chemistry of the water in which the rocks of Meridiani Planum were deposited in the past with the Río Tinto. Likewise Jupiter's moon Europa is theorized to contain an acidic ocean of water underneath its ice surface. Thus the river is of interest to astrobiologists.
Based partially on research done near the Río Tinto river, two NASA scientists reported in February 2005 that they had found strong evidence of present life on Mars (Berger, 2005). NASA officials denied the scientists' claims shortly after they were released, however, and one of the scientists, Carol Stoker, backed off from her initial assertions (spacetoday.net, 2005).