Rio Tinto (river)

The ore body was deposited during the Carboniferous period (300–350 Ma) by hydrothermal activities on the sea floor. The history of mining in the Río Tinto area traces back to the Tartessans and the Iberians starting mining in 3000 BC, followed by the Phoenicians, Greeks, Romans, Visigoths, and Moors. The Río Tinto region has been the source of approximately 5,000 years of ore extraction, Despite these issues, the permit was ultimately granted in January 2015 and commercial production of copper restarted in February 2016. == Origin and ecology ==

Due to the extreme conditions of the river, there is very little in the way of life, with the exception of small amounts of microorganisms, including algae. The presence of anaerobic bacteria in the sediments is thought to contribute somewhat to the river's famously low pH (acidity), that in turn increases the concentration of dissolved heavy metals. The waters from the Río Tinto, high in metal sulphides, provide an ideal environment for chemolithoautotrophic microorganisms, with the sulphides acting as a food source. The product of metal sulphide metabolism through oxidization is ferric iron and secretion of acidic liquid. The continuation of this process for an extended period of time is thought by some scientists to be responsible for keeping the river's pH between 2 and 2.5 in most areas. Even in the extremely acidic water, both red and green algae have been observed to thrive in relatively high concentrations. Despite algae levels in the Río Tinto accounting for over half of the total biomass in the river, algae is understood to have minimal effects on the characteristics of the complex ecosystem. On the other hand, it is known that toxic water emanates from these vast underground and open pit mines and chemical ore refinement that had been active off and on for thousands of years. While it is still undetermined if the unique water chemistry of the Río Tinto developed as a result of thousands of years of mining or by natural causes, it is possible that the river's chemical makeup is due to the combination of both natural causes and acid mine drainage. The river drains an area with huge deposits of sulphides which was formed more than 350 million years ago. When sulphides are exposed to air, water, and microorganisms, drainage from acidic rocks flows into surface and ground water. Mining, however, greatly increases exposed areas. ==Astrobiology==

This river has gained recent scientific interest due to the presence of extremophile anaerobic bacteria that dwell in the acidic water. The subsurface rocks on the river bed contain iron and sulphide 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 groundwater on Mars. Scientists have also directly compared the chemistry of the water in which the Mars rocks of Meridiani Planum were deposited in the past with the Río Tinto. Likewise, the moon Europa contains an acidic ocean of water underneath its ice surface, thus the Río Tinto river is of interest to astrobiologists studying the environmental limits of life and planetary habitability. ==See also==