At the mouth of Rio Tinto in southwestern Spain, acidic river water contaminated with heavy metals from ore mining and mineral weathering mixes with saltwater from the Atlantic Ocean. Here, microorganisms that love such extreme conditions form a unique community. They live in water as acidic as vinegar, are resistant to high salts, and some also deal very well with high levels of toxic metals. This community was discovered by a research team led by Professor Andreas Kappler and Assistant Professor Sarah Kleindienst of the Center for Applied Earth Sciences, University of Tubingen. Researchers have investigated where microorganisms obtain energy for metabolism under extreme conditions and how they affect the deposition or dispersion of heavy metals in the Rio Tinto estuary.The study is published in the latest version of Applied and Environmental Microbiology..
Rio Tinto is called the “Red River” for good reason. This river in the province of Huelva, Spain, has a place that glows from orange to bright red along a course with a total length of about 100 km. Even today, it is not clear why Rio Tinto’s water is so acidic that its estuary is one of the most heavily polluted water systems in the world with toxic metals.
Ore mined as early as the Chalcolithic
“The pollution here began very early in the Chalcolithic 5,000 years ago,” reports Sarah Kleindienst. Still, people were mining ore upstream of the river above the pyrite belt in the southern Iberian Peninsula. Rockbelts contain gold, silver, copper, tin, lead, iron, and large iron sulfide deposits. When the ore was mined, iron sulfide came into contact with oxygen in the air, allowing certain microorganisms to oxidize iron and sulfur. “This produces bloody red, highly acidic water that dissolves large amounts of other toxic metals such as manganese, cobalt, nickel, and cadmium from rock each year and flushes them into the river,” she says. ..
According to a study by the Tübingen team, most microorganisms in river water draw energy from dissolved iron. “In the process, they form iron minerals and precipitate other toxic metals around the cell wall. These cell and mineral aggregates are transported downstream to the estuary,” Andreas Coupler said. say. “I was particularly interested in what happens when acidic river water mixes with seawater there.”
He adds that high concentrations of chloride from seawater are toxic to acid-loving iron-oxidizing microorganisms. “Most of them disappear at the estuary, where other iron oxidizers that can cope with high salinity take over. In addition, the high levels of iron dissolved in the estuary attract the seeds of marine iron oxidizer,” Klein said. Schmidt explains. They also form iron minerals at the estuary and precipitate toxic metals such as arsenic and chromium that deposit in Riotint deposits. However, some of these minerals are further transported to the edge of the ocean, and Kleinschmidt says, “By gaining insight into this microbial community, we can learn more about the effects of microorganisms on the mobility of toxic metals in Rio Tinto. “I add.
Mars-like conditions fascinate astrobiologists
Rio Tinto’s iron-oxidizing bacteria form colorful minerals such as goethite, hematite, Schwertmanite, and jarosite, which deposit in river sediments. “Interestingly, the same mineral was discovered by the Mars rover Curiosity in the deposits of the strong wind Mars crater, where the formation of such minerals was 4.1-3.7 billion years ago, similar to that of a large river. It may have been caused by acid-loving craters. A system like Riotint, “said Sergei Abramov of the University of Tubingen, the lead author of the study. At that time, Mars would have had a damp condition and a milder temperature.
“In fact, Rio Tinto is attracting astrobiologists from around the world to study fictional life on Mars,” Kappler adds. He also sees other similarities between the Rio Tinto estuary and Mars. At the mouth of Rio Tinto, Atlantic tides cause a periodic mix of acidic river and seawater. On Mars, a similar process may have occurred in the active sediment cycle of the Gale Crater 3.7-3.6 billion years ago.During this period, the Martian lake and river system was also regularly depleted, and Rio Tinto’s climate changed. Estuary The system causes the corresponding seasonal dryness of the floodplain, says Kappler.
Sergey M. Abramov et al, Biogeochemical niche of the iron circulation community affecting heavy metal transport along Rio Tinto, Spain, Applied and Environmental Microbiology (2021). DOI: 10.1128 / aem.02290-21
Quote: Researchers have obtained the Rio Tinto Microbial Community (February 23, 2022) from https: //phys.org/news/2022-02-gain-insights-rio-tinto-oxidant.html on February 23, 2022. Get insights on the day)
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Researchers gain insight into Rio Tinto microbial communities
Source link Researchers gain insight into Rio Tinto microbial communities