GEOGRAPHY

Chinese scientists have found that volcanic-hydrothermal systems can breed microbial communities


Recently, the international academic journal “Journal of Geophysical Research-Ocean” reported the latest research results of the ultra-acidic volcanic-hydrothermal system of the Institute of Oceanography of the Chinese Academy of Sciences in the post-Manus arc basin in the western Pacific Ocean. Through in situ comprehensive quantitative detection and microbiome analysis, researchers have found that the volcanic-hydrothermal systems widely distributed around the world are rich in hydrogen, and have bred microbial communities that can use hydrogen, which has important implications for exploring the origin of life.

“Discovery” ROV carries out laser Raman comprehensive in situ exploration Photo courtesy of the Institute of Oceanography

The deep-sea volcano-hydrothermal system is mainly formed by the direct mixing of volatile gases of seafloor magma with seawater or submarine volcanic eruptions, which is a typical “white smokestack” and is widely distributed around the world. At the same time, volcanic-hydrothermal systems have also given birth to unique biomes, but the relationship between biological metabolic processes and fluids is not clear. The traditional method of “sampling first and then analyzing at room temperature and pressure” will cause obvious changes in the composition and parameters of hydrothermal fluids, so in situ detection and obtaining in situ parameters of fluids is an important guarantee for studying the relationship between the two.

DESMOS CRATER IN THE POST-MANUS ARC BASIN IN THE WESTERN PACIFIC PHOTO COURTESY OF THE OCEANOGRAPHIC INSTITUTE

The team of Zhang Xin, a researcher at the Institute of Oceanography, and the team of Sun Li took the volcanic-hydrothermal system developed in the DESMOS crater in the post-Manus arc basin in the western Pacific Ocean as the research target, and used the “Discovery” ROV to carry out in situ Raman comprehensive detection and fluid and biofidelity sampling in the hot spring vent area and the newly discovered Faxian overflow area during the voyage, respectively.

It was found that the ultra-acidic high-temperature fluid formed in the hot spring area composed of andesite contained a large amount of hydrogen at concentrations as high as 8.56 mmol/kg. The neutral cryogenic fluid in the Faxian overflow zone of the same crater is hydrogen sulfide-free and rich in hydrogen sulfide at a concentration of 7.78 mmol/kg. In view of this special phenomenon, based on in situ quantitative results and thermodynamic simulation calculations, the research team believes that different fluid-rock interactions occur in the two regions due to the difference in the degree of seawater mixing.

By further microbiome analysis of the samples, the team found that there were different microbial communities in the hot spring vent area and the Faxian overflow area, and that the microorganisms in the hot spring area could use hydrogen, while the microorganisms in the Faxian area mainly used hydrogen sulfide oxide as an energy source, indicating that in a volcanic hydrothermal system, even fluids from the same magma source can breed different microbial communities.

Based on laser Raman in situ quantitative detection technology, the voyage reported for the first time that the hydrogen concentration of the super-acidic volcano-hydrothermal system dominated by volcanism can reach the millimolar level, and provides an important material source for the chemical energy ecosystem nurtured by it. In the past, hydrogen-rich fluids were mainly formed by serpentinization reactions between ultramafic rocks and mafic rocks, and the “Lost City” alkaline hydrothermal system in the Atlantic Ocean produced a large amount of hydrogen due to serpentinization reactions, providing an important place for early life. However, the global alkaline hydrothermal system is currently only “Lost City”, which is not universal, and the frequent occurrence of submarine volcanoes in the early days of the earth has given birth to a widely distributed acidic volcanic-hydrothermal system, and the study has important implications for exploring the origin of life. (Source: China Science News, Liao Yang, Wang Min)

Related paper information:https://doi.org/10.1029/2023JC019703



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