The first source of methane under Antarctic sea ice

Due to the large sea ice around Antarctica, the sea floor of the Antarctic coastal areas is explored surfaces hardly. But just there, geoscientists suggests aro

The first source of methane under Antarctic sea ice

Due to the large sea ice around Antarctica, the sea floor of the Antarctic coastal areas is explored surfaces hardly. But just there, geoscientists suggests around a quarter of all the Methane of the earth's resources. "The Antarctic, could include it is estimated that between 80 and 400 gigatonnes of carbon in the Form of methane which is a substantial proportion of the global methane reservoirs in marine reservoirs," explained Andrew Thurber and his colleagues from Oregon State University. If the sea ice moves due to climate change and the sea will be warmer, could escape the potent greenhouse gas from the bottom of the sea, and a significant contribution to the further heating of the atmosphere afford.

discovery under the sea ice

But how likely is it that along the Antarctic coasts, methane-form outlets, is yet unknown. Also, how much passes from the exiting Gas down to the water and the atmosphere. Although methane sources of bacteria to eat away at most of the submarine for a large part of the methane before it escapes into the air. However, because in the Antarctic, yet there is no active source of methane was found, was this for this Region so far does not confirm or refute - until now. Because Thurber and his Team have now discovered the first active methane discharge in Antarctic waters and investigated. "This is a significant discovery that may help to close the large gap in our understanding of the terrestrial methane cycle", stresses Thurber. Tracked down, he and his Team are the source of methane in a surprising way, a point of the sea-bottom, has been since the 1960s, intensive research. It is located on the edge of the Ross ice Shelf is located off the coast of Ross island, including the active volcano Mount Erebus.

While up to the year 2010, this was to determine at this point, nothing Flashy, had changed this to 2011. Now, divers observed on the approximately ten meters under the sea ice to the underlying sea floor, a vast whitish bacterial Mat that extended about 70 meters in length and about a Meter wide was. "This microbial Mat is a clear indication that there is a methane leakage," explains Thurber. In fact, measurements showed that the water above the Mat is enriched with methane, and that methane out of the Sediment outlet. Thus, the researchers had discovered the first active source of methane in the Antarctic. But even more important: The discovery was made a short time after this gas had formed, which allowed the Team, for the first time, the development of a fresh source of methane in this Region to follow. "It was pure luck to find an active source of methane – and that's what we had," says Thurber.

Surprisingly slow colonization

For their study, the researchers have, in the course of five years, regularly to the bacteria samples taken from the Mat and the sediment and analyzed. In addition, they determined on the spot, how much the methane from the bottom of the sea outlet. The result: "according to Our calculations, the methane efflux from the Sediment is 5.1 liters per square meter per day," reports Thurber and his Team. "This indicates that this outlet is supplied by a substantial underground inflow of a gaseous fluid." Whether the methane comes from the bacterial decomposition of organic substances in the surface or possibly from the nearby volcano, however, is unknown. Why this outlet forms a long, drawn-out stripes on the sea floor, remains a mystery. The scientists suspect, however, that the nearby volcano might play a role: "The formation of a volcano can cause cones of slag often to various underground channels, which could explain the observed pattern of exits," says Thurber and his colleagues.

the investigations of The bacteria in the white Mat showed that the usual methane-consuming microbes settled on this Antarctic source of methane, apparently, only extremely slowly. "It took between one and five years for the microbial community responded to the Rise of methane to the Sediment," report the researchers. This was significantly longer than on other known sources of Methane. In addition, normally, most frequently represented group of anaerobic methane-consuming bacteria, was only represented even then only in relatively low proportion. "This leads us to two possible conclusions: there are species that do not belong to the previously known Methanzehrern, or we are in a very early stage of microbial colonization," conclude Thurber and his Team. Which statement would be true, you must now show observations in the coming years. Clearly This Antarctic methane seems to be but now:-the outlet is different than any previously known.

source: Andrew Thurber (Oregon State University, Corvallis) et al., Proceedings of the Royal Society B – Biological Sciences, doi: 10.1098/rspb.2020.1134

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Date Of Update: 24 July 2020, 14:27