Termites recycle their methane – scientists want us to copy them

Termites, as cattle and other herbivorous animals, work with special bacteria in their gut to break down food. It's a good deal: they eat plants that most competitors can not handle, but it produces a lot of methane during digestion.

It's not really a problem for the mound, but for us. Methane is about 30 times more potent as a greenhouse gas than carbon dioxide and is an important contributor to climate change. Termites generate about 1 to 3% of global methane emissions, or about 20 million tonnes of gas each year. However, it is much less than what they actually produce. TA new paper reports that mounds have built-in filtration systems that purify methane before it reaches the atmosphere.

Pets termite

A team of researchers led by Dr. Philipp Nauer of the School of Ecosystem and Forest Sciences of the University of Melbourne reported that about half of all methane emitted by termites is broken down by bacteria in the mounds and the underlying soil. Methane is a good source of energy and, as such, invaluable for life, says co-author Stefan Arndt, a professor at the University of Melbourne. A group of bacteria called methanotrophs live in the soil and consume methane as their main source of energy.

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"They are in your garden, in your city, in your forest, even in agricultural soils," says Professor Arndt. "The logic would tell you that there should be these methanotrophic bacteria also in termites because they are everywhere."

Dr. Nauer's team has had to develop new techniques to accurately map the treatment of methane in a mound. This task was particularly difficult, he said, because "there are three processes in the methane cycle – production, transportation and consumption – at the same time and in the same place", which makes it difficult to follow the individual steps of the methane cycle. process.

"In soils with a source of methane, for example rice fields, you often have separate areas where you have methane production or consumption, with transportation between them, but in termites, it's much more complex. You do not know where the termites are, so you do not know where the production is. "

Other difficulties it's lifted of the properties of the mounds themselves. They are never uniform structures, they are porous (but not so porous everywhere) and they are riddled with complex networks of canals and chambers. As such, it is extremely difficult to estimate the total volume of gas inside a mound. And the team needed to know exactly that number to complete its study.

Measuring net emissions of methane into the atmosphere is "relatively easy", according to Dr. Nauter – just put a container on the mound and measure the amount of gas that comes out. In order to estimate the mound volumes, the team "developed a photogrammetric recording in which we took pictures from different angles and then calculated the 3D structure with software".

To see inside the mounds, Dr. Nauer appealed to the local medical community. He planned to do a scan of one of these mounds to get an estimate of his open volume. He assumed that the medical staff would "say no or [that there] was a waiting list of several months. "

"Instead, there was this radiographer, the first one I called, who just said," Oh cool, termites. I've always wanted to do that. Bring them. "

The last step was to determine the amount of methane that the mound bacteria could consume. They injected a known amount of methane and "tracer gas" (argon) into a mound, then extracted it and measured the amount of methane that had disappeared. On average, half of all methane was consumed by methanotrophs. This figure was calculated from 29 mounds made by three different termite species, says the team.

"Some mounds actually consumed methane in the atmosphere and others were massive sources, but on this scale, the percentage of methane consumed is very stable," says Dr. Nauer.

"The range was between 20 and 80%, but most mounds have an oxidation fraction of about 40 to 60%. So we think this 50% value is intrinsically integrated, because the system is kind of a buffer. If you have more production, you get more consumption. "

The team hopes to use its results to design new systems to control our own methane emissions. The real challenge "is to climb," admits Dr. Nauer.

Termites Mitigate Half Termite Methane Emissions Published in Newspaper Proceedings of the National Academy of Sciences.

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