Jul 27, 2021 11:16 PM
A soil-science revolution upends plans to fight climate change
https://www.quantamagazine.org/a-soil-sc...-20210727/
INTRO: The hope was that the soil might save us. With civilization continuing to pump ever-increasing amounts of carbon dioxide into the atmosphere, perhaps plants — nature’s carbon scrubbers — might be able to package up some of that excess carbon and bury it underground for centuries or longer.
That hope has fueled increasingly ambitious climate change–mitigation plans. Researchers at the Salk Institute, for example, hope to bioengineer plants whose roots will churn out huge amounts of a carbon-rich, cork-like substance called suberin. Even after the plant dies, the thinking goes, the carbon in the suberin should stay buried for centuries. This Harnessing Plants Initiative is perhaps the brightest star in a crowded firmament of climate change solutions based on the brown stuff beneath our feet.
Such plans depend critically on the existence of large, stable, carbon-rich molecules that can last hundreds or thousands of years underground. Such molecules, collectively called humus, have long been a keystone of soil science; major agricultural practices and sophisticated climate models are built on them.
But over the past 10 years or so, soil science has undergone a quiet revolution, akin to what would happen if, in physics, relativity or quantum mechanics were overthrown. Except in this case, almost nobody has heard about it — including many who hope soils can rescue the climate. “There are a lot of people who are interested in sequestration who haven’t caught up yet,” said Margaret Torn, a soil scientist at Lawrence Berkeley National Laboratory.
A new generation of soil studies powered by modern microscopes and imaging technologies has revealed that whatever humus is, it is not the long-lasting substance scientists believed it to be. Soil researchers have concluded that even the largest, most complex molecules can be quickly devoured by soil’s abundant and voracious microbes. The magic molecule you can just stick in the soil and expect to stay there may not exist... (MORE - details)
Life in lava caves ignores food from surface, eats rock instead (geobiology)
https://www.insidescience.org/news/life-...ck-instead
EXCERPTS: . . . Lava caves, also known as lava tubes, are formed during volcanic eruptions when an outer crust of flowing lava hardens. The molten middle continues to drain away, leaving tunnels that can be several yards across. These tunnels may become buried under soil, but they often remain shallow enough that water can seep in, laden with food from the surface.
But researchers found that many bacteria growing on the walls of lava caves spurn the feast flowing over them. Instead, they produce their own energy from surrounding minerals or dissolved chemicals and build the molecules they need using carbon in the air or rock.
"This means that even in a very well-connected environment in the shallow subsurface, we still have evidence for life that is very independent from the surface living and thriving," said Matthew Selensky, a geobiologist...
[...] All living things need a source of energy to power their activities and a source of carbon to use as building material. Plants and other photosynthetic organisms get their energy from the sun ... Other creatures like humans and fungi get their energy and carbon by eating the remains of living things, essentially mooching off the work of photosynthesizers.
At least, that's how it usually works on Earth's sun-drenched surface. But there are other energy sources around, such as the chemical bonds of minerals and other inorganic material. Researchers have long known that some microbes use these chemical resources to produce energy in ways that don't rely on the sun... "Organisms that use other sources of energy besides solar energy exist pretty much everywhere on the planet," said Caitlin Casar...
[...] While researchers still don't know for sure what Mars contains in the way of caves, the red planet is thought to have many lava caves similar to (though likely larger than) those on Earth. ... the caves might contain water in the form of ice, as well as a variety of minerals that could serve as fuel for life. Such caves would also be protected from the toxic radiation and extreme temperature fluctuations of the surface, making them potential oases for living things now or in the past.
"The presence of active lithoautotrophy in these lava tube caves in California really shows that these types of environments can sustain a community based on lithoautotrophy, so we don't necessarily need abundant organic matter coming down from the surface," said Richard Leveille, an astrobiologist ... "It bolsters the idea that you could have microbes living in lava tube caves on Mars."
[...] Still, Martian lava caves may not be hospitable to living things today, Leveille cautioned. Even in ice, organisms need fissures or pockets of liquid water to live in an active state, and it's possible that Martian lava caves are just too cold and dry.
Indeed, Blank doesn't expect that a mission to Martian lava caves would discover living organisms. But the same features that could have protected cave life in Mars's distant past might have preserved evidence of that life until the present day. Microbes often change how minerals precipitate out of water, and researchers could detect those changes in the layers of silica and other minerals on the cave walls... (MORE - details)
https://www.quantamagazine.org/a-soil-sc...-20210727/
INTRO: The hope was that the soil might save us. With civilization continuing to pump ever-increasing amounts of carbon dioxide into the atmosphere, perhaps plants — nature’s carbon scrubbers — might be able to package up some of that excess carbon and bury it underground for centuries or longer.
That hope has fueled increasingly ambitious climate change–mitigation plans. Researchers at the Salk Institute, for example, hope to bioengineer plants whose roots will churn out huge amounts of a carbon-rich, cork-like substance called suberin. Even after the plant dies, the thinking goes, the carbon in the suberin should stay buried for centuries. This Harnessing Plants Initiative is perhaps the brightest star in a crowded firmament of climate change solutions based on the brown stuff beneath our feet.
Such plans depend critically on the existence of large, stable, carbon-rich molecules that can last hundreds or thousands of years underground. Such molecules, collectively called humus, have long been a keystone of soil science; major agricultural practices and sophisticated climate models are built on them.
But over the past 10 years or so, soil science has undergone a quiet revolution, akin to what would happen if, in physics, relativity or quantum mechanics were overthrown. Except in this case, almost nobody has heard about it — including many who hope soils can rescue the climate. “There are a lot of people who are interested in sequestration who haven’t caught up yet,” said Margaret Torn, a soil scientist at Lawrence Berkeley National Laboratory.
A new generation of soil studies powered by modern microscopes and imaging technologies has revealed that whatever humus is, it is not the long-lasting substance scientists believed it to be. Soil researchers have concluded that even the largest, most complex molecules can be quickly devoured by soil’s abundant and voracious microbes. The magic molecule you can just stick in the soil and expect to stay there may not exist... (MORE - details)
Life in lava caves ignores food from surface, eats rock instead (geobiology)
https://www.insidescience.org/news/life-...ck-instead
EXCERPTS: . . . Lava caves, also known as lava tubes, are formed during volcanic eruptions when an outer crust of flowing lava hardens. The molten middle continues to drain away, leaving tunnels that can be several yards across. These tunnels may become buried under soil, but they often remain shallow enough that water can seep in, laden with food from the surface.
But researchers found that many bacteria growing on the walls of lava caves spurn the feast flowing over them. Instead, they produce their own energy from surrounding minerals or dissolved chemicals and build the molecules they need using carbon in the air or rock.
"This means that even in a very well-connected environment in the shallow subsurface, we still have evidence for life that is very independent from the surface living and thriving," said Matthew Selensky, a geobiologist...
[...] All living things need a source of energy to power their activities and a source of carbon to use as building material. Plants and other photosynthetic organisms get their energy from the sun ... Other creatures like humans and fungi get their energy and carbon by eating the remains of living things, essentially mooching off the work of photosynthesizers.
At least, that's how it usually works on Earth's sun-drenched surface. But there are other energy sources around, such as the chemical bonds of minerals and other inorganic material. Researchers have long known that some microbes use these chemical resources to produce energy in ways that don't rely on the sun... "Organisms that use other sources of energy besides solar energy exist pretty much everywhere on the planet," said Caitlin Casar...
[...] While researchers still don't know for sure what Mars contains in the way of caves, the red planet is thought to have many lava caves similar to (though likely larger than) those on Earth. ... the caves might contain water in the form of ice, as well as a variety of minerals that could serve as fuel for life. Such caves would also be protected from the toxic radiation and extreme temperature fluctuations of the surface, making them potential oases for living things now or in the past.
"The presence of active lithoautotrophy in these lava tube caves in California really shows that these types of environments can sustain a community based on lithoautotrophy, so we don't necessarily need abundant organic matter coming down from the surface," said Richard Leveille, an astrobiologist ... "It bolsters the idea that you could have microbes living in lava tube caves on Mars."
[...] Still, Martian lava caves may not be hospitable to living things today, Leveille cautioned. Even in ice, organisms need fissures or pockets of liquid water to live in an active state, and it's possible that Martian lava caves are just too cold and dry.
Indeed, Blank doesn't expect that a mission to Martian lava caves would discover living organisms. But the same features that could have protected cave life in Mars's distant past might have preserved evidence of that life until the present day. Microbes often change how minerals precipitate out of water, and researchers could detect those changes in the layers of silica and other minerals on the cave walls... (MORE - details)