Scientists at Caltech and USC have discovered a way to speed up the slow part of the chemical reaction that ultimately helps the earth to safely lock away, or sequester, carbon dioxide into the ocean. Simply adding a common enzyme to the mix, the researchers have found, can make that rate-limiting part of the process go 500 times faster.
On paper, the reaction is fairly straightforward: Water plus carbon dioxide plus calcium carbonate equals dissolved calcium and bicarbonate ions in water. In practice, it is complex. “Somehow, calcium carbonate decides to spontaneously slice itself in half. But what is the actual chemical path that reaction takes?” Adkins says.
Studying the process with a secondary ion mass spectrometer (which analyzes the surface of a solid by bombarding it with a beam of ions) and a cavity ringdown spectrometer (which analyzes the 13C/12C ratio in solution), Subhas discovered that the slow part of the reaction is the conversion of carbon dioxide and water to carbonic acid.
“This reaction has been overlooked,” Subhas says. “The slow step is making and breaking carbon-oxygen bonds. They don’t like to break; they’re stable forms.”
Armed with this knowledge, the team added the enzyme carbonic anhydrase — which helps maintain the pH balance of blood in humans and other animals — and were able to speed up the reaction by orders of magnitude.
Key to speeding up carbon sequestration discovered | EurekAlert! Science News
That makes me wonder about the chemical limitation of carbon sequestration in soils.
Bacterial cells in carbon-rich media (purple and blue) grow twice as big as those in carbon-poor media (green). New research shows they can grow big, however, only if they can make fats with the carbon.
Fat (lipids) limits how big bacterial cells can be. “If you prevent cells from making fat, they’re smaller, and if you give them extra fat or allow them to make more fat, they get bigger,” said Levin, professor of biology in Arts & Sciences. “Fat makes cells fat.”
“If we hit the cells with an antibiotic that targets fatty-acid synthesis, we really saw a significant drop in cell size” Vadia said.
Also, by turning up FadR, a transcription factor that activates expression of the fatty-acid synthesis genes, the cells got bigger.
“It doesn’t seem to matter what the lipids are, really,” Levin said, “provided you have enough of them. We found we could give the cells oleic acid, a fat found in avocados and olive oil, to supplement diminished fatty-acid synthesis and as long as the added fatty acid got into the membrane, the cells could recover.”
A little place for my stuff | EurekAlert! Science News
Fatty Acid Availability Sets Cell Envelope Capacity and Dictates Microbial Cell Size: Current Biology
Hydrogenation: transform liquid oil into solid fat
Olive Oil Did WHAT to my Triglycerides??!!?? (Pt 2)
Storage of carbon in the stationary phase.
Signature metabolisms that change with growth phase.
In regions with more rainfall historically, soil microbes were found to respire twice as much carbon to the atmosphere as microbes from drier regions. Scientists determined that this was because the microbes responded differently to change: Those from the wettest areas were four times as sensitive to shifts in moisture as their counterparts from the driest areas.
“Because microbes are small and enormously diverse, we have this idea that when the environment changes, microbes can rapidly move around or shift local abundances to track that environmental change,” Hawkes said. “We discovered, however, that soil microbes and their functions are highly resistant to change. Resistance to environmental change matters because it means that previous local conditions will constrain how ecosystems function when faced with a shift in climate.”
Historical rainfall levels are significant in carbon emissions from soil
A new study titled Is the rate of mineralization of soil organic carbon under microbiological control? suggests that:
- the rate limiting step in SOC mineralization is abiotic (physical rather than biological).
- that mineralization of SOC may be a two-stage process: firstly, non-bioavailable forms are converted abiologically to bioavailable forms, which, only then, undergo a second process, biological mineralization.
I’ll speculate and say that mineralization is perhaps limited by dissolved organic matter in the form of complex carbon structures that are produced by weathering, oxidation, and detritivores that break apart plant litter. Liquid compounds that tend to be lost when composting.
Compounds that are probably why wet climates and seagrasses sequester the most carbon.
Why drying and wetting of these compounds leads to CO2-Bursts.
Compounds we should be trying to keep in the soil profile doing good, and not in aquifers or waterways creating algal blooms, like we really need to with this recently discovered underground molten lake the size of Mexico!
That depending on the complexity of the carbon molecule as it gets passed down the soil carbon continuum food web it may be more than a two-stage process, with more than one in both the physical and biological realms based upon chemical energy and chemisorption of the carbon compounds.
*shrugs* Just my guess, I suck at chemistry.
Add 1.5% biochar to a 3.5% (0-100mm sampled) soil organic carbon soil, wait 9 years and it begins to positively prime. Clearly they didn’t add enough to reach a tipping point faster, or depending on your perspective and availability, adding biochar to low carbon soils is a long-term investment. I assume it was surface applied as the study is paywalled.
Paywalled: Biochar built soil carbon over a decade by stabilizing rhizodeposits : Nature Climate Change : Nature Research
The ocean sequesters massive amounts of carbon in the form of “dissolved organic matter,” and new research explains how an ancient group of cells in the dark ocean wrings the last bit of energy from carbon molecules resistant to breakdown.
A look at genomes from SAR202 bacterioplankton found oxidative enzymes and other important families of enzymes that indicate SAR202 may facilitate the last stages of breakdown before the dissolved oxygen matter, or DOM, reaches a “refractory” state that fends off further decomposition.
Zach Landry, an OSU graduate student and first author of the study, named SAR202 “Monstromaria” from the Latin term for “sea monster.”
Study illuminates fate of marine carbon in last steps toward sequestration| Oregon State University
SAR202 Genomes from the Dark Ocean Predict Pathways for the Oxidation of Recalcitrant Dissolved Organic Matter
Scientists begin to unlock secrets of deep ocean color from organic matter | UMCES
For the first time, researchers have shown that cultured picocyanobacteria, Synechococcus and Prochlorococcus, found in the open ocean release fluorescent components that closely match these typical fluorescent signals found in oceanic environments.
“Two genus of picocyanobacteria – Synechococus and Prochlorocccos – are the most abundant carbon fixers in the ocean.” said Chen. His lab maintains a collection of marine cyanobacteria and cyanoviruses. Some of these isolates were used in this study.
“When you sail on the blue ocean, a lot of picocyanbacteria are working there,” said Gonsior.” They turn carbon dioxide into organic carbon and are likely responsible for some of the deep ocean color coming from organic matter.”
Now this is interesting:
“the rhizosphere priming effect was positively correlated with aboveground plant biomass, but surprisingly not with root biomass“
- Grow diverse aboveground biomass
- Chop and drop
- Mulcho profit!
In a meta-analysis of 31 studies, researches show that the rhizosphere enhances soil organic carbon mineralization by 59%[*].
That woody species are best, then grass, then crops.
[Me: *So long as it’s fed from the above ground biomass litter.]
Sounds like C:Nhoosing Your Mulch? Think of the Fungi to me, and photosynthesise as much as you can be!
Don’t forget plant and mulch diversity in this mix, as Plant litter diversity increases microbial abundance, fungal diversity, and carbon and nitrogen cycling.
Another interesting study today suggests that soil fungal community is mainly influenced by plant community composition, distance between communities, and rainfall.
So go diverse and you can’t really lose.
Diverse ecosystems in connected communities.