In the Arctic, spring snowmelt triggers fresh CO2 production

July 01, 2020

Studies have shown the Arctic is warming roughly twice as fast as the rest of the world, and its soil holds twice the amount of carbon dioxide as the atmosphere. New research from San Diego State University finds that water from spring snowmelt infiltrates the soil and triggers fresh carbon dioxide production at higher rates than previously assumed.

This is in addition to trapped carbon escaping from the soil, which means an acceleration in warming that is not quite accounted for in current measurement techniques.

SDSU post-doctoral fellow Kyle Arndt and ecosystem ecologist Donatella Zona spent several years assessing the situation on the ground in Utqiagvik (formerly Barrow), Alaska and analyzing their findings once they returned to San Diego.

The cold season is an essential component of the annual carbon balance, and it was assumed to have a negligible impact on carbon production.

By analyzing soil core samples, what they found was that it wasn't just trapped greenhouse gases that were escaping but also likely increasing fresh production of carbon during the spring thaw.

Published June 30 in Global Change Biology, their
"Earlier we didn't have this data, but now that we do, we are seeing that these ecosystems are rapidly warming," Arndt said. "Many models already predict the Arctic will turn into a CO2 source, but they may be underestimating the size of the source if this spring process is not taken into account."

Arndt, first author of the paper, began visiting Utqiagvik in summer 2016 to maintain equipment set up by SDSU ecologist Walter Oechel, who has been working for nearly 40 years in these Arctic sites.

Using eddy covariance, a technique to measure carbon dioxide movement between the soil and atmosphere as well as ground and air temperatures, ground heat flux and snow depth, Arndt measured fluxes.

Heat flux is the energy transferred per unit of surface area for a given period of time, and it's challenging to collect it during the freeze. Arndt "came up with the idea of measuring it during spring snow melt, building on the need to fill a gap in data on the cold season Arctic heat fluxes," Zona said.

Arndt also worked with SDSU microbiologist David Lipson who collected soil core samples, which helped him and Zona understand the physical properties of the soil during the spring and fall season.

Arndt ascertained that fresh CO2 production was happening when "we found air pockets in the middle of the soil core that allowed for the melted snow to rush in. The snowmelt is rich in oxygen which helps with the production of carbon dioxide."

Iron is one of the many minerals soil contains. Their analysis showed the iron was completely oxidized, which can only happen if fresh oxygen in the soil bonds with and oxidizes the iron. The researchers found a steady rise in CO? emissions during this thawing period further suggesting the occurrence of production at this time.

Simpler models of data analysis may miss the rapid warming that happens due to snowmelt, when there's a rapid introduction of oxygen leading to the warming.

"There's a lot more going on in the soil than we previously thought," Arndt said. "Nature is efficient in that it breaks down lighter compounds preferentially to heavier ones, creating unique isotope signatures, kind of like fingerprints. By looking at isotopes, we can tell how long the compounds have been there and the source of the carbon emitted."

Arndt and Zona are planning to focus on isotopic analysis next, to reconstruct the age of the compounds in the samples, and the longer scale implications of these results.

"We will look for long-term trends in carbon dioxide release and how the heat fluxes have been changing over the last decade," Zona said.
This research was funded by grants from the National Science Foundation (NSF), NASA CARVE and ABoVE programs, National Oceanic and Atmospheric Administration CREST, the Horizon 2020 INTAROS, and the NERC UAMS projects.

San Diego State University

Related Carbon Articles from Brightsurf:

The biggest trees capture the most carbon: Large trees dominate carbon storage in forests
A recent study examining carbon storage in Pacific Northwest forests demonstrated that although large-diameter trees (21 inches) only comprised 3% of total stems, they accounted for 42% of the total aboveground carbon storage.

Carbon storage from the lab
Researchers at the University of Freiburg established the world's largest collection of moss species for the peat industry and science

Carbon-carbon covalent bonds far more flexible than presumed
A Hokkaido University research group has successfully demonstrated that carbon-carbon (C-C) covalent bonds expand and contract flexibly in response to light and heat.

Metal wires of carbon complete toolbox for carbon-based computers
Carbon-based computers have the potential to be a lot faster and much more energy efficient than silicon-based computers, but 2D graphene and carbon nanotubes have proved challenging to turn into the elements needed to construct transistor circuits.

Cascades with carbon dioxide
Carbon dioxide (CO(2)) is not just an undesirable greenhouse gas, it is also an interesting source of raw materials that are valuable and can be recycled sustainably.

Two-dimensional carbon networks
Lithium-ion batteries usually contain graphitic carbons as anode materials. Scientists have investigated the carbonic nanoweb graphdiyne as a novel two-dimensional carbon network for its suitability in battery applications.

Can wood construction transform cities from carbon source to carbon vault?
A new study by researchers and architects at Yale and the Potsdam Institute for Climate Impact Research predicts that a transition to timber-based wood products in the construction of new housing, buildings, and infrastructure would not only offset enormous amounts of carbon emissions related to concrete and steel production -- it could turn the world's cities into a vast carbon sink.

Investigation of oceanic 'black carbon' uncovers mystery in global carbon cycle
An unexpected finding published today in Nature Communications challenges a long-held assumption about the origin of oceanic black coal, and introduces a tantalizing new mystery: If oceanic black carbon is significantly different from the black carbon found in rivers, where did it come from?

First fully rechargeable carbon dioxide battery with carbon neutrality
Researchers at the University of Illinois at Chicago are the first to show that lithium-carbon dioxide batteries can be designed to operate in a fully rechargeable manner, and they have successfully tested a lithium-carbon dioxide battery prototype running up to 500 consecutive cycles of charge/recharge processes.

How and when was carbon distributed in the Earth?
A magma ocean existing during the core formation is thought to have been highly depleted in carbon due to its high-siderophile (iron loving) behavior.

Read More: Carbon News and Carbon Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to