Redwood Reader

124. Off-Site Carbon Sequestration by Forests


Would that this study focused on or included glomalin. What is Dissolved inorganic carbon anyway? The glomalin research talks of glomalin and humic acid. Some CO2 evists in the soil as decaying glomalin or as a product of respiration of organisms. However, the majority of production goes into glomalin which has high repellency properties and is relatively easily destroyed by the forces that provide transport. Runoff may carry some percent of this as dissolved carbon but it seems likely to be a small percentage of the original soil deposit. The referred to wetland articles likewise make no inclusion for repellant carbon products accumulated by biodeposition. This has them thinking large amounts of carbon are going out to sea rather than conditioning the soil where it is.

Reference
Karberg, N.J., Pregitzer, K.S., King, J.S., Friend, A.L. and Wood, J.R. 2005. Soil carbon dioxide partial pressure and dissolved inorganic carbonate chemistry under elevated carbon dioxide and ozone. Oecologia 142: 296-306.
What was done
In the words of the authors, "free air CO2 and O3 enrichment (FACE) technology was used at the Aspen FACE project in Rhinelander, Wisconsin [USA] to understand how elevated atmospheric CO2 and O3 interact to alter pCO2 and DIC [dissolved inorganic carbon] concentrations in the soil." The experimental setting consisted of three blocks of four treatments - control, elevated CO2, elevated O3, and elevated CO2 + O3 - where ambient CO2 was 360 ppm, elevated CO2 was 542 ppm, ambient O3 was 33 ppb, and elevated O3 was 49 ppb, and where half of each FACE ring was planted with trembling aspen, a quarter with a 1:1 mix of trembling aspen and paper birch, and a quarter with a mix of trembling aspen and sugar maple. The CO2 and O3 treatments were applied over the 2002 growing season, which ran from 28 May to 11 October, during which period bi-weekly samples of the soil air and solution were retrieved from depths of 15, 30 and 125 cm for various chemical analyses in the laboratory.

These Face experiments are the basis of much of CO2 Science’s work. They also make excellent way to nurture seedlings through difficult early stages in difficult country, such as on slides and river bars. They also are the way to do glomalin studies but I’d like to see extended timelines into decades, and depth to the 15 foot or deeper, in permanent forest installations. But then again, maybe ground radar readings of soil moisture can save us time and trouble.
What was learned

Karberg et al. report that "measured concentrations of soil CO2 and calculated concentrations of DIC increased over the growing season by 14 and 22%, respectively, under elevated atmospheric CO2 and were unaffected by elevated tropospheric O3." In addition, they say "the increased concentration of DIC altered inorganic carbonate chemistry by increasing system total alkalinity by 210%, likely due to enhanced chemical weathering [of primary minerals]," and they note that a mixing model they employed "showed that new atmospheric CO2 accounted for approximately 90% of the C leaving the system as DIC."

“Calculatyed concentrations of DIC show these are estimates of theoretical products rather than measured amounts of known products. After that it is a matter of speculation. Perhaps this is the humic acid fraction of total production, but generally these are merely confusing the issue. Increased biological activity could account for a shortage of H+ ions in the soil, giving it a high pH. This may be a general finding and so very helpful in understanding what is going on in the soil.

What it means
The Michigan scientists state that the CO2-induced increase in soil solution DIC, which ultimately makes its way to rivers that reach oceans, "represents a potential long-lived sequestration reservoir in deep ocean sediments," noting further that it suggests that "aggrading forest ecosystems may be used to capture and sequester atmospheric CO2 through inorganic processes," which have the potential to transfer it to the bottoms of faraway seas. See also, in this regard, our reviews of the studies of Raymond and Cole (2003) and Wang and Cai (2004). And, of course, it is important to note that this phenomenon can be significantly enhanced by increases in the air's CO2 concentration.
References
Raymond, P.A. and Cole, J.J. 2003. Increase in the export of alkalinity from North America's largest river. Science 301: 88-91.
Wang, Z.A. and Cai, W.-J. 2004. Carbon dioxide degassing and inorganic carbon export from a marsh-dominated estuary (the Duplin River): A marsh CO2 pump. Limnology and Oceanography 49: 341-354.
Reviewed 27 April 2005

Aaarrrggggghhhhh! How and why do they jump from the hillside to the sea floor? Sure sediment does that but we know glomalin reverts to CO2, and if you dissolve that you get acid, not base. We are looking for the mechanism that allows CO2 to create water storage and tilth in the soil as the basis of agriculure and forestry, and prevent sedimentation that is dasmaging rivers and fisheries. Carbon depostion will be a fraction of sediment delivery from the same original source because most of the glomalin has reverted. It seems unlikely carbon can be transported without lowering its pH, and that dissolved CO2 would accumulate in sediments since it is already mobile. Some glomalin goes into the water every year in various scour and slide events but most sediment delivery has much of its glomalin component destroyed. As they note, forest aggradations are tying up lots of carbon. Call it inorganic if you like, but it is manufactured by fungi and is an essential component of terrestrial precipitation capture. I like bio-deposition, like ferro-bacteria or chalk or coal. One other thing to think about here- submarine canyon loading and undersea landslides caused ny sediment buildup.