The 14C natural abandance keep stable in the atmosphere, so will the acceleration of soil microorganism metabolism influnce the 14C natural abandance?
Dear Qiu,
C14 is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen.
The resulting 14C combines with atmospheric oxygen to form radioactive carbon dioxide, and then It goes to plant by photosinthesis, then to bateria and animals through the food chain.
After that , those gose to soil, there is no method to produce C14 in the soil significantly. But decay is taken place continuously.
But, metabolic activity of micro-organizm is a different story. It does not support to generate C14 in soil. Therefore, the acceleration of soil microorganism metabolism does not affect the 14C natural abandance in soil.
Piyal Aravinna
The abundance of 14C in the atmosphere is not constant. Measrements of 14C in tree rings is used to calibrate values in the past.
Variations of 14C are due to solar activity and changes to the Earth's magnetic field, but are also caused by return to the atmosphere of CO2 that has been buried in the past.
If the CO2, which the soil organisms are returning to the atmosphere, is composed of old carbon with low amounts of 14C then it will affect the atmospheric 14C.
Dear Bain,
thank you. What about the timely variation of C14 in Atmosphere for a longer period
Thank you
Piyal Aravinna
Hi Piyal,
In this paper, Denton, G. H., Broecker, W. S. and Alley, R. B. (2006) ‘The mystery interval 17.5 to 14.5 kyrs ago’, Pages News, vol. 14, no. 2, pp. 14–16 the problem of low 14C records during the last glacial termination is identified.
It has been suggested, Burke, A. and Robinson, L. F. (2012) ‘The Southern Ocean’s Role in Carbon Exchange During the Last Deglaciation’, Science, vol. 335, no. 6068, pp. 557–561 [Online]. DOI: 10.1126/science.1208163., that this was caused by the increase in atmospheric CO2 that occurred at that time originating from old carbon dioxide in the deep ocean.
See also Broecker, W. S. and Barker, S. (2007) ‘A 190‰ drop in atmosphere’s Δ 14 C during the “Mystery Interval”(17.5 to 14.5 kyr)’, Earth Planet. Sci. Lett, vol. 256, no. 1–2, pp. 90–99. Cheers, Alastair.
Hi Piyal,
I was not a coauthor of any of those papers, but they are related to my project
A New Inorganic Carbon System at: https://www.researchgate.net/project/A-New-Inorganic-Carbon-System
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