Effect of temperature on the oxygen isotope composition of carbon dioxide prepared from carbonate minerals by reaction with polyphosphoric acid: An example of the rhombohedral CaCO3–MgCO3 group minerals

2010 ◽  
Vol 74 (22) ◽  
pp. 6406-6421 ◽  
Author(s):  
Stephen F. Crowley
2004 ◽  
Vol 136 (2) ◽  
pp. 3350-3363 ◽  
Author(s):  
Lucas A. Cernusak ◽  
Graham D. Farquhar ◽  
S. Chin Wong ◽  
Hilary Stuart-Williams

2013 ◽  
Vol 110 (44) ◽  
pp. 17680-17685 ◽  
Author(s):  
A. A. Wiegel ◽  
A. S. Cole ◽  
K. J. Hoag ◽  
E. L. Atlas ◽  
S. M. Schauffler ◽  
...  

SOIL ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 145-159
Author(s):  
Sam P. Jones ◽  
Aurore Kaisermann ◽  
Jérôme Ogée ◽  
Steven Wohl ◽  
Alexander W. Cheesman ◽  
...  

Abstract. The oxygen isotope composition of atmospheric carbon dioxide (CO2) is intimately linked to large-scale variations in the cycling of CO2 and water across the Earth's surface. Understanding the role the biosphere plays in modifying the oxygen isotope composition of atmospheric CO2 is particularly important as this isotopic tracer has the potential to constrain estimates of important processes such as gross primary production at large scales. However, constraining the atmospheric mass budget for the oxygen isotope composition of CO2 also requires that we understand better the contribution of soil communities and how they influence the rate of oxygen isotope exchange between soil water and CO2 (kiso) across a wide range of soil types and climatic zones. As the carbonic anhydrases (CAs) group of enzymes enhances the rate of CO2 hydration within the water-filled pore spaces of soils, it is important to develop understanding of how environmental drivers can impact kiso through changes in their activity. Here we estimate kiso and measure associated soil properties in laboratory incubation experiments using 44 soils sampled from sites across western Eurasia and north-eastern Australia. Observed values for kiso always exceeded theoretically derived uncatalysed rates, indicating a significant influence of CAs on the variability of kiso across the soils studied. We identify soil pH as the principal source of variation, with greater kiso under alkaline conditions suggesting that shifts in microbial community composition or intra–extra-cellular dissolved inorganic carbon gradients induce the expression of more or higher activity forms of CAs. We also show for the first time in soils that the presence of nitrate under naturally acidic conditions reduces kiso, potentially reflecting a direct or indirect inhibition of CAs. This effect appears to be supported by a supplementary ammonium nitrate fertilisation experiment conducted on a subset of the soils. Greater microbial biomass also increased kiso under a given set of chemical conditions, highlighting a putative link between CA expression and the abundance of soil microbes. These data provide the most extensive analysis of spatial variations in soil kiso to date and indicate the key soil trait datasets required to predict variations in kiso at large spatial scales, a necessary next step to constrain the important role of soil communities in the atmospheric mass budget of the oxygen isotope composition of CO2.


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