TY - JOUR
T1 - The impact of soil microorganisms on the global budget of δ18O in atmospheric CO2
AU - Wingate, Lisa
AU - Ogée, Jérôme
AU - Cuntz, Matthias
AU - Genty, Bernard
AU - Reiter, Ilja
AU - Seibt, Ulli
AU - Yakir, Dan
AU - Maseyk, Kadmiel
AU - Pendall, Elise G.
AU - Barbouri, Margaret M.
AU - Mortazavi, Behzad
AU - Burlett, Regis
AU - Peylin, Philippe
AU - Miller, John
AU - Mencuccini, Maurizio
AU - Shim, Jee H.
AU - Hunt, John
AU - Grace, John
PY - 2009
Y1 - 2009
N2 - Improved global estimates of terrestrial photosynthesis and respiration are critical for predicting the rate of change in atmospheric CO2. The oxygen isotopic composition of atmospheric CO2 can be used to estimate these fluxes because oxygen isotopic exchange between CO2 and water creates distinct isotopic flux signatures. The enzyme carbonic anhydrase (CA) is known to accelerate this exchange in leaves, but the possibility of CA activity in soils is commonly neglected. Here, we report widespread accelerated soil CO2 hydration. Exchange was 10-300 times faster than the uncatalyzed rate, consistent with typical population sizes for CAcontaining soil microorganisms. Including accelerated soil hydration in global model simulations modifies contributions from soil and foliage to the global CO18O budget and eliminates persistent discrepancies existing between model and atmospheric observations. This enhanced soil hydration also increases the differences between the isotopic signatures of photosynthesis and respiration, particularly in the tropics, increasing the precision of CO 2 gross fluxes obtained by using the δ18O of atmospheric CO2 by 50%.
AB - Improved global estimates of terrestrial photosynthesis and respiration are critical for predicting the rate of change in atmospheric CO2. The oxygen isotopic composition of atmospheric CO2 can be used to estimate these fluxes because oxygen isotopic exchange between CO2 and water creates distinct isotopic flux signatures. The enzyme carbonic anhydrase (CA) is known to accelerate this exchange in leaves, but the possibility of CA activity in soils is commonly neglected. Here, we report widespread accelerated soil CO2 hydration. Exchange was 10-300 times faster than the uncatalyzed rate, consistent with typical population sizes for CAcontaining soil microorganisms. Including accelerated soil hydration in global model simulations modifies contributions from soil and foliage to the global CO18O budget and eliminates persistent discrepancies existing between model and atmospheric observations. This enhanced soil hydration also increases the differences between the isotopic signatures of photosynthesis and respiration, particularly in the tropics, increasing the precision of CO 2 gross fluxes obtained by using the δ18O of atmospheric CO2 by 50%.
UR - http://handle.uws.edu.au:8081/1959.7/546772
U2 - 10.1073/pnas.0905210106
DO - 10.1073/pnas.0905210106
M3 - Article
SN - 0027-8424
VL - 106
SP - 22411
EP - 22415
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 52
ER -