Thursday, August 6, 2009 - 2:10 PMOOS 44-3: Using 13C-NMR and radiocarbon to determine mechanisms of soil organic matter stabilization in dynamic landscapes
Asmeret Asefaw Berhe, University of California, Merced
1) Background/Question/Methods ,
Lateral redistribution of topsoil imposes significant control on storage, chemical composition, and turnover rate of soil organic matter (SOM) in hillslope environments. The effect of such physical landscape processes is often neglected in biogeochemical studies despite the fact that a significant part of the global land area is made up of hillslope ecosystems that are dynamic over short and long timescales. Here we use a combination of nuclear magnetic resonance (CPMAS 13C-NMR) and accelerated mass spectrometry (14C) to semiquantitatively characterize the molecular architecture of soil organic matter and its turnover rates at different landform positions along toposequence.
2) Results/Conclusions
When combined with fractionation and extraction methods, these spectroscopic methods reveal that even short-scale lateral redistribution of topsoil by soil erosion can have significant implication for not just overall stability, but also specific stabilization mechanisms of SOM.
Lateral redistribution of topsoil imposes significant control on storage, chemical composition, and turnover rate of soil organic matter (SOM) in hillslope environments. The effect of such physical landscape processes is often neglected in biogeochemical studies despite the fact that a significant part of the global land area is made up of hillslope ecosystems that are dynamic over short and long timescales. Here we use a combination of nuclear magnetic resonance (CPMAS 13C-NMR) and accelerated mass spectrometry (14C) to semiquantitatively characterize the molecular architecture of soil organic matter and its turnover rates at different landform positions along toposequence.
2) Results/Conclusions
When combined with fractionation and extraction methods, these spectroscopic methods reveal that even short-scale lateral redistribution of topsoil by soil erosion can have significant implication for not just overall stability, but also specific stabilization mechanisms of SOM.