See more from this Session: Symposium--Mineral-Organic Interactions Across Time and Space: I & II
Batch sorption experiments were performed using several soils to generate organo-mineral complexes with increasing C loadings by mixing low-C subsoil samples with increasing concentrations (~50-500 mg C L-1) of dissolved organic matter (DOM) generated from leaf litter leachate. The DOM and minerals were allowed to interact for 24h at 20°C while mixed on an orbital shaker. Degradation of the DOM during the experiment was determined using zero-mineral blank samples. The resultant organo-mineral complexes were subsequently tested for variations in SOM quality as a function of C loading using C and N isotopic ratios (δ13C and δ15N), specific respiration (µg CO2-C per g sample-C) during short-term laboratory incubations, and thermal analysis.
Preliminary results show that 2.1-34.8% (mean = 18.3%) of initial DOC was sorbed, resulting in estimated C-loadings between 0.15-2.45 mg C m-2. The expected outcome of subsequent analyses is that as a soil approaches its C saturation limit (i.e., maximal C loading), SOM becomes increasingly decomposable.