Clay minerals are important natural adsorbents of soil organic matter (SOM) and therefore natural modulators of soil-atmospheric carbon fluxes. Although such effects have been reported, little is known about the spatial distribution of organic matter (OM) on soil mineral surfaces and even less is known about the effect of microstructural changes on their OM loading capacity. Here, we employ FT-IR spectroscopy as a primary analytical technique to investigate the adsorption of soil microbial biomass (a primary source of SOM) onto montmorillonite clay mineral subjected to different durations of acid hydrolysis. After hydrolysis, the most prominent change to the mineral structure was the dissolution of octahedral cations over time. Microbial interactions with acid treated clay have also been confirmed; however, the relative concentration of microbial-derived components on clay surfaces, in particular lipids, decreased with increasing acid degradation time. Therefore, we speculate that this decrease is due to spatial co-variation of microbial derived OM with octahedral cations as well as an increase in the hydrophilicity of the mineral surface by acid treatment as a function of time.

Effects of microstructural changes on the organic matter loading capacity of montmorillonite

246th National Meeting (2013)

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