title: Characterization of hydrophobic soils: a novel approach using mid-infrared photoacoustic spectroscopy.
abstract: Previous research has produced conclusive evidence to show that soil hydrophobicity is affected by soil organic matter (SOM) and soil water content (WC). Soil hydrophobicity that responds to WC is a unique form of hydrophobicity called reversible hydrophobicity. The mechanistic processes by which water and SOM interact continue to be a subject of investigation. This article presents a novel application of photoacoustic Fourier transform infrared spectroscopy (FT-IR) for the investigation of reversibly hydrophobic soils. Photoacoustic FT-IR data show that, in response to hydration, surface molecules on wetted soil particles interacted differently with mid-infrared radiation than surface molecules present on air-dried soil. This can be interpreted as an effect of the reorienting of amphiphilic molecules in response to hydration-driven entropic processes. These results suggest that the photoacoustic FT-IR method can be used to elucidate how SOM and water interact at the molecular scale to drive soil hydrophobicity.
authors.affiliation: Oregon State University, Department of Crop and Soil Science, 3017 ALS, Corvallis, Oregon 97333 USA.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Woolverton
authors.forename: Maria Ines
authors.initials: MI
authors.lastname: Dragila