Chemical Force Spectroscopy Evidence Supporting the Layer-by-Layer Model of Organic Matter Binding to Iron (oxy)Hydroxide Mineral Surfaces

Alexander W. Chassé, Tsutomu Ohno, Steven R. Higgins, Aria Amirbahman, Nadir Yildirim, Thomas B. Parr

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

© 2015 American Chemical Society. The adsorption of dissolved organic matter (DOM) to metal (oxy)hydroxide mineral surfaces is a critical step for C sequestration in soils. Although equilibrium studies have described some of the factors controlling this process, the molecular-scale description of the adsorption process has been more limited. Chemical force spectroscopy revealed differing adhesion strengths of DOM extracted from three soils and a reference peat soil material to an iron (oxy)hydroxide mineral surface. The DOM was characterized using ultrahigh-resolution negative ion mode electrospray ionization Fourier Transform ion cyclotron resonance mass spectrometry. The results indicate that carboxyl-rich aromatic and N-containing aliphatic molecules of DOM are correlated with high adhesion forces. Increasing molecular mass was shown to decrease the adhesion force between the mineral surface and the DOM. Kendrick mass defect analysis suggests that mechanisms involving two carboxyl groups result in the most stable bond to the mineral surface. We conceptualize these results using a layer-by-layer "onion" model of organic matter stabilization on soil mineral surfaces.
Original languageEnglish (US)
Pages (from-to)9733-9741
Number of pages9
JournalEnvironmental Science & Technology
Volume49
Issue number16
DOIs
StatePublished - Aug 7 2015
Externally publishedYes

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