title: Chemical Force Spectroscopy Evidence Supporting the Layer-by-Layer Model of Organic Matter Binding to Iron (oxy)Hydroxide Mineral Surfaces.
abstract: 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.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Chassé
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Ohno
authors.affiliation: ∥Department of Chemistry, Wright State University, Dayton, Ohio 45435, United States.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Higgins
authors.forename: Aria
authors.initials: A
authors.lastname: Amirbahman
authors.forename: Nadir
authors.initials: N
authors.lastname: Yildirim
authors.affiliation: ¶Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Parr
mesh_terms: D000327:Adsorption; D006878:Hydroxides / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D013058:Mass Spectrometry; D018625:Microscopy, Atomic Force; D008903:Minerals / Q000737:chemistry*; D008956:Models, Chemical; D008970:Molecular Weight; D009930:Organic Chemicals / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D006878:Hydroxides; D008903:Minerals; D009930:Organic Chemicals; D007501:Iron