title: Spatial arrangement of organic compounds on a model mineral surface: implications for soil organic matter stabilization.
abstract: The complexity of the mineral-organic carbon interface may influence the extent of stabilization of organic carbon compounds in soils, which is important for global climate futures. The nanoscale structure of a model interface was examined here by depositing films of organic carbon compounds of contrasting chemical character, hydrophilic glucose and amphiphilic stearic acid, onto a soil mineral analogue (Al2O3). Neutron reflectometry, a technique which provides depth-sensitive insight into the organization of the thin films, indicates that glucose molecules reside in a layer between Al2O3 and stearic acid, a result that was verified by water contact angle measurements. Molecular dynamics simulations reveal the thermodynamic driving force behind glucose partitioning on the mineral interface: The entropic penalty of confining the less mobile glucose on the mineral surface is lower than for stearic acid. The fundamental information obtained here helps rationalize how complex arrangements of organic carbon on soil mineral surfaces may arise.
authors: Center for Molecular Biophysics, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
authors: Loukas
authors: L
authors: Petridis
authors: Haile
authors: H
authors: Ambaye
authors: Sindhu
authors: S
authors: Jagadamma
authors: S Michael
authors: SM
authors: Kilbey
authors: Bradley S
authors: BS
authors: Lokitz
authors: Valeria
authors: V
authors: Lauter
authors: Melanie A
authors: MA
authors: Mayes
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D012987:Soil / Q000737:chemistry*; D013229:Stearic Acids / Q000737:chemistry
chemical_list: D012987:Soil; D013229:Stearic Acids; C031183:stearic acid; D002244:Carbon; D005947:Glucose; D000537:Aluminum Oxide