Spatial Arrangement of Organic Compounds on a Model Mineral Surface: Implications for Soil Organic Matter Stabilization

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• 作者：Loukas Petridis ; Haile Ambaye ; Sindhu Jagadamma ; S. Michael Kilbey ; II ; Bradley S. Lokitz ; Valeria Lauter ; Melanie A. Mayes
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：January 7, 2014
• 年：2014
• 卷：48
• 期：1
• 页码：79-84
• 全文大小：265K
• ISSN：1520-5851

文摘

The complexity of the mineral鈥搊rganic 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.