Combined proton NMR wideline and NMR relaxometry to study SOM-water interactions of cation-treated soils
Combined proton NMR wideline and NMR relaxometry to study SOM-water interactions of cation-treated soils
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结合质子 NMR 宽线和 NMR 弛豫测量来研究阳离子处理土壤的 SOM-水相互作用
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发表时间：
2013
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通讯作者：
J. Bachmann
中科院分区：
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作者：
G. Schaumann;D. Diehl;M. Bertmer;A. Jaeger;P. Conte;G. Alonzo;J. Bachmann
摘要针对多价阳离子对土壤有机质基质和表面的影响，我们用NaCl、CaCl 2和AlCl 3溶液处理泥炭和土壤样品。用低场1H-NMR-弛豫测定法（20 MHz）和1H宽谱线NMR光谱（400 MHz）表征水结合，并与接触角进行比较。从1H宽线，我们区分移动的水和水分子桥（WaMB）参与的水。SOM官能团之间的大部分阳离子桥（CaB）与WaMB相关。出乎意料的是，1H NMR弛豫速率表明，在含铝泥炭的交联不强于钙。移动的水和WaMB水的润湿性和1H NMR弛豫时间的上下文中的百分比之间的关系证实，润湿性控制周围的土壤颗粒的水膜。Wedding是由WaMB-CaB协会固定在SOM内部的亲水性官能团控制。这可能导致严重的防水性。随着CaB-WaMB协会中功能组的参与增加，western降低。结果表明，CaB和WaMB的相关性的动态的土壤地球化学和水文过程在现场条件下，只有百分之几的有机物质可以影响整个3相生态系统的物理，化学和生物功能。
Abstract Focusing on the idea that multivalent cations affect SOM matrix and surface, we treated peat and soil samples by solutions of NaCl, CaCl2 or AlCl3. Water binding was characterized with low field 1H-NMR-relaxometry (20 MHz) and 1H wideline NMR spectroscopy (400 MHz) and compared to contact angles. From 1H wideline, we distinguished mobile water and water involved in water molecule bridges (WaMB). Large part of cation bridges (CaB) between SOM functional groups are associated with WaMB. Unexpectedly, 1H NMRrelaxometry relaxation rates suggest that cross-linking in the Al-containing peat is not stronger than that by Ca. The relation between percentage of mobile water and WaMB water in the context of wettability and 1H NMR relaxation times confirms that wettability controls the water film surrounding soil particles. Wettability is controlled by WaMB-CaB associations fixing hydrophilic functional groups in the SOM interior. This can lead to severe water repellency. Wettability decreases with increasing involvement of functional groups in CaB-WaMB associations. The results demonstrate the relevance of CaB and WaMB for the dynamics of biogeochemical and hydrological processes under field conditions, as only a few percent of organic matter can affect the physical, chemical, and biological functioning of the entire 3-phase ecosystem.