Interactions between cations and water molecule bridges in soil organic matter
Interactions between cations and water molecule bridges in soil organic matter
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DOI：
10.1007/s11368-013-0746-7
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发表时间：
2013-07
影响因子：
3.6
通讯作者：
G. Schaumann;Daniela Gildemeister;Yamuna Kunhi Mouvenchery;S. Spielvogel;D. Diehl
中科院分区：
文献类型：
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作者：
G. Schaumann;Daniela Gildemeister;Yamuna Kunhi Mouvenchery;S. Spielvogel;D. Diehl
土壤有机质（SOM）、阳离子和水分子桥（WaMB）之间的交联会影响土壤有机质（SOM）的养分释放、土壤润湿性、水结合和基质刚性。并不是所有阳离子对SOM的影响都可以用目前公认的多价阳离子通过直接阳离子桥（CaB）交联有机质片段的观点来解释。目的是了解这些相互作用及其对SOM基质刚度和润湿性的影响。材料和方法我们利用阳离子交换树脂对两种泥炭和有机表面层（OSL）的阳离子组成进行了改性，去除阳离子，并用Na+， Ca2+或Al3+溶液使样品富含阳离子。采用差示扫描量热法，在治疗后4周和8周通过WaMB转变温度t *测定SOM基质刚度。通过固滴接触角（CA）测定润湿性。结果与讨论阳离子去除效果取决于阳离子交换容量和初始阳离子含量。在OSL中加入阳离子增加了t *。这种效应随着阳离子负载和价的增加而增加，t *与CA相关。经典交联既不能解释CA处理样品比al处理样品更高的非均相基质，也不能解释不同阳离子和浓度的老化诱导的ofT*收敛。后者可能是由于SOM中CaB和WaMB之间的相互作用。结论CaB与WaMB的关联在SOM中进化缓慢，形成一个超分子网络。这些动态关联可以固定诱导拒水的分子排列，并增加从老化土壤中释放和吸收水分和养分的动力学障碍。
PurposeNutrient release, soil wettability, water binding, and matrix rigidity of soil organic matter (SOM) can be affected by cross-links between segments of SOM, cations, and water molecule bridges (WaMB). Not all cation effects on SOM can be explained with the currently accepted idea that multivalent cations cross-link organic matter segments via direct cation bridges (CaB). The objective was to understand these interactions and their effect on SOM matrix rigidity and wettability.Materials and methodsWe modified cation composition of two peats and an organic surface layer (OSL) using cation exchange resin to remove cations and solutions of Na+, Ca2+, or Al3+to enrich samples with cations. SOM matrix rigidity was determined at 4 and >8 weeks after treatment via the WaMB transition temperatureT*, using differential scanning calorimetry. Wettability was measured via sessile drop contact angle (CA).Results and discussionThe effect of cation removal onT* depended on cation exchange capacity and initial cation content. Cation addition to OSL increasedT*. This effect increased with increasing cation loading and valency, andT* correlated with CA. Classical cross-linking can neither explain the higher heterogeneous matrix of Ca-treated than Al-treated samples nor the aging-induced convergence ofT* for different cations and concentrations. The latter is likely due to interaction between CaB and WaMB in SOM.ConclusionsAssociations of CaB and WaMB evolve slowly and form a supramolecular network in SOM. Those dynamic associations can fix molecular arrangements inducing water repellency and increase kinetic barriers for the release and uptake of water and nutrients from aged soil.