Control of climate on soil charge characteristics through organic matter and clay mineral distributions in volcanic soils of Mt. Kilimanjaro, Tanzania
Control of climate on soil charge characteristics through organic matter and clay mineral distributions in volcanic soils of Mt. Kilimanjaro, Tanzania
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DOI：
10.1080/00380768.2021.1883998
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发表时间：
2021-02-27
影响因子：
2
通讯作者：
Funakawa, Shinya
中科院分区：
文献类型：
--
作者：
Lyu, Han;Watanabe, Tetsuhiro;Funakawa, Shinya
土壤阳离子交换量（CEC）是反映土壤肥力的重要指标，影响土壤中元素的循环。气候可能通过控制土壤次生矿物和有机质的分布来影响土壤CEC。本研究的目的是澄清气候对土壤的电荷特性的影响，在山。不同气候条件下的基利曼哈罗。对采自天山南北坡的15个土壤剖面的土壤进行了分析。基利曼哈罗沿着海拔梯度（海拔910-2800米）被收集起来。土壤的物理化学和矿物学性质，包括恒定和可变的电荷密度，进行了测定。研究地点的气候数据来自WorldClim数据库。结果表明，在东南坡隆起区的湿润站点，可变电荷对CEC的贡献较大。在潮湿的网站，高含量的有机质，这被认为是稳定的有机-无机复合物的纳米晶体矿物，扩大了土壤CEC，在凉爽的高海拔地区更为明显。而在西北坡和东南坡低海拔的干旱样地，恒定电荷和可变电荷对CEC的贡献相当。有机-矿物复合体的可变电荷较小，这是由于纳米晶体矿物在干燥条件下逐渐结晶，形成的结晶粘土矿物将有助于保持恒定的电荷密度。我们的研究表明，除了温度的重要性，水分的因素，影响有机质和结晶粘土矿物的分布，这反过来又控制土壤电荷特性。因此，在研究相对干燥地区的弱风化火山岩土时，除了考虑可变电荷外，还应考虑结晶粘土矿物的恒定电荷。
The soil cation exchange capacity (CEC), which is contributed by constant and variable charges, is a vital indicator of soil fertility and affects elemental cycling. Climate is expected to affect soil CEC by controlling soil secondary minerals and organic matter distributions. The objective of this study was to clarify the effects of climate on the charge characteristics of the soil in Mt. Kilimanjaro under diverse climatic conditions. The soils of 15 soil profiles from southeast and northwest slopes of Mt. Kilimanjaro along the elevation gradient (910-2800 m asl.) were collected. The soil physicochemical and mineralogical properties, including constant and variable charge densities, were determined. Climate data for the study site was obtained from the WorldClim database. The results showed that the contribution of the variable charge to CEC was high at the humid sites of the elevated area of the southeast slope. At the humid sites, the high content of organic matter, which was considered to be stabilized as organo-mineral complexes by nanocrystalline minerals, enlarged the soil CEC, being more evident at cool high elevation sites. On the other hand, at the dry sites on the northwest slope and low elevations of the southeast slope, the constant charge and variable charge contributed equally to the CEC. The variable charge from organo-mineral complexes was smaller due to the progressive crystallization of nanocrystalline minerals under the dry condition, and the formed crystalline clay minerals would contribute to constant charge density. Our study indicates the importance of moisture in addition to temperature as factors that influence the distribution of organic matter and crystalline clay minerals, which in turn control the soil charge characteristics. Thus, the constant charge from crystalline clay minerals should be considered in addition to the variable charge when studying the weakly weathered volcanic soils in the relatively dry regions.