Mineral magnetic properties of Chinese paddy soils and its pedogenic implications
Mineral magnetic properties of Chinese paddy soils and its pedogenic implications
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中国水稻土的矿磁特性及其成土意义
DOI：
10.1016/j.catena.2012.01.002
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发表时间：
2012-06
期刊：
影响因子：
6.2
通讯作者：
J.Y.Yu
中科院分区：
文献类型：
--
作者：
S.G.Lu;L.Zhu;J.Y.Yu
为了更好地了解水稻土的磁性剖面特征和成土磁性矿物，测定了浙江省水稻土及其相应的旱地土壤的磁化率。磁性测定结果表明，同一母质上形成的水稻土的MS值远低于旱地土壤。原旱地土壤MS值越高，种植水稻后MS值下降越显著。潜育水稻土表现出非常低的MS值（<20×10− 8 m3 kg −1）和频率敏感性（<3%），以及MS对加热的更大增强。淹水培养实验表明，土壤MS的损失主要发生在水分饱和后的第15天至第75天。在180天的还原期内，第四纪红粘土和冲积存款上发育的土壤MS总损失分别为78%和80%。水稻土各粒级的MS值也远低于相同母质上形成的旱地土壤。水稻土粘粒中磁性颗粒的损失最大，说明粘粒中磁性颗粒易被溶解。热磁（κ-T）分析表明，水稻土MS随温度的升高表现出非常复杂的行为，这可以用氧化铁在弱晶相中占优势来解释。磁化率的热行为表明水铁矿在水稻土的所有剖面中都存在。水稻土的淀积层富含结晶纳米尺度的氧化铁相（主要是针铁矿，赤铁矿，磁赤铁矿/磁铁矿）。水稻土中的氧化还原循环可导致纳米氧化铁的形成，这为解释成壤磁性矿物的形成提供了新的途径。由于土壤水文条件的差异，水稻土磁性剖面表现出明显的分异。水稻土中MS谱的分布可分为3种类型。水稻土MS的分异可用于描述土壤剖面特征、识别诊断层和解释土壤水文状况。研究结果为水稻土剖面描述、类型识别、水文动态诊断提供了新的工具。研究结果也有助于理解土壤磁动力学过程中所造成的渍害。
Magnetic susceptibility (MS) of paddy soils (Hydragric Anthrosols) and their corresponding dryland soils formed on the same parent materials in Zhejiang Province of Eastern China were measured in order to understand better magnetic profile discrimination and pedogenic magnetic minerals in paddy soils. Magnetic measurements showed that the MS values of paddy soils were much lower than those of dryland soils formed on the same parent materials. The higher the MS value of the original dryland soil is, the more remarkable the decrease in the MS value is when the soil is put under rice cultivation. Gleyed paddy soils exhibited very low MS value (<20×10−8m3kg−1) and frequency-dependent susceptibility (<3%), as well as greater enhancement of MS on heating. Waterlogging incubation experiment indicated that the MS loss of soil mainly occurred in day 15 to day 75 after water saturation. During the reduction period of 180days, the overall MS losses of soils developed on Quaternary red clay and alluvial deposit were 78% and 80%, respectively. The MS values of various particle size fractions in paddy soils were also much lower than those of dryland soils formed on the same parent materials. The largest loss in MS value occurred in the clay fraction of paddy soil, which suggested that magnetic grains in clay fraction were readily dissolved. Thermomagnetic (κ–T) analysis indicated that paddy soils had very different and complex behavior of MS with increasing temperature, which can be explained by the predominance of ferric oxide in a poorly crystalline phase. Thermal behavior of magnetic susceptibility suggested that ferrihydrite was present in all profiles of paddy soils. The illuvial horizon of paddy soils was enriched with crystalline nano-scale iron oxide phase (mainly goethite, hematite, and maghemite/magnetite). The oxidation and reduction cycle in paddy soils could lead to the formation of nanocrystalline iron oxide, which provided a new pathway to explain the formation of pedogenic magnetic minerals. Paddy soils showed an obvious magnetic profile differentiation due to the difference in soil pedo-hydrological regimes. Three distribution patterns of MS profiles could be identified in paddy soils. The differentiation of MS in paddy soils can be used to describe soil profile characterization, identify diagnostic horizon, and interpret soil hydrological regimes. These findings provided new tool for profile description, type identification, hydrological regime diagnosis of paddy soils. Our results also help understand magnetic dynamic of soils caused by waterlogging process.
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影响因子：
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