Magnetic imprints of pedogenesis in Planosols and Stagnic Alisol from Bulgaria
Magnetic imprints of pedogenesis in Planosols and Stagnic Alisol from Bulgaria
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DOI：
10.1016/j.geoderma.2010.10.018
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发表时间：
2011-01
期刊：
影响因子：
6.1
通讯作者：
N. Jordanova;D. Jordanova;P. Petrov
中科院分区：
文献类型：
--
作者：
N. Jordanova;D. Jordanova;P. Petrov
土壤中铁的各种形式是过去和/或正在进行的环境过程的重要指标。利用磁性方法可以获得与特定土壤类型相关的高分辨率氧化铁矿物学。白浆土是一种特殊的土壤类型，其特征是表面积水，导致随着深度的增加而产生巨大的质地差异。本研究提出了磁性调查的三个白浆土和Stagnic泽泻土从保加利亚结合传统的化学提取方法（草酸盐，柠檬酸盐，连二亚硫酸盐）和土壤性质表征（pH值，粒度级，和有机碳含量）。对高分辨率取样深度剖面进行了广泛的磁性分析，以确定氧化铁矿物、其稳定性和有效磁性粒度随深度的变化。铁氧化物溶解强烈的区域（最表层土壤）的强磁性矿物含量被磁性耗尽，但通过比率χ77/χ 293检测到的顺磁性含量相应增强。然而，漂白残积层层中含有稳定的结晶磁铁矿/磁赤铁矿部分，尽管含量很低。我们将此归因于从最高腐殖质层的磁铁矿/磁赤铁矿的lesivage和易位的过程。氧化铁矿物学的主要结果表明，薄腐殖层富含成土磁赤铁矿。磁化率的热行为表明，水铁矿存在于腐殖质和残积层的所有剖面。在白浆土的淀积层中，常见的矿物是纤铁矿，而在Alisol中，常见的矿物是Al取代的赤铁矿。浮土和水耕泽泻土含有结晶不良和结晶良好的氧化铁。降雨量的增加和风化作用的增强导致了成壤相中结晶度较好的成壤相的比例增加。
Iron in its diverse forms in soils is an important indicator of a number of past and/or ongoing environmental processes. Iron oxide mineralogy pertinent to a particular soil type could be obtained with high resolution using magnetic methods. Planosols are a particular soil type characterized by surface water-logging leading to development of great textural differentiation with depth. This study presents magnetic investigation on three Planosols and a Stagnic Alisol from Bulgaria combined with conventional chemical extraction methods (oxalate, citrate–dithionite) and soil property characterization (pH, grain size fractions, and organic carbon content). Extensive magnetic analyses on high-resolution sampled depth profiles have been done for determination of iron (oxyhydr)oxide minerals, their stability and variations of effective magnetic grain size with depth. Zones of intensive iron oxides dissolution – the topmost soil horizons – are magnetically depleted in the content of strongly magnetic minerals, but the paramagnetic content detected through the ratio χ77/χ293is enhanced accordingly. Bleached eluvial horizons, however, contain stable crystalline magnetite/maghemite fraction, albeit in a trace amounts. We ascribe this to the processes of lessivage and translocation of magnetite/maghemite from the topmost humus horizon. The main results on iron oxide mineralogy suggest that thin humus horizons are enriched with pedogenic maghemite. Thermal behavior of magnetic susceptibility suggests that ferrihydrite is present in humus and eluvial horizons of all profiles. In illuvial horizons of Planosols the common mineral is lepidocrocite, while in Alisol — Al-substituted hematite. Planosols and Stagnic Alisol contain both poorly crystalline and well crystalline iron oxides. Increasing precipitation and weathering leads to higher proportion of well crystalline pedogenic phases in the Alisol profile.