Testing competing hypotheses for soil magnetic susceptibility using a new chemical kinetic model
Testing competing hypotheses for soil magnetic susceptibility using a new chemical kinetic model
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DOI：
10.1130/g31514.1
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发表时间：
2010-12-01
期刊：
影响因子：
5.8
通讯作者：
Hannam, Jacqueline A.
中科院分区：
文献类型：
--
作者：
Boyle, John F.;Dearing, John A.;Hannam, Jacqueline A.
利用实验测定的速率常数建立了次生亚铁磁性矿物(SFMS)在土壤中形成和积累的化学动力学模型，并与野外数据进行了验证。主要目标是对温带条件下相互竞争的因果机制和有争议的环境控制的重要性进行批判性评估。关于土壤磁化率数据的当前应用，有四个发现是重要的。首先，水合氧化铁向磁铁矿的转化应主导SFM的形成，主要受母质硅酸亚铁浓度和气候的控制。其次，非生物反应应该占SFM产生的大部分；异化铁还原细菌产生的高Fe2+浓度最显著的影响是增加了径流中土壤中铁的输出。第三，该模型预测了赤铁矿和磁铁矿浓度之间的相关性，削弱了水合氧化铁直接转化为磁铁矿的场强支持。第四，磁化率增强应随风化时间的延长而增强。
A chemical kinetic model is presented for the formation and accumulation of secondary ferrimagnetic minerals (SFMs) in soil constructed using experimentally determined rate constants and validated against field data. The primary objective is to critically assess the significance of competing causal mechanisms and disputed environmental controls under temperate conditions. Four findings are important in relation to current application of soil magnetic susceptibility data. First, transformation of hydrous ferric oxide to magnetite should dominate SFM formation, controlled primarily by parent material ferrous silicate concentration and climate. Second, abiotic reactions should account for most of the SFM production; the most significant impact of high Fe2+ concentrations created by dissimilatory iron-reducing bacteria is enhanced export of iron from the soil in runoff. Third, the model predicts a correlation between hematite and magnetite concentrations, weakening field support for direct transformation of hydrous ferric oxide to maghemite. Fourth, magnetic susceptibility enhancement should increase strongly with weathering duration.