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土壤磁性变化机制的研究中,越来越多的证据指示成壤作用的影响,而土壤理化性质是其分类的主要因素,却很少有关于土壤理化性质与磁化率关系的研究报道。通过对碳酸盐岩上覆红色石灰土的酸碱处理实验,探究土壤pH值与其磁化率的影响。研究结果表明:酸碱处理前,红色石灰土的磁化率集中在3 000～4 500×10-8m3/kg,pH值在7～8,为碱性土壤;经HCl溶液处理后,pH值下降到1～4,磁化率下降到250～4 000×10-8m3/kg,pH值与磁化率呈现正相关关系;经NaOH溶液处理后,pH值上升到8～13,磁化率反而下降到2 500～4 000×10-8m3/kg,pH值与磁化率呈现负相关关系。上述现象的产生,与酸和强碱所分别带来的还原和氧化环境有关,改变了弱磁性矿物和强磁性矿物之间的转化方向,抑制了趋磁细菌作用,最终引起土壤磁化率的变化。
In the study of the mechanism of soil magnetism change, more and more evidences indicate the influence of pedogenesis. However, the soil physical and chemical properties are the main factors of its classification. However, there are few reports on the relationship between soil physical and chemical properties and susceptibility. Through the experiment of acid-alkali treatment on carbonate overlying red limestone soil, the influence of soil pH value and its magnetic susceptibility was investigated. The results showed that before acid-alkali treatment, the susceptibility of red limestone was concentrated in the range of 3 000-4 500 × 10-8 m3 / kg and the pH value was in the range of 7-8, which was alkaline soil. After treated with HCl solution, the pH decreased To 1 ~ 4, the magnetic susceptibility decreased to 250 ~ 4 000 × 10-8m3 / kg, pH and magnetic susceptibility showed a positive correlation; treated with NaOH solution, the pH value rose to 8 ~ 13, but the magnetic susceptibility decreased to 2 500 ~ 4 000 × 10-8m3 / kg, pH and magnetic susceptibility showed a negative correlation. The above phenomenon is related to the reduction and oxidation environment respectively brought by acid and alkali, changing the direction of transformation between weak magnetic minerals and ferromagnetic minerals, inhibiting the action of magnetotactic bacteria and eventually causing the change of soil magnetic susceptibility .