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土壤中的氧化铁由于它本身所持有的特性(如专性吸附作用、胶结作用、活性较大,易随环境变化而改变其表面性质等)以及它对层状粘土矿物的深刻影响,从而使土壤中氧化铁研究的理论和实践意义,超越土壤化学、土壤发生学和土壤植物营养化学的范围,对土壤污染、地球化学等领域同样有密切关系。各种形态氧化铁的鉴定,除应用某些物理方法外,还需化学方法以辅助。连二亚硫酸钠—柠檬酸钠—重碳酸钠还原法和Tamm溶液(草酸铵缓冲液)提取法,迄今仍广泛地用于土壤或粘粒中游离氧化铁和无定形铁的测定。前一方法的依据较为充足,也较成熟。后者则带有一定程度的经验性,受提取条件的影响较大。本文拟对草酸铵溶液提取法作一评价,并根据试验结果对该法的提取条件进行讨论,最后将介绍无定形铁的测定技术,简要介绍活性铝和锰的测定。
Iron oxide in the soil due to its own characteristics (such as the role of special adsorption, cementation, activity, easy to change with the environmental changes in its surface properties, etc.) and its profound impact on the layered clay minerals, and thus The theoretical and practical significance of the research on iron oxide in soil goes beyond the fields of soil chemistry, soil genesis and soil plant nutrition chemistry and is also closely related to the fields of soil pollution and geochemistry. Identification of various forms of iron oxide, in addition to the application of some physical methods, the need for chemical methods to assist. Sodium dithionite - sodium citrate - sodium bicarbonate reduction method and Tamm solution (ammonium oxalate buffer) extraction method, so far is still widely used in soil or clay particle determination of free iron oxide and amorphous iron. The basis of the former method is more adequate and more mature. The latter with a certain degree of experience, affected by the extraction conditions. This article intends to evaluate the extraction method of ammonium oxalate solution. According to the test results, the extraction conditions of the method are discussed. Finally, the determination of amorphous iron is introduced. The determination of active aluminum and manganese is briefly introduced.