Abstract

Strongly acid soils (pH_KCl < 3.3) are widespread in the northeast of European Russia and are characterized by the low precision of potentiometric measurements of the components of exchangeable acidity. The goal of our study was to identify the causes that reduce the precision of measuring the exchangeable acidity of these soils using single- and two-component model systems of aluminum and iron(III) ions in concentrations similar to those in extracts from the strongly acid soils. Using model solutions, it was shown that the high acidity of salt extracts from soils is caused by the presence of iron(III) ions. The precision of measurements of metal ions was determined by the mode of stirring of the analyzed solution (continuous or discrete), as well as by the duration of interaction of the titrant with it. This was due to the presence of disperse systems in the initial model solutions. Particle parameters (hydrodynamic diameter D 70–90 nm, ζ-potential 19–30 mV) were determined by the dynamic light scattering and laser Doppler electrophoresis. The presence of other components—organic compounds and fine particles of silicates and iron hydroxides capable of passing through the blue ribbon filter pores in the salt extracts from soils—further reduces the precision of measuring the total Al³⁺ and Fe³⁺ content (exchangeable acidity) by the potentiometric method and casts doubt on the possibility of its application. When working with strongly acid soil samples, the use of atomic emission method is recommended.

中文翻译：

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含可交换铁（III）模型系统在研究强酸性土壤（pH KCl <3.3）的酸度特征中的应用

摘要

强酸性土壤（pH _KCl<3.3）在欧洲俄罗斯的东北部广泛存在，其特征在于可交换酸度的电位计测量精度低。我们研究的目的是查明使用铝和铁（III）离子浓度与强酸提取物中浓度相似的单组分和二组分模型系统，降低测量这些土壤的可交换酸度的精度的原因。土壤。使用模型溶液表明，土壤中盐分提取物的高酸度是由于铁（III）离子的存在引起的。金属离子的测量精度取决于所分析溶液的搅拌方式（连续或离散）以及滴定剂与其相互作用的持续时间。这是由于初始模型解决方案中存在分散系统。粒子参数（流体动力学直径D 70–90 nm，ζ电位19–30 mV）由动态光散射和激光多普勒电泳确定。其他成分的存在（能够穿过土壤盐分提取物中的蓝带过滤孔的有机化合物以及硅酸盐和氢氧化铁的细颗粒）进一步降低了总铝的测量精度通过电位法测定³⁺和Fe ^3+的含量（可交换酸度），并怀疑其应用的可能性。当处理强酸性土壤样品时，建议使用原子发射法。