Methodological aspects in the analysis of the content of mobile compounds of heavy metals in hydromorphic soils
2020
Vodyanitskii, Yuriy | Minkina, Tatiana | Zamulina, Inna
The content of mobile compounds of Zn, Pb and Cu in the hydromorphic soil samples with natural humidity from southern European Russia turned out to be much higher than in samples stored in laboratory for 1 month and, particularly, 3 years. At the same time, the extractability of heavy metals is characterized by irregular kinetics: their solubility decreases rapidly during the first month when the dry soil sample loses the initial humidity, but slowly during its further storage for 3 years. Solubility of metals in natural humid soils is highly variable. Influence of the studied reagents (CH₃COONH₄, EDTA and oxalate) shows the following general trend: Zn > Pb ≫ Cu. Solubility difference of metals is smoothed over in the course of soil drying. In terms of the dissolution efficiency of mobile metal compounds in the hydromorphic ferruginated soils, the extractants are arranged in the following order: oxalate > EDTA > CH₃COONH₄. Since the oxalate actively dissolves Fe(II)-compounds in soils, the solubility of metal is governed by the its siderophility. Zn is most intensely dissolved by oxalate, while Pb and Cu in soils demonstrate organophilic properties. However, Pb can also be sorbed on iron hydroxide particles.
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