The influence of gleyzation on the chemical composition of the lysimetric water and the physicochemical properties of the parent rocks: A model experiment

The influence of gleyzation and sulfate reduction on lysimetric waters collected from different heavy-textured soil-forming rocks (river alluvium, loess-like clays, and lacustrine-alluvial deposits) is considered. Under the stagnant-percolative water regime, the gleyzation caused the acidification of the waters (by 1.5-2.5 pH units); the intense removal of iron, calcium, and silica; a drastic decrease of the base saturation; and an increase in the hydrolytic (total) acidity. The content of mobile aluminum in the soils, as compared to the parent rock, increased by tens of times; under a stagnant water regime, the changes in the physicochemical soil properties were less significant or absent. The maximum removal of iron was found from the river alluvium followed by that from the loess-like clay and saline lacustrine alluvium. Unlike the other elements, the greater removal of silica was observed not at the beginning of the experiment (as in the case with iron and calcium) but at its end. A preliminary conclusion was suggested that the considerable increase of the silica concentration in the lysimetric water after the long-term effect of gleying under the stagnant-percolative water regime was related to the destruction of aluminosilicates.