Stability of Arsenic Species in Soils Contaminated Naturally and in an Anthropogenic Manner
2008
Doušová, Barbora | Martaus, Alexandr | Filippi, Michal | Koloušek, David
Stability and transport of As species in soils were investigated in three contaminated Central European regions in the Czech Republic; one of them represents naturally contaminated area, the others are results of a former mining activity. Total As content varied from 60 to <18,000 ppm depending on locality and sampling layer. Sequential extraction procedure (SEP) enabled to distinguish five main fractions of As in soils based on different chemical and binding properties. Non-specifically and weakly sorbed As, as well as As remained in solid rests of samples did not exceed 10% of total As; specifically bounded As varied from 5 to 15%. The substantial portion of As was bound to hydrated Fe oxides (HFO) in amorphous and poorly-crystalline forms (10-30% of the total As) and/or to a well-crystallized forms of the same phases (50-80%). As sorption on HFO surface, particularly on well-crystallized phases represented the most significant and stable As bond in soils. Model leaching experiments illustrated the increased mobility of As species at pH [almost equal to] 7.0 in the soil-groundwater-surface water systems.
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