Arsenic mobility from anthropogenic impoundment sediments – Consequences of contamination to biota, water and sediments, Poša, Eastern Slovakia

An impoundment located near the village of Poša, Slovakia, is a significant source of contamination with As originating from the deposited coal fly-ashe. Waters penetrating the impoundment are enriched in As and other potentially toxic elements. As a consequence of the contamination, the Kyjov Brook and the Ondava River have been extensively polluted. The mobility and solid-state partitioning of As in the impoundment material and stream sediments were investigated using column leaching and batch extraction tests, and a five-step sequential extraction procedure. Moreover, to investigate the bioavailability of As, two native plant species (Typha latifolia, or cattail, and Phragmites australis, or common reed) growing at the site were collected and analyzed. The As concentrations in representative sediment and water samples ranged from 36.3 to 3210 mg/kg and from 4.05 to 613 μg/L, respectively, both being many times above the background levels. Although a part of As was present in a readily soluble form (6.6%), the majority of As was mainly associated with Fe and Mn oxides (37%) and residual phases (51%). Combined results of the column leaching, batch extraction, and sequential extraction tests, as well as mineralogical analysis, indicated that As mobilisation potential from the sediments is likely controlled by Fe, Al and Mn oxides, and by pH. There was no influence of various anions (image, image) on As mobility when present in aqueous solution at concentrations analogous to those in the water of the Kyjov Brook. Plants growing in the impoundment had As concentrations 10–100 times greater than did the same plants growing in a relatively non-polluted area.