Mobilization of Antimony and Arsenic in Soil and Sediment Samples – Evaluation of Different Leaching Procedures

Abstract

This study aims to evaluate the performance of different leaching schemes with respect to the mobilization of antimony and arsenic from polluted samples collected at different sites in Mansfeld District, Germany. Besides the elution by water the leaching by artificial acidic rain and by two different schemes of sequential extraction were employed for estimation of the mobilization of antimony and arsenic. The samples were characterized by X-ray fluorescence analysis for their total concentration of metalloids, metals and main constituents. It was found that both antimony and arsenic show little mobilization with de-ionized water as well as artificial acidic rain in single step batch procedures (≤ 0.13% of the total content). Although the percentage leached is very low, the concentrations in the resulting solutions are of ecotoxicological relevance. BCR procedure indicate a very strong binding of Sb and of As in the samples. Less than 20% of the total content can be leached in sum in all leaching steps, of it most under strongly oxidizing conditions. This scheme seems not suitable for a detailed investigation of possible mobilization processes under environmental conditions for the metalloids under investigation. The four-step extraction procedure by Wenzel et al. gives a more detailed pattern of the binding of antimony and arsenic. This procedure was found to be a suitable scheme for evaluating the possible mobilization processes from the samples contaminated by ore processing waste, especially by change through other ions or under reducing conditions.

Relationship between Metals Leached and Soil Type from Potential Acid Sulphate Soils under Acidic and Neutral Conditions in Western Australia

“…The preservation factor is also believed to have influenced the correlations seen between total metal concentrations (mg kg −1 ) and leached metal concentrations (mg L −1 ) in the batch trial. The correlations were unexpected as numerous studies have shown that total metal concentration alone is unreliable for predicting mobilisation of metals (Ge et al 2000;Dijkstra et al 2004;Müller et al 2007), however, Åström (1998) observed a positive correlation between total Mn concentrations in fine grained actual acid sulphate soil and leached Mn. In this study of PASS, the only correlation for Mn (moderate correlation) was shown for the peat samples.…”

“…This study has generated new information on the behaviour of common soil types containing potential acid sulphate materials in south-western Australia Table 4 Median concentrations (µg L −1 ) of seven metals in leachates from four soil types (peat, silty sand, SS; iron-rich sand, FeRS; and grey sand, GS) (Suh et al 2003;He et al 2006;Müller et al 2007), whereas fewer studies compare leachates from multiple soil types under the same conditions. Pyrite was not detectable by XRD analysis in most samples but was previously assumed present as chromium-reducible sulphur concentrations averaged 0.5% w/w for the batch samples and 0.28% w/w for the column samples.…”

“…Leaching test comparisons show that different leaching methods generate different information (Hage and Mulder 2003;Müller et al 2007). Leaching procedures must therefore be chosen specifically to generate the information required.…”

Distribution, speciation and availability of antimony (Sb) in soils and terrestrial plants from an active Sb mining area

“…Sequential chemical extraction of soil (Table 2) was carried out using a modified method developed for As based on extractants commonly used for the oxyanions selenium (Se) and phosphorous (P) (Wenzel et al, 2001). Earlier this procedure was used by Muller et al (2007) for Sb and As and found to be suitable for evaluating the possible mobilization processes from samples contaminated by ore processing waste. The ammonium-oxalate buffer extraction in the original method to remove amorphous Fe, Al and Mn-oxides was excluded in the modified method because Sb also desorbs from crystalline Fe oxides in the presence of oxalate (Leuz, 2006).…”

“…2) show that the SO 4 2À extractable Sb fraction in the soil, which represents the non-specifically bound and easily leachable fraction in the soil (Wenzel et al, 2001;Muller et al, 2007), varied between 5 (S10) and 493 (S5) Extraction with oxalate and ascorbic acid, which represents the fraction associated with amorphous and crystalline Fe, Al and Mn oxides, dissolved a relatively large fraction of total Sb (22e66%) ( Table 5). Antimony concentration in the residue of the soil samples (acid digestion) varied between 24 and 77% of total Sb.…”