Thallium contamination of desert soil in Namibia: Chemical, mineralogical and isotopic insights. (August 2018)

• Record Type: Journal Article
• Authors: Grösslová, Zuzana; Vaněk, Aleš; Oborná, Vendula; Mihaljevič, Martin; Ettler, Vojtěch; Trubač, Jakub; Drahota, Petr; Penížek, Vít; Pavlů, Lenka; Sracek, Ondra; Kříbek, Bohdan; Voegelin, Andreas; Göttlicher, Jörg; Drábek, Ondřej; Tejnecký, Václav; Houška, Jakub; Mapani, Benjamin; Zádorová, Tereza
• Is Part Of: Environmental pollution. Volume 239(2018)
• Page Start: 272
• Page End: 280
• Publication Date: 2018-08
• Subjects: Soil -- Tl isotopes -- Mining waste -- Contamination; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.04.006
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: We studied arid desert soils from Namibia (Rosh Pinah) that were contaminated with up to 7 mg kg −1 of thallium (Tl) via dust emitted from a local flotation tailing dam. Chemical extractions of waste and soil materials indicated that most of the Tl is strongly bound, in accordance with X-ray diffraction and X-ray absorption spectroscopy data that point to the predominant association of Tl with metal sulfides and phyllosilicates. The isotope fractionation factor ε 205 Tl of the soil samples (from −0.4 to +3.8) shows a positive linear relationship (R 2 = 0.62) with 1/Tl, indicative for the mixing of two major Tl pools, presumably anthropogenic Tl and geogenic Tl. The ε 205 Tl value for the topmost soil samples (∼+3) closely matches the ε 205 Tl value for post-flotation waste particles with a diameter of <0.05 mm, whereas the bulk flotation waste exhibits a significantly larger ε 205 Tl value (∼+6). These variations are in accordance with predominant atmospheric transfer of Tl from the tailings to the adjacent soils via fine (dust) particles. The identified minimal Tl alteration in soils indicates that only a small part of the Tl could be potentially released and passively enter the vegetation, local population and/or food chain in the long term. From this viewpoint, Tl does not represent such an important environmental concern as other (abundant) contaminants at the locality. Furthermore, there could be a relevance for other alkaline desert soils, including those where Tl pollution plays a major role. Graphical abstract: Image 1 Highlights: Thallium contamination may be traced using Tl isotopes. Thallium is very stable in mining wastes/soils compared to other metals. Thallium migrates in the form of (micro)particles. A large isotope variation among different-sized waste materials. First study dealing with Tl and Tl isotopes in a desert area. Abstract : Thallium isotopes may be used for tracing Tl pollution and particulate Tl migration in desert areas.