title: Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain).
abstract: Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system.
authors.affiliation: National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006 Madrid, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Gomez-Gonzalez
authors.affiliation: National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006 Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Garcia-Guinea
authors.affiliation: Group of Analytical Spectroscopy and Sensors Group, Institute of Environmental Sciences, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Laborda
authors.affiliation: National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006 Madrid, Spain. Electronic address: fernando.garrido@mncn.csic.es.
authors.forename: F
authors.initials: F
authors.lastname: Garrido
mesh_terms: D004784:Environmental Monitoring; D008906:Mining; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D013030:Spain; D013793:Thallium / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D013793:Thallium
keywords: Ag–Cu ores; Cathodoluminescence; Soil contamination; Thallium