title: Comparison of extractants used for the assessment of mercury availability in a soil from the Almadén mining district (Spain).
abstract: Single extraction methods have been extensively used to assess the availability of metals in polluted soils. This work focused on checking the feasibility of several chemicals, i.e. CaCl2, EDTA, diethylenetriaminepentaacetic acid (DTPA) and a low-molecular-weight organic acid mixture (rhizosphere-based method), to be used as extractants for mercury (Hg) in a soil from the Almadén mining district (Spain). Moreover, the effect of several experimental parameters, i.e. extraction time (0.5, 1, 2, 5, 16 and 24 h), concentration of extractant (0.01, 0.05, 0.1 and 1 M) and soil/extractant ratio (1:2, 1:5 and 1:10), on the amount of Hg extracted was investigated. The Hg extraction ability followed the descending order EDTA > rhizosphere-based method > DTPA ≈ CaCl2. This ranking was attributed to the higher complexation power of EDTA and organic acids. It was also found that extraction times between 2 and 5 h are required to avoid underestimation of mobile Hg and re-adsorption of the Hg previously extracted. Although some exceptions were found, Hg extraction efficiency was generally enhanced with higher extractant concentrations. Finally, the amount of Hg extracted by the four extractants increased with decreasing soil/extractant ratios.
authors.affiliation: Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo José Cela, s/n, 13071, Ciudad Real, Spain. Luis.Rromero@uclm.es.
authors.forename: Luis
authors.identifier: http://orcid.org/0000-0002-6368-6308
authors.initials: L
authors.lastname: Rodríguez
authors.affiliation: Department of Physical Chemistry, Faculty of Environmental Sciences and Biochemistry, University of Castilla-La Mancha, Avenida Carlos III, s/n, 45071, Toledo, Spain.
authors.forename: Jacinto
authors.initials: J
authors.lastname: Alonso-Azcárate
authors.affiliation: Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo José Cela, s/n, 13071, Ciudad Real, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Gómez
authors.affiliation: Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo José Cela, s/n, 13071, Ciudad Real, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Rodríguez-Castellanos
mesh_terms: D008628:Mercury; D008906:Mining; D012987:Soil; D012989:Soil Pollutants; D013030:Spain
chemical_list: D012987:Soil; D012989:Soil Pollutants; D008628:Mercury
keywords: Calcium chloride; DTPA; EDTA; Mercury; Metal availability; Rhizosphere-based method; Single extraction