Microprobe techniques for speciation analysis and geochemical characterization of mine environments: the mercury district of Almadén in Spain.
Metallurgic calcines with very high mercury and methylmercury content from the Almadén mining district were analyzed by synchrotron-based microprobe techniques. Information about mercury speciation was obtained by micro-EXAFS (microscopic extended X-ray absorption fine structure) spectroscopy, whereas elemental associations were evaluated by micro-XRF (microscopic X-ray fluorescence analysis) mapping. Complementary characterization methodologies, including X-ray diffraction (XRD), inductively coupled plasma-optical spectroscopy (ICP-OES), as well as a sequential extraction scheme (SES), were used to predict the potential availability of mercury. Analysis of total metal content revealed extremely high concentrations of mercury and iron (between 7 and 35 and 65-70 g kg(-1), respectively) and high zinc concentrations (2.2-2.5 g kg(-1)), whereas other metals such as copper, nickel, and lead were found at low concentration levels (30-300 mg kg(-1)). Micro-EXAFS results indicate that cinnabar (HgS(red)) is one of the main species within the studied mercury-rich particles (5-89% of total mercury content), together with more soluble mercury compounds such as Hg3(SO4)02 (schuetteite) and HgO (5-55% of total mercury content). Additionally, element-specific micro-XRF maps of selected mercury-rich particles in the studied samples revealed an evident correlation among Hg-Pb-Ni (and S), indicating a possible geochemical linkage of these elements. Correlations were also found among Fe-Mn and Hg, which have been attributed to sorption of mercury onto oxyhydroxides of Fe and Mn. This finding was supported by results from a sequential extraction scheme, where a significant
Bernaus
Anna
A
Grup de Théniques de Separació en Química (GTS), Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
Gaona
Xavier
X
Esbrí
José Maria
JM
Higueras
Pablo
P
Falkenberg
Gerald
G
Valiente
Manuel
M
D004784:Environmental Monitoring; D007220:Industrial Waste / Q000032:analysis*; D008628:Mercury / Q000032:analysis*; D008669:Metallurgy; D019216:Metals, Heavy / Q000032:analysis; D008767:Methylmercury Compounds / Q000032:analysis*; D008906:Mining; D013030:Spain; D013057:Spectrum Analysis / Q000379:methods; D014961:X-Ray Diffraction
D007220:Industrial Waste; D019216:Metals, Heavy; D008767:Methylmercury Compounds; D008628:Mercury