Mineralogical study of arsenic-enriched aquifier sediments at Santiago del Estero, Northwest Argentina

Sracek, O. and Novak, M. and Sulovsky, P. and Martin, R. and Bundschuh, J. and Bhattacharya, P. (2009) Mineralogical study of arsenic-enriched aquifier sediments at Santiago del Estero, Northwest Argentina. In: Natural arsenic in groundwaters of Latin America. Arsenic in the Environment, 1. Taylor & Francis (CRC Press), London, United Kingdom, pp. 61-67. ISBN 9780415407717

Abstract

Ashallowaquifer in an alluvial fan at Santiago del Estero, northwestern Argentina, is enriched in arsenic (As). Sediments from sites with high As concentration were collected by hand auger and studied by X-ray diffraction and by electron microprobe. X-ray diffraction confirmed
the presence of quartz and albite. Concentration of total organic carbon (TOC) in soil is low, but concentration of total inorganic carbon (TIC) may be significant. The electron microprobe investigation found abundant glass particles with fluidal structure. The grains show significant weathering features such as voids and dissolution pits. Biotite grains present in sediments are
also weathered. Iron oxyhydroxides occur in isolated spots on the surface of silicate minerals, but not as continuous coatings. Heavy minerals were represented by altered ilmenite, monazite, zircon, and garnet with predominant almandine component. The primary source of As could
not be determined unequivocally, but volcanic glass and biotite are potential candidates. Ferric
oxyhydroxides, which are important adsorbents of As, seem to have formed by precipitation of iron released from minerals like titano-magnetite, and ilmenite. However, the amount of precipitated ferric oxides and hydroxides is low and, furthermore, their As adsorption capacity depends on
factors like pH and ionic strength of groundwater and on concentrations of species competing for adsorption sites.


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Item Type: Book Chapter (Commonwealth Reporting Category B)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to published version due to publisher copyright policy. Print copy not held in the USQ Library.
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 06 Nov 2014 01:25
Last Modified: 06 Nov 2014 01:25
Uncontrolled Keywords: arsenic; sediments; aquifiers; Santiago del Estero
Fields of Research : 05 Environmental Sciences > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment
04 Earth Sciences > 0406 Physical Geography and Environmental Geoscience > 040603 Hydrogeology
URI: http://eprints.usq.edu.au/id/eprint/26261

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