Hostname: page-component-78c5997874-ndw9j Total loading time: 0 Render date: 2024-11-19T11:42:16.376Z Has data issue: false hasContentIssue false
  • English
  • Français

Mineralogical controls on arsenic mobility in the Baccu Locci stream catchment (Sardinia, Italy) affected by past mining

Published online by Cambridge University Press:  05 July 2018

F. Frau  and
C. Ardau
F. Frau*
Affiliation:
Dipartimento di Scienze della Terra, Università di Cagliari, Via Trentino, 51, I-09127, Cagliari, Italy
C. Ardau
Affiliation:
Dipartimento di Scienze della Terra, Università di Cagliari, Via Trentino, 51, I-09127, Cagliari, Italy
*
*E-mail: frauf@unica.it
Get access Rights & Permissions [Opens in a new window]

Abstract

Mineralogical-chemical techniques (XRD, SEM/EDX, WDXRF) and a sequential selective extraction procedure were applied to mine-waste materials and stream sediments from the Baccu Locci stream catchment (Sardinia, Italy) affected by serious As contamination as a consequence of past mining. Results indicate that solid-state speciation of As is mainly dominated by the presence of Fe(III) hydroxides (arsenical ferrihydrites with various Fe/As molar ratios) occurring as coatings of silicate grains, in which As is contained as sorbed or co-precipitated species. Scorodite (FeAsO4·2H2O) is common too, whereas arsenopyrite is generally subordinate but, owing to its relatively rapid oxidation, environmentally significant. Moreover, some unidentified arsenates of Ca-Fe or K-Fe were also detected. Arsenic contained in these phases is slowly, but continuously, released in relatively small amounts through three main mechanisms: (1) oxidation of residual arsenopyrite to scorodite; (2) decomposition of scorodite into a hydroxide or oxide of Fe(III); (3) desorption/release from Fe(III) hydroxides. Decomposition of the unidentified arsenates is also probable, e.g. Ca-Fe arsenate → calcite + Fe(III) hydroxide + As release. The flotation tailings are widely scattered and distributed in the middle–lower Baccu Locci stream catchment, and represent the most dangerous As-generating contamination source in the study area.

Keywords

arsenicsolid-state speciationsequential extractionsmine-waste materialsenvironmental mineralogyBaccu Locci mineSardiniaItaly
Type
Research Article
Information
Mineralogical Magazine , Volume 68 , Issue 1 , February 2004 , pp. 15 - 30
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2004

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ardau, C. (2001) Mineralogia e geochimica dell’arsenico nell’area mineraria dismessa di Baccu Locci. PhD thesis (in Italian), Univ. Cagliari, Italy.Google Scholar
Bakos, F., Carcangiu, G., Fadda, S., Mazzella, A. and Valera, R. (1990) The gold mineralization of Baccu Locci (Sardinia, Italy): origin, evolution and concentration processes. Terra Nova, 2, 234–239.CrossRefGoogle Scholar
Bowell, R.J. (1994) Sorption of arsenic by iron oxides and oxyhydroxides in soils. Applied Geochemistry, 9, 279–286.CrossRefGoogle Scholar
Campostrini, I. and Gramaccioli, C.M. (2001) Seleniumrich secondary minerals from the Baccu Locci mine (Sardinia, Italy). Neues Jahrbuch für Mineralogie, Abhandlungen, 177, 37–59.CrossRefGoogle Scholar
Dove, P.M. and Rimstidt, J.D. (1985) The solubility and stability of scorodite, FeAsO4·2H2O. American Mineralogist, 70, 838–844.Google Scholar
Dzombak, D.A. and Morel, F.M.M. (1990) Surface Complexation Modeling: Hydrous Ferric Oxide. John Wiley & Sons, New York.Google Scholar
Förstner, U. (1993) Metal speciation–General concepts and appli cat ions. International Journal of Environmental Analytical Chemistry, 51, 5–23.CrossRefGoogle Scholar
Frau, F. and Ardau, C. (2003) Geochemical controls on arsenic distribution in the Baccu Locci stream catchment (Sardinia, Italy) affected by past mining. Applied Geochemistry, 18, 1373–1386.CrossRefGoogle Scholar
Fuller, C.C., Davies, J.A. and Waychunas, G.A. (1993) Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation. Geochimica et Cosmochimica Acta, 57, 2271–2282.CrossRefGoogle Scholar
Krause, E. and Ettel, V.A. (1988) Solubility and stability of scorodite, FeAsO4·2H2O: New data and further discussion. American Mineralogist, 73, 850–854.Google Scholar
Londesborough, S., Schlegel, D., Fankhänel, U., Mattusch, J. and Wennrich, R. (1997) Einsatz eines sequ entiel len Extra kt ionsve rfahr ens für die Best immungvon Arsen spezies in Tailingsmaterialien. CANAS ‘97 Colloquium Analytische Atomspektroskopie, 559–563.Google Scholar
Nesbitt, H.W., Muir, I.J. and Pratt, A.R. (1995) Oxidation of arsenopyrite by air and air-saturated, distilled water, and implications for mechanism of oxidation. Geochimica et Cosmochimica Acta, 59, 1773–1786.CrossRefGoogle Scholar
Nordstrom, D.K. and Parks, G.A. (1987) Solubility and stability of scorodite, FeAsO4·2H2O: Discussion. American Mineralogist, 72, 849–851.Google Scholar
Pierce, M.L. and Moore, C.B. (1980) Adsorption of arsenite and arsenate on amorphous iron hydroxide from dilute aqueous solution. Environmental Science and Technology, 14, 214–216.CrossRefGoogle Scholar
Pierce, M.L. and Moore, C.B. (1982) Adsorption of arsenite and arsenate on amorphous iron hydroxide. Water Research, 16, 1247–1253.CrossRefGoogle Scholar
Rimstidt, J.D. and Dove, P.M. (1987) Solubility and stabili ty of scorodit e, FeAsO4·2H2O: Reply. American Mineralogist, 72, 852–855.Google Scholar
Rimstidt, J.D., Chermak, J.A. and Gagen, P.M. (1994) Rates of reaction of galena, sphalerite, chalcopyrite and arsenopyrite with Fe(III) in acidic solutions. Pp. 3–13 in: Environmental Geochemistry of Sul. de Oxidation (Alpers, N.C. and Blowes, D.W., editors). ACS Symposium Series 550.Google Scholar
Riveros, P.A., Dutrizac, J.E. and Spencer, P. (2001) Arsenic disposal practices in the metallurgical industry. Canadian Metallurgical Quarterly, 40, 395–420.CrossRefGoogle Scholar
Robins, R.G. (1987) Solubility and stability of scorodite, FeAsO4·2H2O: Discussion. American Mineralogist, 72, 842–844.Google Scholar
Sørensen, M.A., Stackpoole, M.M., Frenkel, A.I., Bordia, R.K., Korshin, G.V. and Christensen, T.H. (2000) Aging of iron (hydr)oxides by heat treatment and effects on heavy metal binding. Environmental Science and Technology, 34, 3991–4000.CrossRefGoogle Scholar
Swash, P.M. and Monhemius, A.J. (1995) Synthesis, characterization and solubility testing of solids in the Ca-Fe-AsO4 system. Pp. 17–28 in: Mining and the Environment (Ilynes, T.P. and Blanchette, M.C., editors). Sudbury ‘95 CANMET, Ottawa, Canada.Google Scholar
Zucchetti, S.C. (1958) The lead-arsenic-sul. de ore deposit of Bacu Locci (Sardinia-Italy). Economic Geology, 53, 867–876.CrossRefGoogle Scholar