Mobilisation of arsenic from bauxite residue (red mud) affected soils: Effect of pH and redox conditions

Cindy L. Lockwood, Robert J G Mortimer, Douglas I. Stewart, William M. Mayes, Caroline L. Peacock, David A. Polya, Paul R. Lythgoe, Alizée P. Lehoux, K. Gruiz, Ian T. Burke

Research output: Contribution to journalArticle

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Abstract

The tailings dam breach at the Ajka alumina plant, western Hungary in 2010 introduced ~1millionm3 of red mud suspension into the surrounding area. Red mud (fine fraction bauxite residue) has a characteristically alkaline pH and contains several potentially toxic elements, including arsenic. Aerobic and anaerobic batch experiments were prepared using soils from near Ajka in order to investigate the effects of red mud addition on soil biogeochemistry and arsenic mobility in soil-water experiments representative of land affected by the red mud spill. XAS analysis showed that As was present in the red mud as As(V) in the form of arsenate. The remobilisation of red mud associated arsenate was highly pH dependent and the addition of phosphate to red mud suspensions greatly enhanced As release to solution. In aerobic batch experiments, where red mud was mixed with soils, As release to solution was highly dependent on pH. Carbonation of these alkaline solutions by dissolution of atmospheric CO2 reduced pH, which resulted in a decrease of aqueous As concentrations over time. However, this did not result in complete removal of aqueous As in any of the experiments. Carbonation did not occur in anaerobic experiments and pH remained high. Aqueous As concentrations initially increased in all the anaerobic red mud amended experiments, and then remained relatively constant as the systems became more reducing, both XANES and HPLC-ICP-MS showed that no As reduction processes occurred and that only As(V) species were present. These experiments show that there is the potential for increased As mobility in soil-water systems affected by red mud addition under both aerobic and anaerobic conditions.

Original languageEnglish
Pages (from-to)268-277
Number of pages10
JournalApplied Geochemistry
Volume51
DOIs
Publication statusPublished - Dec 1 2014

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Aluminum Oxide
bauxite
redox conditions
Arsenic
mobilization
arsenic
mud
Soils
soil
Experiments
Carbonation
experiment
Suspensions
Biogeochemistry
arsenate
Water
Poisons
Tailings
Hazardous materials spills
soil water

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution
  • Geochemistry and Petrology

Cite this

Lockwood, C. L., Mortimer, R. J. G., Stewart, D. I., Mayes, W. M., Peacock, C. L., Polya, D. A., ... Burke, I. T. (2014). Mobilisation of arsenic from bauxite residue (red mud) affected soils: Effect of pH and redox conditions. Applied Geochemistry, 51, 268-277. https://doi.org/10.1016/j.apgeochem.2014.10.009

Mobilisation of arsenic from bauxite residue (red mud) affected soils : Effect of pH and redox conditions. / Lockwood, Cindy L.; Mortimer, Robert J G; Stewart, Douglas I.; Mayes, William M.; Peacock, Caroline L.; Polya, David A.; Lythgoe, Paul R.; Lehoux, Alizée P.; Gruiz, K.; Burke, Ian T.

In: Applied Geochemistry, Vol. 51, 01.12.2014, p. 268-277.

Research output: Contribution to journalArticle

Lockwood, CL, Mortimer, RJG, Stewart, DI, Mayes, WM, Peacock, CL, Polya, DA, Lythgoe, PR, Lehoux, AP, Gruiz, K & Burke, IT 2014, 'Mobilisation of arsenic from bauxite residue (red mud) affected soils: Effect of pH and redox conditions', Applied Geochemistry, vol. 51, pp. 268-277. https://doi.org/10.1016/j.apgeochem.2014.10.009
Lockwood, Cindy L. ; Mortimer, Robert J G ; Stewart, Douglas I. ; Mayes, William M. ; Peacock, Caroline L. ; Polya, David A. ; Lythgoe, Paul R. ; Lehoux, Alizée P. ; Gruiz, K. ; Burke, Ian T. / Mobilisation of arsenic from bauxite residue (red mud) affected soils : Effect of pH and redox conditions. In: Applied Geochemistry. 2014 ; Vol. 51. pp. 268-277.
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