Mobility of arsenic, chromium and copper arising from soil application of stabilised aggregates made from contaminated wood ash

Kerry Mitchell, Eduardo Moreno-Jimenez, Rod Jones, Li Zheng, Lukas Trakal, Rupert Hough, Luke Beesley

Research output: Contribution to journalArticlepeer-review

Abstract

Stabilized cementitious aggregates AG were produced from wood ashes containing ∼10,000 mg kg−1 As, Cr and Cu, then amended to two agricultural pasture soils. Metal(loid) leaching (column tests), mobility (pore water extracts) and uptake to ryegrass was determined, comparing raw ashes with aggregates. Risk modeling was applied to selected data to inform wider discussion of the experimental results. Under rapid leaching (7 h) AG 2 (pre-strengthened with CO2) outperformed AG 1 in suppressing soluble metal(loid) removal. During prolonged leaching (12d) both aggregates were susceptible to mild dissolution/release of metal(loid)s upon acidification. Pore water sampled from the pot test indicated that Cr was generally most mobile, As least so, reduced furthest by AG 2. Risk modelling, based on pot experimental data, demonstrated soil specific accumulation of As in beef muscle and milk, being furthest reduced (compared to the raw ash addition) by AG 2 in soil A, but increased in soil B by the same treatment. The results of this study indicate that a reduction in soluble As, Cr and Cu can be achieved through cementitious aggregation of wood ashes, though the extent is metal(loid) specific when amended to soils. Pre-testing under local soil conditions before field application would be required to ensure that metal(loid) mobility remained suppressed.

Original languageEnglish
Article number122479
Pages (from-to)1-10
Number of pages10
JournalJournal of Hazardous Materials
Volume393
Early online date6 Mar 2020
DOIs
Publication statusPublished - 5 Jul 2020

Keywords

  • Bioavailability
  • Heavy metal leaching
  • Pore water
  • Stabilized aggregate
  • Wood ash

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