Stabilising metal(loid)s in soil with iron and aluminium-based products: microbial, biochemical and plant growth impact

J Environ Manage. 2014 Jun 15:139:146-53. doi: 10.1016/j.jenvman.2014.02.024. Epub 2014 Mar 29.

Abstract

Four iron and aluminium-based products, including red mud (RM), hematite (Fe2O3), an iron-rich water treatment residual (Fe-WTR) and amorphous Al hydroxide (Al-OH), were evaluated for their effectiveness at stabilising As and heavy metals (i.e. Cd, Cu, Pb, Zn) in a circumneutral contaminated soil [As (2105 mg kg(-1)), Cd (18 mg kg(-1)), Cu (264 mg kg(-1)), Pb (710 mg kg(-1)), Zn (522 mg kg(-1))]. Treatment impacts on soil microbial and biochemical features (i.e. microbial biomass-C, microbial counts, 16S rRNA PCR-TTGE of culturable bacteria, dehydrogenase, urease and β-glucosidase activity, Biolog derived parameters-AWCD and richness) as well as bean (Phaseolus vulgaris) and wheat (Triticum vulgare) growth were also assessed. After 6 months equilibration, all the amendments (application rate 3% w/w) but RM reduced labile As while only Al-OH reduced the concentration of water-soluble heavy metals. Despite the highest bioavailability of contaminants, most of the soil microbial and biochemical features monitored (i.e. microbial biomass-C, total bacterial counts, dehydrogenase activity and AWCD) were significantly higher in the RM-soil. Bean germination was completely inhibited in RM-soil while wheat growth was similar to that of the control. The Al-OH treatment was best overall, promoting microbial abundance, diversity and activity while increasing bean and wheat growth and reducing As accumulated in plant shoots. Results suggest that Al-OH is a suitable candidate for field evaluations while the use of RM in the remediation of circumneutral or subalkaline contaminated soils should be reconsidered.

Keywords: Arsenic-polluted soil; Iron and aluminium-based products; Plant growth; Sequential extraction; Soil enzyme activity; Soil microbial community.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Hydroxide / chemistry*
  • Aluminum Hydroxide / toxicity
  • Arsenic / chemistry*
  • Bacterial Load
  • Biomass
  • Ferric Compounds / chemistry*
  • Ferric Compounds / toxicity
  • Iron / chemistry*
  • Iron / toxicity
  • Metals, Heavy / chemistry*
  • Phaseolus / drug effects
  • Phaseolus / growth & development
  • RNA, Ribosomal, 16S / analysis
  • Soil Microbiology
  • Soil Pollutants / chemistry*
  • Triticum / drug effects
  • Triticum / growth & development

Substances

  • Ferric Compounds
  • Metals, Heavy
  • RNA, Ribosomal, 16S
  • Soil Pollutants
  • ferric oxide
  • Aluminum Hydroxide
  • Iron
  • Arsenic