Redox-stat bioreactors for elucidating mobilisation mechanisms of trace elements: an example of As-contaminated mining soils

Liwia Rajpert, Andreas Schäffer, Markus Lenz*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)

Abstract

The environmental fate of major (e.g. C, N, S, Fe and Mn) and trace (e.g. As, Cr, Sb, Se and U) elements is governed by microbially catalysed reduction-oxidation (redox) reactions. Mesocosms are routinely used to elucidate trace metal fate on the basis of correlations between biogeochemical proxies such as dissolved element concentrations, trace element speciation and dissolved organic matter. However, several redox processes may proceed simultaneously in natural soils and sediments (particularly, reductive Mn and Fe dissolution and metal/metalloid reduction), having a contrasting effect on element mobility. Here, a novel redox-stat (Rcont) bioreactor allowed precise control of the redox potential (159 ± 11 mV, ~ 2 months), suppressing redox reactions thermodynamically favoured at lower redox potential (i.e. reductive mobilisation of Fe and As). For a historically contaminated mining soil, As release could be attributed to desorption of arsenite [As(III)] and Mn reductive dissolution. By contrast, the control bioreactor (Rnat, with naturally developing redox potential) showed almost double As release (337 vs. 181 μg g−1) due to reductive dissolution of Fe (1363 μg g−1 Fe2+ released; no Fe2+ detected in Rcont) and microbial arsenate [As(V)] reduction (189 μg g−1 released vs. 46 μg g−1 As(III) in Rcont). A redox-stat bioreactor thus represents a versatile tool to study processes underlying mobilisation and sequestration of other trace elements as well.

Original languageEnglish
Pages (from-to)7635–7641
JournalApplied Microbiology and Biotechnology
Volume102
Issue number17
Early online date21 Jun 2018
DOIs
Publication statusPublished - Sep 2018

Keywords

  • Arsenic remediation
  • Redox-stat bioreactor
  • Trace element fate

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