University of Oulu

Katharina Kujala, Tiina Laamanen, Uzair Akbar Khan, Johannes Besold, Britta Planer-Friedrich, Kinetics of arsenic and antimony reduction and oxidation in peatlands treating mining-affected waters: Effects of microbes, temperature, and carbon substrate, Soil Biology and Biochemistry, Volume 167, 2022, 108598, ISSN 0038-0717,

Kinetics of arsenic and antimony reduction and oxidation in peatlands treating mining-affected waters : effects of microbes, temperature, and carbon substrate

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Author: Kujala, Katharina1; Laamanen, Tiina1,2; Khan, Uzair Akbar1;
Organizations: 1Water, Energy and Environmental Engineering Research Unit, University of Oulu, Finland
2Finnish Environment Institute, Freshwater Centre, Oulu, Finland
3Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Germany
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5.6 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-04-19


Arsenic (As) and antimony (Sb) from mining-affected waters are efficiently removed in two treatment peatlands (TPs) in Northern Finland. However, the exact mechanisms behind this removal are not well resolved. Thus, the present study combines results from microcosm experiments and pilot-scale TPs on the effects of microbes, temperature, and carbon substrate to elucidate the role of peat microorganisms in As and Sb removal. The main As and Sb species in TP inflow water are arsenate and antimonate. In peat microcosms, they were quantitatively reduced, however, at rates about 20–400 times lower than previously reported from pure cultures, likely due to excess of other terminal electron acceptors, such as nitrate and sulfate. Addition of the microbial inhibitor sodium azide inhibited reduction, indicating that it is indeed microbially mediated. Arsenite and antimonite (re)oxidation, which is in situ likely limited to upper, oxic peat layers, was likewise observed in peat microcosms. Only for antimonite, oxidation also occurred abiotically, likely catalyzed by humic acids or metals. Process rates increased with increasing temperature, but all processes occurred also at low temperatures. Monitoring of pilot-scale TPs revealed only minor effects of winter conditions (i.e., low temperature and freezing) on arsenic and antimony removal. Formation of methylated oxyarsenates was observed to increase As mobility at the onset of freezing. From different carbon substrates tested, lactate slightly enhanced arsenate reduction and antimonate reduction was stimulated by acetate, lactate, and formate. However, a maximum rate enhancement of only 1.8 times indicates that carbon substrate availability is not the rate-limiting factor in microbial arsenate or antimonate reduction. The collective data indicate that microorganisms catalyze reduction and (re)oxidation of As and Sb species in the TPs, and even though temperature is a major factor controlling microbial As and Sb reduction/(re)oxidation, low inflow concentrations, long water residence times, and the presence of unfrozen peat in lower layers allow for efficient removal also under winter conditions.

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Series: Soil biology & biochemistry
ISSN: 0038-0717
ISSN-E: 1879-3428
ISSN-L: 0038-0717
Volume: 167
Article number: 108598
DOI: 10.1016/j.soilbio.2022.108598
Type of Publication: A1 Journal article – refereed
Field of Science: 1183 Plant biology, microbiology, virology
Funding: Funding for this work was provided by the Academy of Finland (projects 287397 and 322753 awarded to KK) and the University of Oulu. The pilot-scale TPs were built and operated with support provided by the Interreg Nord 2014–2020 program (project “Min-North”). Laboratory analyses at Bayreuth University were funded by the German Research Foundation Grant PL 302/20-1 awarded to BPF.
Academy of Finland Grant Number: 287397
Detailed Information: 287397 (Academy of Finland Funding decision)
322753 (Academy of Finland Funding decision)
Copyright information: © 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (