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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http://urn.fi/URN:NBN:fi-fe2022050532796 http://hdl.handle.net/10138/343323

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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 167 (2022), 108598, ISSN 0038-0717. https://doi.org/10.1016/j.soilbio.2022.108598

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Title: Kinetics of arsenic and antimony reduction and oxidation in peatlands treating mining-affected waters: Effects of microbes, temperature, and carbon substrate
Author: Kujala, Katharina; Laamanen, Tiina; Khan, Uzair Akbar; Besold, Johannes; Planer-Friedrich, Britta
Contributor organization: Suomen ympäristökeskus
The Finnish Environment Institute
Publisher: Elsevier BV
Date: 2022
Language: en
Belongs to series: Soil Biology and Biochemistry
ISSN: 0038-0717
DOI: https://doi.org/10.1016/j.soilbio.2022.108598
URI: http://urn.fi/URN:NBN:fi-fe2022050532796
http://hdl.handle.net/10138/343323
Abstract: 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.
Description: Highlights • Peatland microbes catalyze oxidation and reduction of arsenic and antimony species. • Microbial As/Sb reduction is crucial for efficient contaminant removal in peatlands. • Temperature strongly affects microbial arsenic and antimony turnover rates. • Removal in winter possible due to low concentrations and long water residence times.
Subject: biokemia
mikrobit
aineenvaihdunta
arseeni
antimoni
hapetus-pelkistysreaktio
tuvemaat
saasteet
poistaminen
Subject (yso): arsenic
antimony
peatlands
mining-affected waters
cold climate
ecophysiology
pollutants
Rights: CC BY 4.0


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