A1 Journal article (refereed)
Biogenic Fenton process : A possible mechanism for the mineralization of organic carbon in fresh waters (2021)


Vähätalo, Anssi V.; Xiao, Yihua; Salonen, Kalevi (2021). Biogenic Fenton process : A possible mechanism for the mineralization of organic carbon in fresh waters. Water Research, 188, 116483. DOI: 10.1016/j.watres.2020.116483


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Publication details

All authors or editors: Vähätalo, Anssi V.; Xiao, Yihua; Salonen, Kalevi

Journal or series: Water Research

ISSN: 0043-1354

eISSN: 1879-2448

Publication year: 2021

Volume: 188

Article number: 116483

Publisher: Elsevier

Publication country: United Kingdom

Publication language: English

DOI: http://doi.org/10.1016/j.watres.2020.116483

Open Access: Publication channel is not openly available


Abstract

To explore the mechanisms that mineralize poorly bioavailable natural organic carbon (OC), we measured the mineralization of OC in two lake waters over long-term experiments (up to 623 days) at different pH and iron (Fe) levels. Both the microbial and photochemical mineralization of OC was higher at pH acidified to 4 than at the ambient pH 5 or an elevated pH 6. During 244 days, microbes mineralized up to 60% of OC in the 10-µm filtrates of lake water and more than 27% in the 1-µm filtrates indicating that large-sized microbes/grazers enhance the mineralization of OC. A reactivity continuum model indicated that the acidification stimulated the microbial mineralization of OC especially in the later (>weeks) phases of experiment when the bioavailability of OC was poor. The reactive oxygen species produced by light or microbial metabolism could have contributed to the mineralization of poorly bioavailable OC through photochemical and biogenic Fenton processes catalyzed by the indigenous Fe in lake water. When Fe was introduced to artificial lake water to the concentration found in the study lakes, it increased the densities of bacteria growing on solid phase extracted dissolved organic matter and in a larger extent at low pH 4 than at pH 5. Our results suggest that in addition to the photochemical Fenton process (photo-Fenton), microbes can transfer poorly bioavailable OC into labile forms and CO2 through extracellular Fe-catalyzed reactions (i.e., biogenic Fenton process).


Keywords: carbon cycle; dissolved organic carbon; mineralisation; lakes; microbes; chemical reactions; iron

Free keywords: biogenic Fenton; iron; microbes; organic carbon; reactive oxygen species; reactivity continuum.


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Last updated on 2020-28-10 at 12:11