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Impact of photo-chemical processing of DOC on the bacterioplankton respiratory quotient in aquatic ecosystems

  • Lina Allesson
  • Lena Ström
  • Martin Berggren
Publishing year: 2016-07-28
Language: English
Pages: 7538-7545
Publication/Series: Geophysical Research Letters
Volume: 43
Issue: 14
Document type: Journal article
Publisher: American Geophysical Union (AGU)

Abstract english

Many studies assume a respiratory quotient (RQ = molar ratio of CO2 produced to O2 consumed) close to 1 when calculating bacterioplankton respiration. However, evidence suggests that RQ depends on the chemical composition of the respired substrate pool that may be altered by photo-chemical production of oxygen-rich substrates, resulting in elevated RQs. Here we conducted a novel study of the impact of photo-chemical processing of dissolved organic carbon (DOC) on RQ. We monitored the bacterial RQ in bioassays of both ultraviolet light irradiated and non-irradiated humic lake water, using optic gas-pressure sensors. In the experimentally irradiated samples the average RQ value was significantly higher (3.4-3.5 [± 0.4 s.e.]) than that in the dark controls (1.3 [± 0.1 s.e.]). Our results show that the RQ is systematically higher than 1 when the bacterial metabolism in large part is based on photo-products. By assuming an RQ of 1, bacterioplankton respiration in freshwater ecosystems may be greatly underestimated.


  • Earth and Related Environmental Sciences


  • ISSN: 1944-8007
E-mail: lena [dot] strom [at] nateko [dot] lu [dot] se


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Lund University
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