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

Allesson, Lina ; Ström, Lena LU and Berggren, Martin LU (2016) In Geophysical Research Letters 43(14). p.7538-7545
Abstract
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... (More)
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.
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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Geophysical Research Letters
volume
43
issue
14
pages
8 pages
publisher
American Geophysical Union (AGU)
external identifiers
  • scopus:84982103500
  • wos:000383290200031
ISSN
1944-8007
DOI
10.1002/2016GL069621
language
English
LU publication?
yes
id
a074e787-6543-4a51-9dd5-8a34ebe2d264
date added to LUP
2016-07-05 10:24:27
date last changed
2022-04-16 18:20:14
@article{a074e787-6543-4a51-9dd5-8a34ebe2d264,
  abstract     = {{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.<br/>}},
  author       = {{Allesson, Lina and Ström, Lena and Berggren, Martin}},
  issn         = {{1944-8007}},
  language     = {{eng}},
  month        = {{07}},
  number       = {{14}},
  pages        = {{7538--7545}},
  publisher    = {{American Geophysical Union (AGU)}},
  series       = {{Geophysical Research Letters}},
  title        = {{Impact of photo-chemical processing of DOC on the bacterioplankton respiratory quotient in aquatic ecosystems}},
  url          = {{http://dx.doi.org/10.1002/2016GL069621}},
  doi          = {{10.1002/2016GL069621}},
  volume       = {{43}},
  year         = {{2016}},
}