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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
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
organization
publishing date
type
Contribution to journal
publication status
epub
subject
in
Geophysical Research Letters
publisher
American Geophysical Union
external identifiers
  • Scopus:84982103500
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
2016-11-09 14:39:13
@misc{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        = {06},
  publisher    = {ARRAY(0xa348880)},
  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},
  year         = {2016},
}