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Denitrification and DNRA at the Baltic Sea oxic–anoxic interface : Substrate spectrum and kinetics

Bonaglia, Stefano LU ; Klawonn, Isabell; De Brabandere, Loreto; Deutsch, Barbara; Thamdrup, Bo and Brüchert, Volker (2016) In Limnology and Oceanography 61(5). p.1900-1915
Abstract

The dependence of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) on different electron donors was tested in the nitrate-containing layer immediately below the oxic–anoxic interface (OAI) at three stations in the central anoxic basins of the Baltic Sea. Additionally, pathways and rates of fixed nitrogen transformation were investigated with 15N incubation techniques without addition of donors. Denitrification and anammox were always detected, but denitrification rates were higher than anammox rates. DNRA occurred at two sites and rates were two orders of magnitude lower than denitrification rates. Separate additions of dissolved organic carbon and sulfide stimulated rates without time lag indicating... (More)

The dependence of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) on different electron donors was tested in the nitrate-containing layer immediately below the oxic–anoxic interface (OAI) at three stations in the central anoxic basins of the Baltic Sea. Additionally, pathways and rates of fixed nitrogen transformation were investigated with 15N incubation techniques without addition of donors. Denitrification and anammox were always detected, but denitrification rates were higher than anammox rates. DNRA occurred at two sites and rates were two orders of magnitude lower than denitrification rates. Separate additions of dissolved organic carbon and sulfide stimulated rates without time lag indicating that both organotrophic and lithotrophic bacterial populations were simultaneously active and that they could carry out denitrification or DNRA. Manganese addition stimulated denitrification and DNRA at one station, but it is not clear whether this was due to a direct or indirect effect. Ammonium oxidation to nitrite was detected on one occasion. During denitrification, the production of nitrous oxide (N2O) was as important as dinitrogen (N2) production. A high ratio of N2O to N2 production at one site may be due to copper limitation, which inhibits the last denitrification step. These data demonstrate the coexistence of a range of oxidative and reductive nitrogen cycling processes at the Baltic OAI and suggest that the dominant electron donor supporting denitrification and DNRA is organic matter. Organotrophic denitrification is more important for nitrogen budgets than previously thought, but the large temporal variability in rates calls for long-term seasonal studies.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Limnology and Oceanography
volume
61
issue
5
pages
16 pages
publisher
ASLO
external identifiers
  • scopus:84978120575
  • wos:000383621800025
ISSN
1939-5590
DOI
10.1002/lno.10343
language
English
LU publication?
yes
id
9d4cdbdf-cea5-4062-9f4d-db9be6908515
date added to LUP
2016-11-29 10:14:03
date last changed
2017-10-29 04:54:40
@article{9d4cdbdf-cea5-4062-9f4d-db9be6908515,
  abstract     = {<p>The dependence of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) on different electron donors was tested in the nitrate-containing layer immediately below the oxic–anoxic interface (OAI) at three stations in the central anoxic basins of the Baltic Sea. Additionally, pathways and rates of fixed nitrogen transformation were investigated with <sup>15</sup>N incubation techniques without addition of donors. Denitrification and anammox were always detected, but denitrification rates were higher than anammox rates. DNRA occurred at two sites and rates were two orders of magnitude lower than denitrification rates. Separate additions of dissolved organic carbon and sulfide stimulated rates without time lag indicating that both organotrophic and lithotrophic bacterial populations were simultaneously active and that they could carry out denitrification or DNRA. Manganese addition stimulated denitrification and DNRA at one station, but it is not clear whether this was due to a direct or indirect effect. Ammonium oxidation to nitrite was detected on one occasion. During denitrification, the production of nitrous oxide (N<sub>2</sub>O) was as important as dinitrogen (N<sub>2</sub>) production. A high ratio of N<sub>2</sub>O to N<sub>2</sub> production at one site may be due to copper limitation, which inhibits the last denitrification step. These data demonstrate the coexistence of a range of oxidative and reductive nitrogen cycling processes at the Baltic OAI and suggest that the dominant electron donor supporting denitrification and DNRA is organic matter. Organotrophic denitrification is more important for nitrogen budgets than previously thought, but the large temporal variability in rates calls for long-term seasonal studies.</p>},
  author       = {Bonaglia, Stefano and Klawonn, Isabell and De Brabandere, Loreto and Deutsch, Barbara and Thamdrup, Bo and Brüchert, Volker},
  issn         = {1939-5590},
  language     = {eng},
  month        = {09},
  number       = {5},
  pages        = {1900--1915},
  publisher    = {ASLO},
  series       = {Limnology and Oceanography},
  title        = {Denitrification and DNRA at the Baltic Sea oxic–anoxic interface : Substrate spectrum and kinetics},
  url          = {http://dx.doi.org/10.1002/lno.10343},
  volume       = {61},
  year         = {2016},
}