 |
| Titel |
Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea |
| VerfasserIn |
B. Veuger, A. Pitcher, S. Schouten, J. S. Sinninghe Damsté, J. J. Middelburg |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 3 ; Nr. 10, no. 3 (2013-03-14), S.1775-1785 |
| Datensatznummer |
250018154
|
| Publikation (Nr.) |
 copernicus.org/bg-10-1775-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
Nitrification and the associated growth of autotrophic nitrifiers, as well
as the contributions of bacteria and Thaumarchaeota to total autotrophic
C-fixation by nitrifiers were investigated in the Dutch coastal North Sea
from October 2007 to March 2008. Rates of nitrification were determined by
incubation of water samples with 15N-ammonium and growth of autotrophic
nitrifiers was measured by incubation with 13C-DIC (dissolved inorganic carbon) in the presence
and absence of nitrification inhibitors (nitrapyrin and chlorate) in
combination with compound-specific stable isotope (13C) analysis of
bacterial and Thaumarchaeotal lipid biomarkers. Net nitrification during
the sampling period was evident from the concentration dynamics of ammonium,
nitrite and nitrate. Measured nitrification rates were high (41–221 nmol N L−1 h−1). Ammonium assimilation was always substantially lower
than nitrification – with nitrification on average contributing 89%
(range 73–97%) to total ammonium consumption.
13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly
reduced by the nitrification inhibitors (27–95 %). The inhibitor-sensitive
13C-PLFA (phospholipid-derived fatty acid) pool was dominated by the common PLFAs 16:0, 16:1ω7c
and 18:1ω7c throughout the whole sampling period and occasionally
also included the polyunsaturated fatty acids 18:2ω6c and
18:3ω3. 13C-DIC fixation activity of the nitrifying bacteria
was much higher than that of the nitrifying Thaumarchaeota throughout the
whole sampling period, even during the peak in Thaumarchaeotal abundance and
activity. This suggests that the contribution of autotrophic Thaumarchaeota
to nitrification during winter in the coastal North Sea may have been
smaller than expected from their gene abundance (16S rRNA and amoA (ammonia
monooxygenase)). These results emphasize the importance of direct measurements of the actual
activity of bacteria and Thaumarchaeota, rather than abundance measurements
only, in order to elucidate their biogeochemical importance. The ratio
between rates of nitrification versus DIC fixation by bacterial nitrifiers
was higher or even much higher than typical values for autotrophic
nitrifiers, indicating that little DIC was fixed relative to the amount of
energy that was generated by nitrification. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|