 |
| Titel |
Nitrification and its oxygen consumption along the turbid Chang Jiang River plume |
| VerfasserIn |
S. S.-Y. Hsiao, T.-C. Hsu, J.-W. Liu, X. Xie, Y. Zhang, J. Lin, H. Wang, J.-Y. T. Yang, S.-C. Hsu, M. Dai, S.-J. Kao |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 7 ; Nr. 11, no. 7 (2014-04-14), S.2083-2098 |
| Datensatznummer |
250117359
|
| Publikation (Nr.) |
 copernicus.org/bg-11-2083-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Nitrification is a series of processes that oxidizes ammonia to nitrate,
which contributes to hypoxia development in coastal oceans, especially in
eutrophicated regions. The nitrification rate of bulk water (NRb)
and particle free water (NRpf, particle > 3 μm
eliminated) were determined along the Chang Jiang River plume in August 2011
by nitrogen isotope tracer technique. Measurements of dissolved oxygen (DO),
community respiration rate (CR), nutrients, dissolved organic nitrogen (DON),
total suspended matter (TSM), particulate organic carbon/nitrogen
(POC / PON), acid-leachable iron and manganese on suspended particles and
both archaeal and β-proteobacterial ammonia monooxygenase subunit A
gene (amoA) abundance on size-fractioned particles
(> 3 μm and 0.22–3 μm) were conducted. The
NRb ranged from undetectable up to
4.6 μmol L−1 day−1, peaking at a salinity of
~ 29. NRb values were positively correlated with ammonium
concentration, suggesting the importance of substrate in nitrification. In
the river mouth and the inner plume, NRb was much higher than
NRpf, indicating that the nitrifying microorganism is mainly
particle associated, which was supported by its significant correlation with
amoA gene abundance and TSM concentration. The estimated oxygen
demands of nitrification accounted for 0.32 to 318% of CR, in which
50% samples demanded more oxygen than that predicted by by the Redfield
model (23%), indicating that oxygen might not be the sole oxidant though
DO was sufficient (> 58 μmol kg−1) throughout the
observation period. The excess nitrification-associated oxygen demand (NOD)
showed a tendency to occur at lower DO samples accompanied by higher
acid-leachable Fe / Mn, which implied reactive Fe3+ / Mn4+ may
play a role as oxidant in the nitrification process. Stoichiometric
calculation suggested that reactive Fe on particles was 10 times the oxidant
demand required to complete ammonia oxidation in the entire plume. The
potential involvement of reactive iron and manganese in the nitrification
process in oxygenated water further complicated nitrogen cycling in the
turbid river plume. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|