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| Titel |
Nitrification and its oxygen consumption along the turbid Changjiang River plume |
| VerfasserIn |
Sung-Yun Hsiao, Ting-Chang Hsu, Jing-Yu Terence Yang, Jing-Wen Liu, Xia-Bing Xie, Yao Zhang, Shih-Chieh Hsu, Jing Lin, Minhan Dai, Shuh-Ji Kao |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250071953
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| Zusammenfassung |
| Enhanced nutrients and organic material export from rivers cause severe oxygen
consumption, subsequently, hypoxia at the land-ocean boundary resulting in disruption of
coastal ecosystem and potentially increasing emission of greenhouse gas. Nitrification is
thought to be one of the important oxygen consuming process and the dominant N2O
contributor in aquatic environment. By using stable isotope tracer method we determine the
nitrification rate (bulk water and >3 μm particle free) and N2O production rate along
Changjiang River plume in 2011 August. Community respiration rate was measured to
identify the role of nitrification in oxygen consumption. Total suspended material, nutrients,
dissolved oxygen, and particulate iron /manganese(acid-leacheable) were measured to
explore controlling factors for nitrification. The bulk nitrification rate ranged from
undetectable to 4586 nmol L-1 day-1 and peaked at inter salinity (S=29). The
nitrous oxide was produced only in river mouth, but the production rate was not high
enough to support the water column nitrous oxide concentration. Results implied
that the water column nitrification was not the main source of nitrous oxide. The
determination of nitrification rate and β-proteobacterial AmoA gene abundance on particle
or particle-free fraction showed that nitrification preferred to occur on particles
in turbid region. Moreover, the amount of reactive Fe/Mn on suspended particles
was found linearly correlated to nitrification rate separately in inner shelf and river
mouth. In previous study in sediment Fe/Mn were proposed to be alternative oxidant
when oxygen was exhausted. However, in this survey we didn’t observe hypoxia.
In inner shelf region, the estimated oxygen consumption by nitrification ranged
from 0.4% to 317% of total community respiration.The excess oxygen demand
indicates the oxygen might not be the only oxidant. Stoichiometrical calculation
suggests reactive Fe was sufficient to support nitrification along all regions of the
plume. This is the first report to reveal the relationship between reactive Fe/Mn and
measured nitrification rate and oxygen consumption rate in aerobic water column. |
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