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| Titel |
High-resolution measurement of nitrous oxide in the Elbe estuary under hypoxia: Hot-spots of biological N2O production |
| VerfasserIn |
Lisa Brase, Ralf Lendt, Tina Sanders, Kirstin Dähnke |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124613
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| Publikation (Nr.) |
 EGU/EGU2016-4072.pdf |
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| Zusammenfassung |
| Nitrous oxide (N2O) is one of the most important greenhouse gases. Its global warming
potential exceeds that of CO2 by a factor of ∼300. Estuaries, being sites of intense biological
N-turnover, are one of the major natural sources of N2O emissions.
On two ship cruises in April and June 2015, concentrations of N2O were measured in the
surface water using equilibrator laser based on-line measurements. Based on these
high-resolution N2O profiles along the Elbe estuary, N2O saturation and N2O-fluxes between
surface water and air were calculated. Additionally, DIN concentrations and dual stable
isotopes of nitrate (δ15N and δ18O) were analyzed.
Concentration and water-to-air fluxes of N2O were highest in the Hamburg port region
and dropped quickly further downstream. Highest water-to-air fluxes were up to 800μM/m2/d
and 1600μM/m2/d in April and in June, respectively. Downstream of the port region, an N2O
oversaturation of 150-200% was estimated over the entire estuary, with saturation
approaching equilibrium (96-100%) only in the North Sea region. N2O production was much
higher in June than in April 2015, likely coupled to lower oxygen saturation in the water
column in June.
Based on these measurements, the port of Hamburg region was identified as a hot-spot of
N2O production. High N2O concentration and depleted values of nitrate isotopes suggest that
nitrification is a significant source of N2O in the estuary, especially at low oxygen
concentration. In the Elbe estuary, hypoxia obviously drastically increased the emissions of
the greenhouse gas N2O. |
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