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| Titel |
Factors influencing CO2 and CH4 emissions from coastal wetlands in the Liaohe Delta, Northeast China |
| VerfasserIn |
L. Olsson, S. Ye, X. Yu, M. Wei, K. W. Krauss, H. Brix |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 16 ; Nr. 12, no. 16 (2015-08-20), S.4965-4977 |
| Datensatznummer |
250118069
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| Publikation (Nr.) |
 copernicus.org/bg-12-4965-2015.pdf |
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| Zusammenfassung |
| Many factors are known to influence greenhouse gas emissions from coastal
wetlands, but it is still unclear which factors are most important under
field conditions when they are all acting simultaneously. The objective of
this study was to assess the effects of water table, salinity, soil
temperature and vegetation on CH4 emissions and ecosystem respiration
(Reco) from five coastal wetlands in the Liaohe Delta, Northeast China:
two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy.
Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas
the Phragmites wetlands and the rice paddy were net CH4 sources emitting 1.2–6.1 g CH4 m−2 yr−1.
The Phragmites wetlands emitted the most CH4 per
unit area and the most CH4 relative to CO2. The main controlling
factors for the CH4 emissions were water table, temperature, soil
organic carbon and salinity. The CH4 emission was accelerated at high
and constant (or managed) water tables and decreased at water tables below
the soil surface. High temperatures enhanced CH4 emissions, and
emission rates were consistently low (< 1 mg CH4 m−2 h−1) at soil temperatures < 18 °C. At salinity levels
> 18 ppt, the CH4 emission rates were always low (< 1 mg CH4 m−2 h−1) probably because methanogens were
out-competed by sulphate-reducing bacteria. Saline Phragmites wetlands can, however,
emit significant amounts of CH4 as CH4 produced in deep soil
layers are transported through the air-space tissue of the plants to the
atmosphere. The CH4 emission from coastal wetlands can be reduced by
creating fluctuating water tables, including water tables below the soil
surface, as well as by occasional flooding by high-salinity water. The
effects of water management schemes on the biological communities in the
wetlands must, however, be carefully studied prior to the management in
order to avoid undesirable effects on the wetland communities. |
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