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| Titel |
Riverine GHG emissions: one year of CO2, 13CO2 and CH4 flux measurements on Vistula river in Krakow, southern Poland |
| VerfasserIn |
Alina Jasek, Przemysław Wachniew, Miroslaw Zimnoch |
| 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 |
250080956
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| Zusammenfassung |
| Terrestrial surface waters are generally considered to be sources of carbon dioxide and
methane, because respiration of organic matter via aerobic and anaerobic pathways causes
supersaturation of surface waters with respect to CO2 and CH4, respectively. In rivers, these
processes are influenced by such anthropogenic factors as changes of land-use, wastewater
and alteration of river channels.
The research object is Vistula, the largest Polish river. It has the length of 1047 km and
annual runoff of 6.2x1010m3. The urban section of Vistula in Krakow receives large amounts
of organic matter from highly urbanized catchment and point discharges of urban waste
waters within the city limits. The river was sampled regularly at three points: the entrance to
the city, the center and the point where Vistula leaves the agglomeration. A floating
chamber coupled with Picarro G2101-i analyzer was applied to quantify CO2, 13CO2
and CH4 fluxes leaving the surface of the river. A floating chamber was equipped
with sensors to measure air pressure, temperature and humidity inside the chamber
and the temperature of water. The chamber was equipped with a set of floats and
an anchor. The measurements started in October 2011, and were repeated with
approximately monthly frequency. Physicochemical properties of water (temperature,
conductivity, pH, CO2 partial pressure over the water surface and alkalinity) were also
measured during each measurement campaign. In addition, at each site short-term
variability of the measured fluxes was also investigated. Additionally, short-term
variability of the measured fluxes of CO2, 13CO2 and CH4 were performed in all three
sites.
The results indicate that fluxes of CO2 released from the river are comparable with the
soil emissions of this gas measured in Krakow area. The δ13CO2 signature of riverine CO2
flux allowed to identify decomposition of C3 organic matter as the major source of this gas.
No distinct seasonal variability of the CO2 emission and its stable isotope composition was
observed, suggesting that main factors controlling emission of CO2 from the river
are not related to meteorological conditions as well as to physicochemical water
parameters.
It turned out that ebullition of methane from the river bed contributes significantly to the
overall flux of CH4. The waterborne flux of CH4, after correcting for ebullition remained
positive (in the order of 3-20 mmol m-2h-1, depending on the site), which shows that urban
river is an important emitter of this gas.
Acknowledgement: This work is supported by the Ministry of Science and Higher
Education (project No. 817.N-COST/2010/0). |
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