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| Titel |
Apportionment of carbon dioxide over central Europe: insights from combined measurements of atmospheric CO2 mixing ratios and carbon isotope composition |
| VerfasserIn |
M. Zimnoch, D. Jelen, M. Galkowski, T. Kuc, J. Necki, L. Chmura, Z. Gorczyca, A. Jasek, K. Rozanski |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060870
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| Zusammenfassung |
| The European continent, due to high population density and numerous sources of
anthropogenic CO2 emissions, plays an important role in the global carbon budget.
Nowadays, precise measurements of CO2 mixing ratios performed by both global and
regional monitoring networks, combined with appropriate models of carbon cycle, allow
quantification of the European input to the global atmospheric CO2 load. However,
measurements of CO2 mixing ratios alone cannot provide the information necessary for the
apportionment of fossil-fuel related and biogenic contributions to the total CO2 burden of the
regional atmosphere. Additional information is required, for instance obtained through
measurements of radiocarbon content in atmospheric carbon dioxide. Radiocarbon is a
particularly useful tracer for detecting fossil carbon in the atmosphere on different spatial and
temporal scales.
Regular observations of atmospheric CO2mixing ratios and their isotope compositions
have been performed during the period of 2005-2009 at two sites located in central Europe
(southern Poland). The sites, only ca. 100 km apart, represent two extreme environments with
respect to the extent of anthropogenic pressure: (i) the city of Krakow, representing typical
urban environment with numerous sources of anthropogenic CO2, and (ii) remote mountain
site Kasprowy Wierch, relatively free of local influences. Regular, quasi-continuous
measurements of CO2 mixing ratios have been performed at both sites. In addition,
cumulative samples of atmospheric CO2 have been collected (weekly sampling regime for
Krakow and monthly for Kasprowy Wierch) to obtain mean carbon isotope signature
(14C/12C and 13C/12C ratios) of atmospheric CO2 at both sampling locations. Partitioning of
the local atmospheric CO2 load at both locations has been performed using isotope- and mass
balance approach.
In Krakow, the average fossil-fuel related contribution to the local atmospheric CO2 load
was equal to approximately 3.4%. The biogenic component turned out to be of the same
magnitude. Both components revealed a distinct seasonality, with the fossil-fuel
related component reaching maximum values during winter months and the biogenic
component shifted in phase by ca. 6 months. Seasonality of fossil-fuel related CO2 load
in the local atmosphere is linked with seasonality of local CO2sources, mostly
burning of fossil fuels for heating purposes. Positive values of biogenic component
indicate prevalence of the local respiration and biomass burning processes over local
photosynthesis. Summer maxima of biogenic CO2 component represent mostly
local respiration activity. Direct measurements of soil CO2 fluxes in the Krakow
region showed an approximately 10-fold increase of those fluxes during the summer
months.
Partitioning of the local CO2 budget for Kasprowy Wierch site revealed large differences
in the derived components when compared to urban atmosphere of Krakow: the fossil-fuel
related component was ca. 5 times lower whereas the biogenic component was negative in
summer, pointing to the importance of photosynthetic sink associated with extensive forests
in the neighborhood of the station.
The isotope- and mass balance approach was also used to derive mean monthly 13C
isotope signature of fossil-fuel related CO2 emissions in Krakow. Although the derived
δ13CO2 values revealed large variability, they are confined in the range of 13C isotope
composition being reported for various sources of CO2 emissions in the city (burning of coal
and oil, burning of methane gas, traffic). |
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