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| Titel |
Sources and transport of δ¹⁴C in CO2 within the Mexico City Basin and vicinity |
| VerfasserIn |
S. A. Vay, S. C. Tyler, Y. Choi, D. R. Blake, N. J. Blake, G. W. Sachse, G. S. Diskin, H. B. Singh |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 14 ; Nr. 9, no. 14 (2009-07-27), S.4973-4985 |
| Datensatznummer |
250007527
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| Publikation (Nr.) |
 copernicus.org/acp-9-4973-2009.pdf |
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| Zusammenfassung |
| Radiocarbon samples taken over Mexico City and the surrounding region during
the MILAGRO field campaign in March 2006 exhibited an unexpected
distribution: (1) relatively few samples (23%) were below the North
American free tropospheric background value (57±2‰) despite the fossil
fuel emissions from one of the world's most highly polluted environments;
and (2) frequent enrichment well above the background value was observed.
Correlate source tracer species and air transport characteristics were
examined to elucidate influences on the radiocarbon distribution. Our
analysis suggests that a combination of radiocarbon sources biased the
"regional radiocarbon background" above the North American value thereby
decreasing the apparent fossil fuel signature. Likely sources include the
release of 14C-enhanced carbon from bomb 14C sequestered in plant
carbon pools via the ubiquitous biomass burning in the region as well as the
direct release of radiocarbon as CO2 from other "hot"
sources. Plausible perturbations from local point "hot" sources
include the burning of hazardous waste in cement kilns; medical waste
incineration; and emissions from the Laguna Verde Nuclear Power Plant. These
observations provide insight into the use of Δ14CO2 to
constrain fossil fuel emissions in the megacity environment, indicating that
underestimation of the fossil fuel contribution to the CO2 flux is
likely wherever biomass burning coexists with urban emissions and is
unaccounted for as a source of the elevated CO2 observed above local
background. Our findings increase the complexity required to quantify fossil
fuel-derived CO2 in source-rich environments characteristic of
megacities, and have implications for the use of Δ14CO2
observations in evaluating bottom-up emission inventories and their
reliability as a tool for validating national emission claims of CO2
within the framework of the Kyoto Protocol. |
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