Skład izotopowy dwutlenku węgla w atmosferze Krakowa
Isotopic composition of carbon dioxide in the atmosphere of Kraków

Summary/Abstract: The elevated concentrations of CO2 observed in Krakow during the cold season are undoubtedlyof anthropogenic origin – mainly the burning of natural gas for heating purposes. The impact of thissource is more visible in winter due to the absence of the photosynthetic activity of the local biosphere.The mean CO2 mixing ratio in summer (June–August) was 10 ppm lower than the one recordedin winter (December–February). This decrease stems from the enhanced activity of the local biosphereand the reduction of anthropogenic CO2 emissions during the warm season. The mean δ13Csignature of the local CO2 source in summer indicates that biospheric and traffic emissions were themain source of excess CO2 concentration observed in the local atmosphere. The role of urban biospherein the local carbon balance became apparent during a long dry period (July–August 2013),when the increase in the observed CO2 concentration was not reflected in the corresponding shift ofthe mean δ13C signature of the local CO2 source. The slowing down of photosynthetic activity lead tothe accumulation of CO2 in the local atmosphere. The observed decreased values of the mean CO2source during winter indicate enhanced contribution of anthropogenic emissions, mainly the burningof natural gas. Isolated episodes of elevated CO2 concentration could be also attributed, via a backwardsair trajectory analysis, to coal burning by local industry (thermal power plant, ironworks).Nevertheless, a vast majority of short-term events of high CO2 concentration that have been observedduring the analyzed period were related to the dynamics of lower atmosphere (build-up anddecay of the inversion layer). In those cases, the increase in CO2 concentration could be traced back toemissions originating in close proximity of the measurement site. An analysis of the events when theCO2 concentration increases were not related to the suppression of vertical mixing of the local atmospherepointed to the local industry as the main source of carbon dioxide.

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