J. M. Necki

Assessing surface fluxes of CO2 and CH4 in urban environment: a reconnaissance study in Krakow, Southern Poland

Regular observations of atmospheric mixing ratios of CO2 and CH4, combined with sodar measurements of the mixing layer height in the lower troposphere were used to assess night-time surface fluxes of these gases in the urban environment (Krakow, southern Poland). The measurements performed over the 4-yr period (May 2005–May 2009) revealed a distinct seasonality of surface night-time fluxes of CO2, with the minimum of ca. 2 mmol m-2 h-1 during winter months and the maximum of ca. 20 mmol m-2 h-1 observed during summer months. The observed seasonality was induced by the biospheric component (soil respiration) which dominates the measured surface CO2 fluxes during summer months. The surface fluxes of CH4 scatter between ca. 50 and 200 ¼mol m.2 h.1, without clear seasonal trend. Significant flux of CH4 into the atmosphere (mean value over the whole observation period equal to ca. 97 ¼mol m-2 h-1), indicates a presence of relatively strong methane source on the investigated area. This source is linked to methane leakages from the city gas distribution network.

Diurnal variability of delta C-13 and delta O-18 of atmospheric CO2 in the urban atmosphere of Krakow, Poland

This article presents the results of measurements of the isotopic composition and concentration of atmospheric carbon dioxide, performed on air samples from Kraków (Southern Poland) in different seasons of the year. A simple isotope mass balance model has been applied to determine the contributions of different sources of CO2 to the urban atmosphere of Kraków city: the latitudinal/regional background, biospheric contributions and anthropogenic emissions. The calculations show that during the summer and early autumn the dominant contribution to local CO2 peaks is the biosphere, making up to 20% of atmospheric CO2 during the nocturnal temperature inversion in the lower troposphere. During early spring and winter, anthropogenic emissions are the main local source.