Miroslaw Zimnoch

Six-year record of atmospheric carbon dioxide and methane at a high-altitude mountain site in Poland

Carbon dioxide and methane observations from the continental mountain station Kasprowy Wierch in the Tatra Mountains, southern Poland, are presented. They cover a six-year period from 1994 to 2000. Significant year-to-year variability of CO2 concentration was observed. The seasonal cycles 1996–1997 were similar, with a peak-to-peak amplitude of the selected and smoothed CO2 record of approximately 20 ppm and no significant increase of the annual mean values. For 1998 and 1999 large increases of the annual mean values by 3.3 and 4.0 ppm per year, respectively, were observed. This increase was accompanied by a reduction of the seasonal amplitude of the smoothed record to approximately 15 ppm in 1998 and 16 ppm in 1999. In 2000 the seasonal amplitude increased again to a value similar as in 1996/1997, whereas the mean annual value remained close to that recorded for 1999. Similar features can also be traced in the selected and smoothed CO2 record for Schauinsland station, Germany, located ca. 1000 km west of Kasprowy Wierch. These similarities strongly suggest that both stations are capturing the same large-scale European phenomena, most probably related to a disturbance of the CO2 cycle by the recent El Niño event. The mean CH4 mixing ratio at Kasprowy Wierch for the period 1996–1999 was about 30 ppb higher than over the Atlantic Ocean, confirming previous observations that the European continent is a net source of methane throughout the year. No significant seasonal cycle of methane has been observed at Kasprowy Wierch. The short-term changes of CO2 and CH4 are strongly correlated during winter months: the average monthly mean slope of the linear relationship between CH4 and CO2 was 10.7 ± 0.3 ppbCH4 per ppmCO2. During summer months this strong correlation breaks down. Diurnal changes of CO2 and CH4 mixing ratios observed at Kasprowy Wierch are typical for continental mountain sites, with a distinct minimum of CO2 during afternoon hours in summer and maximum during winter. For CH4, diurnal cycles have similar shape throughout the year, with a broad maximum during daytime. The mean peak-to-peak amplitudes for summer (July) were 4.5 ppm for CO2 and 30 ppb for CH4, whereas during winter (February) they diminished to 1.5 ppm and 10 ppb, respectively.

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.

Partitioning of atmospheric carbon dioxide over Central Europe: insights from combined measurements of CO 2 mixing ratios and their carbon isotope composition

Regular measurements of atmospheric CO 2 mixing ratios and their carbon isotope composition (13C/12C and 14C/12C ratios) performed between 2005 and 2009 at two sites of contrasting characteristics (Krakow and the remote mountain site Kasprowy Wierch) located in southern Poland were used to derive fossil fuel-related and biogenic contributions to the total CO 2 load measured at both sites. Carbon dioxide present in the atmosphere, not coming from fossil fuel and biogenic sources, was considered ‘background’ CO 2. In Krakow, the average contribution of fossil fuel CO 2 was approximately 3.4%. The biogenic component was of the same magnitude. Both components revealed a distinct seasonality, with the fossil fuel component reaching maximum values during winter months and the biogenic component shifted in phase by approximately 6 months. The partitioning of the local CO 2 budget for the Kasprowy Wierch site revealed large differences in the derived components: the fossil fuel component was approximately five times lower than that derived for Krakow, whereas the biogenic component was negative in summer, pointing to the importance of photosynthetic sink associated with extensive forests in the neighbourhood of the station. While the presented study has demonstrated the strength of combined measurements of CO 2 mixing ratios and their carbon isotope signature as efficient tools for elucidating the partitioning of local atmospheric CO 2 loads, it also showed the important role of the land cover and the presence of the soil in the footprint of the measurement location, which control the net biogenic surface CO 2 fluxes.

Seasonal variability of soil CO2 flux and its carbon isotope composition in Krakow urban area, Southern Poland

As urban atmosphere is depleted of 13CO2, its imprint should be detectable in the local vegetation and therefore in its CO2 respiratory emissions. This work was aimed at characterising strength and isotope signature of CO2 fluxes from soil in urban areas with varying distances from anthropogenic CO2 emissions. The soil CO2 flux and its δ13C isotope signature were measured using a chamber method on a monthly basis from July 2009 to May 2012 within the metropolitan area of Krakow, Southern Poland, at two locations representing different levels of anthropogenic influence: a lawn adjacent to a busy street (A) and an urban meadow (B). The small-scale spatial variability of the soil CO2 flux was also investigated at site B. Site B revealed significantly higher summer CO2 fluxes (by approximately 46 %) than site A, but no significant differences were found between their δ13CO2 signatures.

Quantification of carbon dioxide and methane emissions in urban areas: source apportionment based on atmospheric observations

Anthropogenic emissions of carbon dioxide (CO2) and methane (CH4) in the atmosphere constitute an important component of the related carbon budget. The main source of anthropogenic CO2 is burning of fossil fuels, especially in densely populated areas. Similar emissions of CH4 are associated with the agricultural sector, coal mining, and other human activities, such as waste management and storage and natural gas networks supplying methane to large urban, industrial centers. We discuss several methods aimed at characterizing and quantifying atmospheric loads and fluxes of CO2 and CH4 in Krakow, the second largest city in Poland. The methods are based on atmospheric observations of mixing ratios as well as isotopic composition of the investigated gases. Atmospheric mixing ratios of CO2 and CH4 were measured using gas chromatography (GC) and cavity ring-down spectroscopy (CRDS). The isotopic composition of CO2 and CH4 was analyzed using isotope ratio mass spectrometry (IRMS), accelerator mass spectrometry (AMS), and CRDS techniques. These data, combined with auxiliary information characterizing the intensity of vertical mixing in the lower atmosphere (height of the nocturnal boundary layer [NBL] and atmospheric 222Rn concentration), were further used to quantify emission rates of CO2 and CH4 in the urban atmosphere of Krakow. These methods provide an efficient way of quantifying surface emissions of major greenhouse gases originating from distributed sources, thus complementing the widely used bottom-up methodology based on emission statistics.