Isotopic composition of the major greenhouse gases (CH4, CO2) in the atmosphere of southern Poland

Multi-year investigations of concentration and isotopic composition of atmospheric CO2 and CH4 in the southern Poland are discussed. The results obtained for Cracow station reflect a strong anthropopression (combustion and fossil fuels) while these for the Kasprowy Wierch station are characteristic for the central Europe and are considered as reference values. Parallel measurements of CO2 and CH4 concentrations at Kasprowy Wierch and at Cracow revealed similar values for spot samplings performed during active vertical mixing of the low atmosphere. However, the mean values, and the diurnal amplitudes are remarkably different at this points. Analysing the observed correlation of isotopic composition and the concentration one can asses the mean isotopic composition of the local source and try to identify it. Detailed analysis of the carbon isotopic composition of CO2 enables separation of the biogenic and anthropogenic component. Similar analysis of the atmospheric CH4 at Cracow area inevquivocally pointing to leakages in the local gas network as a main source of abnormally high methane concentration in ambient air. The δ 13C value for the local anthropogenic sources of methane was found to be between -53 and -23 permille (varying input of different fossil fuels). Seasonal fluctuations of the CO2 concentration at the Kasprowy Wierch station are between 355 ppm in summer and 380 in winter what recognised as background level in this part of Europe. The 14C and 13C atmospheric content are matching the reference values for Europe, however reveal higher seasonal fluctuations. The CH4 mean concentration at the Kasprowy Wierch is ca. 1850 ppb without noticeable seasonal changes. (author)