Changes of Carbon Isotopes in Atmospheric CO2 of the Kraków Region in the Last Five Years

The Krakow Radiocarbon Laboratory has been measuring isotope composition of atmospheric CO 2 and its natural concentration in the Kraków region for the last five years. We have been sampling on a continuous basis in two-week intervals at ca 20m above ground level, close to the center of Kraków. CO 2 was sorbed while slow pumping atmospheric air through a molecular sieve. After recovery by heating, the CO 2 was converted to benzene and 14 C measured in a liquid scintillation spectrometer. In a small portion of CO 2 δ 13 C was determined in a mass spectrometer. Concentration of CO 2 was assessed by measurement of the volumes of the sorbed CO 2 and the pumped air. A five-year record (1983–1987) reveals a multi-annual linear trend and winter-summer oscillations. Calculated parameters of the regression line (intercept and slope) for the measured δ 14 C, δ 13 C and concentration are: 222 (Jan 1983) and −15.5/yr, −9.57% (Jan 1983) and −0.042/yr, 336ppm (Jan 1983) and 1.4ppm/yr, respectively.