Radiocarbon concentration in the atmosphere and modern tree rings in the Kraków area, southern Poland

New results of radiocarbon concentration in tree rings from the Kraków region covering a growth period of 20 yr have been analyzed, and the relationship between them and ¹⁴C concentrations in the atmospheric CO₂ are described. This enabled assessment of the uptake period for pine trees at the regional climatic conditions. Both sets of data show lower ¹⁴C concentrations than reported for "clean air" at the reference station, indicating a remarkable input of "dead" CO₂ of fossil fuel origin. Using data of carbon dioxide and ¹⁴C concentrations from Schauinsland, summer values of the fossil component (C_f) in carbon dioxide were calculated for the Kraków area. Fitting exponential and linear functions to experimental data, the exchange time was calculated, and expected future ¹⁴C concentration in the atmosphere was estimated.