CO2 concentrations and δ13C (CO2) values in monthly sets of air samples from downtown Parma and the Parma and Taro river valleys, Emilia-Romagna, Italy†

Abstract

Monthly sets of discrete air samples were collected from September 2004 to June 2005 in the town of Parma, along North-South and East-West runs (8 plus 8 samples), using four-litre Pyrex flasks. The CO2 concentrations and δ13C values were determined on these samples with the aim of evaluating quantitatively the contribution of domestic heating to the winter atmospheric CO2 pollution in downtown Parma by comparing autumn and spring atmospheric values with winter values. After separation of CO2 from the other air gases in the laboratory, the CO2 concentrations were calculated from the intensity of the 12C16O ion beam in the mass spectrometer, after calibration with artificial air samples whose CO2 concentration was very carefully determined by the Monte Cimone Observatory (Sestola, Modena, Italy). The reproducibility of these measurements was of ∼±0.4 % and, consequently, the most probable error is not higher than±2–3 ppmv and does not affect the magnitude of the gradients between different samples. The standard deviation of δ13C measurements ranges from±0.02 to ±0.04 ‰ (1σ). The results suggest that the contribution of domestic heating to atmospheric CO2 pollution is almost negligible in the case of ground level atmosphere, where the main CO2 pollution is essentially related to the heavy car traffic. This is probably because of the fact that the gases from the domestic heating systems are discharged tens of metres above ground level at a relatively high temperature so that they rise quickly to the upper atmospheric layers and are then displaced by air masses dynamics. Revised version of a paper presented at the VIII IsotopeWorkshop of the European Society for Isotope Research (ESIR), 25–30 June, 2005, Leipzig-Halle, Germany. Monthly sets of discrete air samples were also collected from October 2004 to June 2005 along North-South runs from the town of Parma to the Apennine ridge following the Parma and the Taro river valleys (8 samples and 7 samples per set, respectively) and measured using the same technique. The aim of this study was the comparison between the town samples, the plain country samples and the samples collected on the northern slope of the Apennines. The results reveal huge variations of both CO2 concentration and δ13C through space and time, some of which can be reasonably explained whereas others are rather difficult to understand. The sets of values are discussed and various hypotheses are suggested.