THE ANALYSIS OF ATMOSPHERIC METHANE CONCENTRATION IN THE AREAL OF CLUJ C.Cuna, P. Ardelean, Stela Cuna National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania We measured the atmospheric methane concentrations from different areas, situated nearby localities, in the surroundings of Cluj-Napoca. For the analysis, we used two types of single focusing mass spectrometer, a double focusing mass spectrometer Finnigan - MAT-311 type and a GCL-90 type gaschromatograph. Our data will contribute to the completion of the existing ones, in view of the realization of a mathematical model, for a correct prediction of the atmospheric methane concentration variations and the appreciation of the contribution of different sources of atmospheric methane. Some methods of prelevation and enrichment in methane of the samples, in view of their preparation for the analysis, were imagined. To measure the atmospheric methane concentration we prepared several useful standards, especially for gas-chromatographic analysis. The isotopic signature of the methane from different sources will be given. These data are useful in the origine elucidation of the atmospheric methane at the ecosystem level. In the last time, many forest and field fires were produced, and, consequently the concentration of the atmospheric methane has changed, by biomass burning, at last on reduced areals. The transport of the methan by atmospheric streams in East-european area can be monitored by correlation to the measurements realized in different countries. These measurement can be extended also to other gases of interest as Nox, N2O, CO. We began to make weekly determinations, to monitor the seasonal variations of atmospheric methane concentration.