The problem of identification is very actual, because its solution makes it possible to determine the contribution of different sources - the institution, the city, the country - to the air pollution at a given point. The paper describes the formalized approach that, on the basis of experimental data, allows the determination of the contribution of different sources to the pollution of snow cover of a point-receptor. The solution technique is based on the minimization of discrepancies between measured and calculated data. Methods of mathematical programming (the Lagrange multiplier method, the affine scaling method) were used. Polycyclic aromatic hydrocarbons (PAH) are considered as the most effective tracers. The distribution of reference PAH concentrations simplifies considerably the problem and allows the least squares method to be used.