We discuss results of a complex shipborne research of the spatial distribution of the aerosol fields conducted by means of laser sensing and in situ measurements. Based on direct sampling of aerosol followed by chromatographic determination of concentration of individual fractions of polycyclic aromatic hydrocarbons (PAH), we have mapped the concentration distributions over Lake Baikal. It was found that the mean concentrations of the PAH sum were close to the background ones with their spatial distribution being rather nonuniform. Simultaneous analysis of 2-D spatial sections of aerosol fields acquired with lidar has revealed some characteristic tendencies in spatial fluctuations of these parameters. In addition to instrumental investigations, model calculations of the PAH distributions were conducted based on numerical solution of the spatial nonstationary semiempirical equation of the turbulent diffusion of admixtures. The comparison with the experiment has shown the calculated concentrations to be close to the measured ones.