To study the atmospheric turbulent diffusion and transport of air pollutants, the air tracer technique is an effective means, and several kinds of air tracer material such as sulfur hexafluoride and fluorescent particles have been developed up to now. However, it is difficult to see how much is contributed by the emissions of the respective pollutants to the receptors, and to know the complex transport processes of the tagged air parcels, by simultaneously using these air tracers. Such being the case, a multiple air tracer system has been demanded.
   Therefore, we applied the activable multiple air tracer method (AMAT system) to the investigation of the land and sea breeze. The AMAT system is that the particulate rare-earth elements are released into the atmosphere with pressurized air through the atomizer as air tracers and collected on filter paper; the samples collected are analyzed quantitatively by the neutron activation technique.
   The AMAT system is based on the principle that the field experiment with multiple air tracers can be conducted easily by selecting the elements with the suitable characteristics. As the elements, Eu, Dy, Ho and Lu are appropriate.
   In a comparison experiment between the AMAT and SF₆, we could find that there was no discernible difference in the concentration between the AMAT and SF₆, with small exceptions. Furthermore, we could get a good agreement between the predicted and the observed concentration of the AMAT in the Niihama Experiment.