عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Iran Radiological Air Monitoring Center has measured the concentration of atmospheric 7Be at two stations located in Iran: Tehran (35º 41'), and Zahedan (29º 28') for duration of 4 years. The gamma emitting nuclides have been collected by high-volume air samplers and measured by gamma spectrometry. The results of the measured gamma emitting nuclides have shown that the cosmogenic 7Be is the only nuclide found in the air of Iran. 7Be is one of radioactive products of the bombardment of atmosphere by the cosmic rays. The data for the two sampling sites show seasonal variations in the concentration of 7Be. The 7Be concentrations are the highest at each of these sites during the warm mid-year months. An important factor in producing the peak concentrations of 7Be during the warmer month is the increased rates of the vertical transport within the troposphere that occurs during the warm seasons. The concentration of 7Be in air shows some difference between the obtained data in Tehran and Zahedan stations, with the respective values of 10.41 ± 1.50E+00 mBqm-3 in Tehran and 17.10 ± 1.90E+00 mBqm-3 in Zahedan. But the seasonal variations of 7Be concentration behavior is the same. We believe that 7Be concentration decreases poleward from the middle latitudes, because of the stability of the tropospheric air is the highest toward the cold polar region and decreases in the rate of vertical mixing within the troposphere.