بررسی تغییرات بریلیوم-۷ (Be۷) طبیعی در هوای مجاور سطح زمین در دو ایستگاه اندازه گیری در ایران

Iran Radiological Air Monitoring Center has measured the concentration of atmospheric ۷Be at two stations located in Iran: Tehran (۳۵º ۴۱'), and Zahedan (۲۹º ۲۸') for duration of ۴ 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 ۷Be is the only nuclide found in the air of Iran. ۷Be 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  ۷Be. The ۷Be concentrations are the highest at each of these sites during the warm mid-year months. An important factor in producing the peak concentrations of ۷Be during the warmer month is the increased rates of the vertical transport within the troposphere that occurs during the warm seasons. The concentration of ۷Be in air shows some difference between the obtained data in Tehran and Zahedan stations, with the respective values of ۱۰.۴۱ ± ۱.۵۰E+۰۰ mBqm-۳ in Tehran and ۱۷.۱۰ ± ۱.۹۰E+۰۰ mBqm-۳ in Zahedan. But the seasonal variations of ۷Be concentration behavior is the same. We believe that ۷Be 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.