طبيعي در هواي مجاور سطح زمين در دو ايستگاه اندازه گيري در ايران )VBE( V - بررسي تغييرات بريليوم

Long-Term Variation of Atmospheric Beryllium-7 in Iran

Iran Radiological Air Monitoring Center has measured the concentration of atmospheric 713e at two stations located in Iran: Tehran (35° 41ʹ), and Zahedan (29° 28ʹ) 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 7Bc is the only nuclide found in the air of Iran. 7Bc 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 ʹBe. The ʹBe concentrations are the highest at each of these sites during the warn mid-year months. An important factor in producing the peak concentrations of ʹBe during the warmer month is the increased rates of the vertical transport within the troposphere that occurs during the warm seasons. The concentration of "Be 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 ʹ3 in Tehran and 17.10 + 1.90E+00 mBq mBq m-3 in Zahedan. But the seasonal variations of ʹBe concentration behavior is the same. We believe that ʹBe 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.