measurement of 137cs in soils of tehran province

background: an amount of artificial radionuclide has been released into the environment as fallout, resulting from atmospheric nuclear weapon tests, nuclear accidents such as chernobyl and together with air currents have polluted the world. materials and methods: 37 surface soil samples of tehran province were collected in the period between june and september 2008, by implementing methods and standard instruments. the concentration of the artificial radionuclides (137cs) in the soils of tehran province were determined by gamma spectroscopy (hpge), and the data were analyzed both quantitatively and qualitatively. the results have been compared with other radioactivity measurements. results: the concentration of 137cs found in top soils (0-5 cm), in the depth of (12.5-17.5 cm) and in the depth of (27.5- 32.5 cm), ranged from 0.29-28.82 bq.kg-1, 0.3-19.81 bq.kg-1, 0.8-7.43 bq.kg-1, respectively. the total average of 137cs activity, in the above depths was, 11.30, 4.87 and 1.8 bq.kg-1, respectively. conclusion: considering the obtained results from high average values of 137cs in europe and its relation to chernobyl accident, and the higher average concentration of 137cs in tehran province, can also be attributed to chernobyl accident due to the proximity of iran to the place of the accident's occurrence. iran. j. radiat. res., 2009 7 (3): 141-149