Khoshbinfar S, Vahabi Moghaddam M
Department of Physics, University of Guilan, PO Box 3489, Rasht, Iran.
Radiat Prot Dosimetry. 2010 Dec;142(2-4):332-8. doi: 10.1093/rpd/ncq260. Epub 2010 Sep 21.
Natural radionuclides (40)K, (232)Th and (238)U present in soil and anthropogenic (137)Cs a fission product released to the environment mainly through atmospheric testing of nuclear arms and accidents in nuclear installations are the major contributors to terrestrial outdoor exposures. As part of a comprehensive study of environmental radioactivity in the south Caspian region, soil inventories of these radionuclides have been measured in more than 50 locations throughout Guilan, a northern province of Iran with the highest population density. In the case of natural radionuclides, outdoor absorbed dose rates in air have been inferred from concentrations of radionuclides in soil on the basis of which annual effective dose values have been estimated using the method described in UNSCEAR 2000. Calculation of (137)Cs contribution to dose has been performed by considering its soil inventory profiles and associated numerically estimated photon fluxes at 1 m above the ground. Maps representing the contribution of natural and anthropogenic radionuclides to annual effective dose in the study area have been produced using relevant geostatistical technique. Combined annual effective dose equivalent ranges from 33.1 ± 4.9 to 91.9 ± 16.5 μSv · y(-1) with a mean value of 64.7 ± 15.2 μSv · y(-1).
土壤中存在的天然放射性核素（40）K、（232）Th和（238）U以及主要通过核武器大气试验和核设施事故释放到环境中的人为裂变产物（137）Cs是陆地室外照射的主要贡献者。作为里海南部地区环境放射性综合研究的一部分，在伊朗人口密度最高的北部省份吉兰省的50多个地点测量了这些放射性核素的土壤存量。对于天然放射性核素，已根据土壤中放射性核素的浓度推断出空气中的室外吸收剂量率，并在此基础上使用联合国原子辐射效应科学委员会2000年所述方法估算了年有效剂量值。通过考虑（137）Cs的土壤存量分布以及地面上方1米处相关的数值估算光子通量，计算了（137）Cs对剂量的贡献。利用相关地质统计技术绘制了研究区域内天然和人为放射性核素对年有效剂量贡献的地图。年有效剂量当量综合范围为33.1±4.9至91.9±16.5μSv·y-1，平均值为64.7±15.2μSv·y-1。
