个旧地区环境中氡水平及其与地质特点的关系

为了研究个旧地区环境中氡的浓度及分布、运移规律，采用ＳＳＮＴＤ方法，于１９９０－１９９２年间在个旧地区进行了氡的环境地质野外考察和土壤、居室内布点监测，共获４７９个数据。结果表明，尽管在个旧地区未发现铀、钍矿物，土壤氡水平普遍超过世界地壳土壤氡水平均值。居民室内氡水平均值高达４７１．９Ｂｑ·ｍ－３，远高于我国部分省、市近年来所测氡水平值，位于断裂带的居室氡水平高于远离断裂带的居室。个旧地区室内氡夏季高，冬季低，与一些国内、外有关报道结果相反。氡水平与楼层高度呈正相关，顶层为底层的２．７０倍。调查结果可能与个旧地区的环境地质因素有关。建议采取远离地质断裂带建房和防止上升气流逸入室内的防氡辐射进而防癌的措施。

Radon Levels in the Regional Environment of Gejiu, Yunnan, and Their Relationship to the Geological Features

By using a SSNTD method, the study on theconcentrations of radon and its distribution andtransportation patterns in the regional environment of Ge itu was carried out, during the periodof 1990 - 1992, through an environ-geologicalfield survey and the soil and indoor monitoring atselected sites, with 479 data obtained. The results show that, although uranium or thoriumores had not Yet discovered in this area, the soilradon levels were generally higher than the worldaverage of soil radon in the earth'S crust. In theresidential houses located on geological faults,there was an average indoor radon level of up to471. 9 Bq. m-3, much higher than the averageradon level measured in some parts of this countryin recent years. In contrast to the results reportedin domestic and international literatures, the indoor radon levels in this area were higher in summer and lower in winter and were positively correlated to the number of building storeys, withthe indoor radon level at a top storey being asmuch as 2. 70 times that at a ground storey. Thiscould be related to the environmental and geological factors in Gejiu area. It was suggested thatthe measures for preventing radon from causing acancer should be taken, including the construction of residential houses at a distance far awayfrom the geological faults,and the prevention ofascending air streams with radon radiation fromthe escape into the residential rooms.