中文摘要：

对采集珠江三角洲从化、台山等地的11种植物以及对应的土壤样品,采用HPGe-γ能谱分析了其中的天然放射性核素238 U、226 Ra、232 Th和40 K的比活度.结果表明,土壤样品中238 U、226 Ra、232 Th和40 K的平均含量为151.8、146.3、226.6和665.5Bq/kg,高于我国和世界的平均值.植物样品中的238 U含量较低,大多数样品低于检出限,而226 Ra、232 Th和40 K的平均含量相对较高.铁芒萁（Dicranopteris dichotoma）样品中226Ra、232Th含量最高,平均值分别为285.9 Bq/kg、968.5 Bq/kg,对应的生物富集系数（bioconcentration factor）的平均值为2.20、4.23,而其它10种植物226Ra、232Th的生物富集系数均在10-1～10-2的范围.铁芒萁226Ra和232Th的富集系数和转移系数（translocation factor）都大于1,可以认为是226Ra和232Th的超富集植物.

英文摘要：

11 sorts of plant samples and corresponding soil samples were collected in Conghua and Taishan,Pearl River Delta.The specific activity of 238 U、226 Ra、232 Th and 40 K of samples were investigated by using HPGe-γ-ray spectra analysis.The results showed that the average specific activity of 238 U,226 Ra,232 Th and 40 K in soil samples were 151.8,146.3,226.6,665.5 Bq /kg,which were higher than the average values of China and the world.The concentration of 238 U in all sort of plants are very low and most of them are lower than detection limit,while the values of 226 Ra,232 Th and 40 K were high.The contents of 226 Ra and 232 Th in Dicranopteris dichotoma were the highest,whose average specific activity is 285.9,986.2 Bq /kg respectively.The average bioconcentration factors（BFs）of 226Ra,232Th of Dicranopteris dichotoma were 2.20,4.23,respectively,the other 10 sort of plants have BFs of 226Ra,232Th were in the range of 10-1-10-2.The bioconcentration factors and the translocation factors of 226 Ra,232 Th of Dicranopteris dichotoma were all bigger than 1,so Dicranopteris dichotoma can be defined as hyperaccumulator of 226 Ra and 232 Th.