与常规实地测量法不同，论文运用取样分析法研究了成都市不同类型土壤的天然放射性核素含量和比活度，该方法在较大程度上克服了天气、湿度、土壤松结程度等对测量结果的影响。结果表明：（1）与全国和四川省的平均监测值相比，成都市土壤的238 U、40 K的比活度略低，而232 Th和226 Ra比活度则略高，但总体上处于同一水平；（2）取平均值作为典型值，成都市土壤中238 U、226 Ra、232 Th、40 K的含量和比活度分别为2．375×10－6 g· g－1和29．333 Bq· kg－1，2．938×10－12 g· g－1和36．281Bq· kg－1，12．902×10－6 g· g－1和52．384Bq· kg－1，以及1．771×10－2 g· g－1和554．298Bq· kg－1；（3）以不同土壤的天然放射性含量进行比较，238 U含量和226 Ra含量顺序一致，为：黄壤＞灰潮土＞水稻土＞棕壤＞紫色土；232 Th含量顺序是：棕壤＞黄壤＞水稻土＞灰潮土＞紫色土；40 K含量非常相近，可能是人类对土壤的熟化过程使40 K含量趋于平衡。该研究结果可为成都市的天然本底辐射水平调查研究和合理而有效地利用成都市的国土资源提供数据支撑，也可为成都市的建设规划和可持续发展提供必要的参考。%According to Chengdu soil types, this paper analysis the content and its specific activity of the soil samples by the system of low-background gamma spectrometer.This method overcomes various factors that in-fluence on the measurement results, such as the weather, humidity, degree of soil loose knot and so on.(1) With the national's and Sichuan's average values compared, the natural radionuclide specific activity of 238 U, 40 K are slightly lower, and226 Ra, 232 Th are slightly higher, but in the same level generally;(2) the paper takes the mean value of the content of natural radionuclides and the specific activity as the typical value .The content and the specific activity of 238 U are 2.375 ×10 -6 g · g-1 and 29.333 Bq · kg -1 respectively; those of 226 Ra are 2.938 ×10 -12 g· g-1 and 36.281 Bq· kg-1 respectively;those of 232 Th are 12.902· 10 -6 g· g -1 and 52.384 Bq· kg-1 respectively;and those of 40K are 1.771 ×10 -2 g· g-1 and 554.298 Bq· kg -1 respectively.(3) Comparing with the natural radionuclide content of the soils, the content of 238 U and 226 Ra in the same order, as follows:yellow soil>gray damp soil>paddy soil>brown soil>purple soil;the content of 232 Th is in order:brown soil>yellow soil>paddy soil>gray tide soil>purple soil;and the content of 40 K is the same approxi-mately and its possible reasons are that the humans ripening process of the soil tends to balance the natural radi-onuclide content of 40 K.The findings can provide the data support for the investigation and study of the Cheng-du's natural radiation background level and the research of the Chengdu's land resources.It also can provide the essential reference for the Chengdu's construction plan and the sustainable development.
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