^(210)Pb,^(228)Th及一些有关同位素在浅海沉积柱样中之分布特征初探

A PRELIMINARY EXPLORATION ON DISTRIBUTIONAL CHARACTERISTICS OF ^(210)pb, ^(228)Th AND SOME RELATED ISOTOPES IN SEDIMENT CORES COLLECTED FROM SHALLOW SEA

本文分析了三个岩芯和一个剖面。结果表明,^(210)Pb比度与有机质含量及粉砂粘土含量呈很好的正相关关系;^(228)Th未过剩;Th放射性强度及^(228)Th/^(232)Th比值皆向深处增大。

Three cores and one shoal section collected from Shapa Port,Yangxi County arc analysed in this paper. The radioactive intensity and ratio of (210)Pb, (228)Ra,(228)Th,(230)Th,(232)Th and the content of organic matter, silty clay, and some minerals in common use from each layer sample have been calculated.The intensity of (210)Pb was clear positive interrelated with the content rf organic matter and silty clay. But it was also clear that it was not interrelated with some minerals which arc in common use.The ratio of (228)Th/(232)Th was less than one. There was no excess of (228)Th. The intensity of Th increased with depth,particularly the intensity of (228)Th and ratio of (228)Th/(232)Th.But the intensity of (228)Ra was negatively interrelated with depth. It is impossible to measure the deposit rate of sediments by (228)Th/(232)Th ratio method in this area.