中国季风区土壤^(137)Cs背景值研究

SOIL ^(137)Cs BACKGROUND VALUES IN MONSOON REGION OF CHINA

通过测定山东沂蒙山区、江苏苏南丘陵区以及云南滇池流域背景点样品中土壤137Cs活度,探讨了土壤剖面中137Cs的分布状况,发现不同地区不同质地的土壤137Cs的分布深度有所不同。非耕地137Cs活度呈指数型分布,且与分布深度表现出很强的相关关系;耕地中137Cs活度呈深度分异上的均一性。并确定了这几个地区137Cs的背景值分别为1737.1、1847.2和918.0Bq/m2。地区土壤137Cs背景值的确定使得137Cs示踪技术研究土壤侵蚀退化状况、侵蚀和沉积的空间分布成为可能,为土壤资源的可持续利用、土壤侵蚀的经济损益评估及水土保持措施评价等提供有力的技术支持。

Land degradation,which is resulted from the soil erosion,is one of the major environmental problems.It severely affects the food supplies,environmental safety and the sustainable development in China.Some areas in the monsoon region are suffering from the acute soil erosion.To find out the degree of soil erosion,the proven technique of ^137Cs tracer is definitely one of the best methods,and the key is to ascertain the accuracy of soil ^137Cs background value.The distributions of ^137Cs were explored in soil profiles by detecting the ^137 Cs of soil cores from the Yimeng mountain area in Shandong Province, hills in the southern area of Jiangsu Province and Dianchi catchment in Yunnan Province, respectively. We found that the depth of ^137 Cs distribution is not the same in the soils of various areas. But the ^137 Cs activity shows an exponential distribution in the uncultivated soil and demonstrates a strong correlation with the soil depth, while the 137 Cs activity proves uniform in the soil piowing layer of the cultivated land. The study shows the^ 137 Cs background values of three areas ： 1737.1 Bq/m^2 in Yimeng mountain area, 1847.6 Bq/m^2 in southern area of hills in Jiangsu, 918.0 Bq/m^2 in Dianchi catchment. The certainty of 137Cs background value can technically support the use of^ 137 Cs technique to study the spatial pattern of soil erosion, deposition and the land de benefit and gradation, which provides the support for the sustainable utilization of soil resource, the assessment of economical loss and the evaluation of water and soil conservation measures.