Radioactivity research in mosses from typical Karst Regions in Leye Tiankeng, Southern China.

Radionuclides in environmental ecosystems have ecotoxicity and health impact on human and environment, so radioactive contamination has always been one of the global concerns. This study mainly focused on the radioactivity of mosses collected from the Leye Tiankeng Group in Guangxi. The activities of Pu measured by SF-ICP-MS and Cs measured by HPGe in moss and soil samples are as follows: 0-2.29 Bq/kg in mosses and 1.5-11.9 Bq/kg in soils for Cs, and 0.025-0.25Bq/kg in mosses and 0.07-0.51Bq/kg in soils for Pu. The range of Pu/Pu atom ratios (0.201 in mosses and 0.184 in soils) and Pu/Cs activity ratios (0.128 in mosses and 0.044 in soils) indicated that the Cs and Pu in study area were mainly contributed by global fallout. Cs and Pu showed similar distribution in soils. However, their behaviors in mosses were quite different due to the differences in the growth environment of mosses. The transfer factors of Cs and Pu from soil to moss varied in different growth stages and specific environments. A weak positive correlation among Cs, Pu in mosses and soil-derived radionuclides suggested that resettlement was predominant here. The negative correlation between Be, Pb and soil-derived radionuclides indicated that Be and Pb came from atmospheric components, while the weak correlation between them suggested that their specific sources were different. The Cu and Ni were moderately enriched in mosses here due to the use of agricultural fertilizers, At the same time, Zn was at a high level in the Lilang area, where transportation was more developed.