Migration mechanisms of Sr and Cs on terraces.

In order to investigate the impact of environmental conditions on the distribution and migration of Sr in the Longji terrace environment, the activity concentrations of Sr and Cs were determined. The activity concentration ranges of Sr and Cs in surface soil were 0.15-1.04 Bq/kg and 2.16-6.94 Bq/kg, respectively. These results showed that there was a similar trend between the activity concentration of Sr and Cs in the surface soil along the runoff path and their activity concentration were influenced by the slope of the terraced terrain. On the other hand, the activity ranges of Sr and Cs in soil cores were 0.01-2.74 Bq/kg and 0.43-7.19 Bq/kg, respectively. These results indicate that the migration mechanism of Sr is different from that of Cs. As compared with Cs, Sr is significantly influenced by the moisture content. In addition, high span of Cs/Sr activity ratios were found in this study, which were attributed to the characteristics of cultivated land and frequent artificial disturbances that intensified the migration of Sr.