137 Cs reference inventory and its distribution in surface soil along the Fangchenggang coastal zone of Beibu Gulf

Abstract

The background values of137 Cs along the coast of the Beibu Gulf have not been sufficiently presented in China so far. This thesis collected 55 surface samples and 1 profile sample in the Beibu Gulf. The specific activity of137 Cs and organic contents of individual sample were tested and the accumulation amount of137 Cs in the section sample was calculated.The background value of137 Cs in the research area was finally determined. The thesis also analyzed the distribution features of137 Cs in surface soil along the Fangchenggang coastal zone of the Beibu Gulf. The relationship between the specific activity of137 Cs and organic contents in the sample soil was discussed as well. The findings showed that the background value of137 Cs in the soil of the research area was 626 ± 15 Bq/m2, and the atmospheric precipitation of137 Cs accorded with the precipitation condition of137 Cs in the northern hemisphere. By comparing the background values of137 Cs in multiple places within China, it is suggested that the variance among the background values of137 Cs in regions at the same latitude can mainly be attributed to rainfall. Moreover, the spacial distribution variance of latitude zone, climate factors like typhoon and the particularity of geographic position also have great potential to influence the precipitation of137 Cs. The research on the specific activity of the surface samples and the distribution of sampling sites suggested that natural factors and human activities played an important role in the redistribution of137 Cs in soil. The specific activity of137 Cs in different surface samples exhibited the following order from high to low: natural forest land, paddy field, dry land, grassland, and estuary and gulf. A Pearson's correlation analysis was conducted and significant corelation was found between the values of137 Cs content and organic contents in the surface samples and P01 sediment core, with the corelation coefficients being respectively0.414 and 0.732.Discussing the background value of137 Cs in the Fangchenggang coastal zone of the Beibu Gulf and the distribution features of137 Cs in surface soil along the coast can promote further quantitative research on soil erosion and accumulation along the coast of the Beibu Gulf as well as provide scientific evidence for the evaluation of the environmental impact of the Red Sand Plant.