The Geochemistry Of Radionuclides And Minerals For Sediments In Jiaozhou Bay

The radionuclides, grain-size and minerals composition in a sediment core are determined. The activities of radionuclides of intertidal sediment and surrounding soil near Jiaozhou Bay are measured as well. Atmospheric deposition fluxes of ⁷Be, ²¹⁰Pb and ²¹⁰Po in Xiamen and Qingdao areas are obtained and their characters of deposition and factors that influencing the deposition are discussed. The relationship between the source and radionuclides contents, mineral constitutes of sediment are discussed. The sedimentary rate and flux have been calculated using the distributions of ²¹⁰Pb_ex and ¹³⁷Cs in sediment core.The sedimentary rate of core C23 is 1.67 cm a-1 by two different methods: ²¹⁰Pb_ex and ¹³⁷Cs methods, and the flux is 14.78 kg m^-2 a^-1. The ratios of 40K/226Ra)A.R. in the sediment are consistent with the ratios in Qingdao soils, which concludes the sediment of Jiaozhou Bay mainly come from the surrounding soils. The concentrations of radionuclides in the eastern aeres are higher than those in the western aeres.There are 33 kinds of heavy minerals and 11 kinds of light minerals in the 0.063～0.125 mm graine-size sediment of the core.From factor analysis of the heavy minerals, we can conclude that there are some factors control the minerals profiles, for example, material sources, the distances the sediment moved, the sedimentary conditions and hydrodynamic conditions. From cluster analysis, the core can be divided into three different kinds layers.After analysising the minerals and radionuclides of sediment in Jiaozhou Bay, the conclusion that the sediment come from the land can be obtained.The deposition fluxes of ⁷Be in the atmosphere in Xiamen and Qingdao are lower than other study aeres, while the deposition fluxes of ²¹⁰Pb in the air in Xiamen and Qingdao are higher than the mean flux of the earth. There are good positive correlations between the deposition fluxes of ⁷Be, ²¹⁰Pb or ²¹⁰Po and the amount of precipitation, which suggests that the precipitation dominate ⁷Be, ²¹⁰Pb and ²¹⁰Po deposition fluxes. The deposition fluxes of ⁷Be and ²¹⁰Pb varied with the seasons, lower in winter and higher in other seasons. There are good positive correlations between the deposition fluxes of ⁷Be, ²¹⁰Pb and ²¹⁰Po.The residence time of aerosols of Xiamen evaluated by ²¹⁰Po/²¹⁰Pb fluxes ratio varied between 6.0 to 54.2d with a mean of 27.1d and it varied between 8.3 to 258.5d with a mean of 52.8d in Qingdao.The deposition flux of ²¹⁰Pb in Qingdao between May 2004 and April 2005 is 51% of the...