黄海和渤海沉积物^(210)Pb活度的分布特征

Distribution of ^(210)Pb activity of sediments in the Yellow and Bohai seas

利用α多道能谱仪测定了黄海和渤海海域58个表层沉积物样品的^(210)Pb活度,探讨了黄海和渤海表层沉积物中210Pb活度的空间分布特征。渤海中部、北黄海中部泥质沉积区和南黄海中部泥质沉积区是^(210)Pb活度的高值区。渤海湾内、莱州湾内及北黄海西南部沿岸海域则是^(210)Pb活度的低值区。黄海和渤海海区^(210)Pb的富集、分布特征受到研究海区水动力条件和沉积物粒级的制约。根据位于黄海和渤海泥质沉积区的3个岩芯210Pb活度的垂直分布资料,并结合2个站位所取岩芯的^(210)Pb活度的垂直分布资料,探讨了^(210)Pb活度的垂直分布与沉积环境之间的关系。黄海和渤海^(210)Pb活度呈现高值的泥质沉积区,其^(210)Pb活度随岩芯深度衰减的垂直分布很有规律且沉积速率较低,由此可以反映泥质沉积区稳定的沉积环境。

210Pb activities were measured in 58 surficial samples collected from the Yellow and Bohai seas with α-multichannel energy dispersive spectrometer, and the spatial distribution of 210Pb activity in the surficial samples were examined. High values are found in the central area of the Bohai Sea, and the central fine-grained sediment areas of the Northern and the Southern Yellow seas. However, 210Pb activities are low in the Bohai and Laizhou bays and off the west coast of the Northern Yellow Sea. The enrichment of 210Pb and the 210Pb spatial distribution are largely controlled by hydrodynamic conditions and the grain size of sediments in the Yellow and Bohai seas. Also the relationship between the vertical distribution of the 210Pb activity and the sedimentary environment was discussed through the analysis of 3 cores in the central areas of the Bohai, the Northern Yellow and the Southern Yellow seas and 2 cores from the references. The vertical distributions of 210Pb activity appear two-segment models regularly in the fine-grained sediment areas of the Yellow and Bohai seas characterized by high 210Pb activities and low sedimentation rates, reflecting that the sedimentary environments in the fine-grained sediment areas are stable.