胶州湾铅-210比活度的分布模式及百年尺度的沉积速率

Specific activity distribution patterns of lead-210 and sediment accumu-lation rates in the Jiaozhou Bay in Shandong Province,China

2006年6月在胶州湾采集柱状岩心并对岩心沉积物中铅-210比活度进行测试分析,结果表明,铅-210沿岩心的垂向分布具有两段、三段模式和异常的多段、倒置模式等。基于铅-210的CIC（constant initial concentration）计年模式和铯-137时标,并且结合历史海底地形对比,计算出近百年来胶州湾海域的现代沉积速率为1.49~24.96 mm/a,沉积通量为0.17~2.62 g/（cm2.a）。除沧口水道末端个别区域外,胶州湾多数区域（包含水道）的沉积速率较低,量级为100mm/a,湾内水道主要呈现出微淤甚至侵蚀,表明近百年来胶州湾沉积环境相对稳定,在可作为航道资源的湾内水道并未出现显著淤积。

Column-like cores were collected in the Jiaozhou Bay in June 2006 and the lead-210 specific activity was measured in the sediments of these cores.The results show that there are four types of vertical distribution patterns of lead-210 specific activity,i.e.,the two-section,three-section,multisection and reversed-section patterns.Based on the CIC（constant initial concentration） model,the deposition rates and the depositonal fluxes are estunated as 1.49~24.96 mm/a and 0.17~2.62 g/（cm2 a）,respectively.The magnitude of the accumulation rate is 100 in the study area.A slight sedimentation or even partial erosion occur in the deep channels in the bay.It indicates that the sedimentary environment is relatively stable in the Jiaozhou Bay during the past century.