日本三河湾沉积物岩芯中过剩 210Pb 和 137Cs 的意义。

Implications of excess 210Pb and 137Cs in sediment cores from Mikawa Bay, Japan.

机构信息

Tianjin Academy of Environmental Sciences, Tianjin 300191, China.

出版信息

J Environ Sci (China). 2009;21(5):707-12. doi: 10.1016/s1001-0742(08)62328-1.

PMID:20108676

Abstract

Four sediment cores were collected from Mikawa Bay, Japan, and excess 210Pb and 137Cs were measured by gamma spectrometry. Sedimentation rates for the four cores were determined by 210Pb method. The sedimentation rate range is 0.10-0.70 g/(cm2 x year). The bio-mixing depth for each core is less than 7.0 cm, and was determined by the excess 210Pb profiles as well. Therefore, the bioturbation is slight. The 210Pb-derived dates coincided with the results from 137Cs geochronology. Acceleration in sedimentation rate due to environmental alteration has been found in cores A2.5 and 05AS8, representing two depocenters due to their topography. Evidence of the Tokai Flood in 2000 was found in core 05AS8 according to the profiles of both radioisotopes and trace metals.

摘要

从日本三河湾采集了四个沉积物岩芯，并通过伽马能谱法测量了过剩的 210Pb 和 137Cs。通过 210Pb 法确定了四个岩芯的沉积速率。沉积速率范围为 0.10-0.70 g/(cm2 x year)。每个岩芯的生物混合深度均小于 7.0 cm，也可以通过过剩 210Pb 剖面确定。因此，生物搅动很轻微。210Pb 测年结果与 137Cs 年代学结果一致。由于环境变化导致的沉积速率加速，在 A2.5 和 05AS8 两个岩芯中发现，这两个岩芯由于地形而成为沉积中心。根据放射性同位素和痕量金属的剖面，在 05AS8 岩芯中发现了 2000 年东海洪水的证据。