Evidence for a weakening'dead zone'in Tokyo bay over the past 30years
Evidence for a weakening'dead zone'in Tokyo bay over the past 30years
复制标题
过去30年东京湾“死亡区”减弱的证据
DOI：
10.1007/s10751-011-0463-9
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发表时间：
2012
影响因子：
--
通讯作者：
Y. Kanai and M. Matsuo
中科院分区：
文献类型：
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作者：
K. Shozugawa;N. Hara;Y. Kanai and M. Matsuo
沉积物中无定形赤铁矿(α-Fe_2O_3)的存在证明了过去30多年东京湾疏浚区域的缺氧程度有所减弱。沉积物中铁的化学状态可以作为反映沉积时缺氧程度的指标。2009年，我们从东京湾Makuhari附近的一个疏浚区域采集了岩心沉积物，那里在夏季非常缺氧。对每一层沉积物进行了~(57)Fe-穆斯堡尔能谱分析和超额~(210)Pb测年，在1976-1979年、1986-1989年和2006-2009年的沉积物中发现了无定形赤铁矿。基于沉积环境优化的Eh-pH图的估算，疏浚区域中赤铁矿的存在证明了缺氧/缺氧的规模正在缩小，这些结果与观测到的海水团块的溶解氧水平很好地吻合。
Weakened hypoxia in the past 30 years at a dredged area in Tokyo Bay was proven by the existence of amorphous hematite (α-Fe2O3) in sediments. The chemical states of iron in sediments can become a proxy for the scale of anoxia at the time of sedimentation. In 2009, we collected core sediments from a dredged area off Makuhari in Tokyo Bay that is very strongly anoxic in the summer. Every layer of the sediments was analysed by57Fe Mössbauer spectroscopy and excess 210Pb dating, and amorphous hematite was identified in the sediments from the 1976–1979, 1986–1989 and 2006–2009 layers. Using an estimate based on the Eh-pH diagram optimized for the sedimental environment, the existence of hematite in the dredged area proves that the scale of hypoxia/anoxia is decreasing, and these results agree well with the observed dissolved oxygen level of the seawater mass.