Mercury content as a new indicator of ocean stratification and primary productivity in Quaternary sediments off Bahama Bank in the Caribbean Sea
Mercury content as a new indicator of ocean stratification and primary productivity in Quaternary sediments off Bahama Bank in the Caribbean Sea
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DOI：
10.1016/j.yqres.2013.08.006
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发表时间：
2013-11
影响因子：
2.3
通讯作者：
I. Kita;Makoto Kojima;H. Hasegawa;S. Chiyonobu;Tokiyuki Sato
中科院分区：
文献类型：
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作者：
I. Kita;Makoto Kojima;H. Hasegawa;S. Chiyonobu;Tokiyuki Sato
基于加勒比海大巴哈马岸外的ODP1006A孔的岩心样品，我们首次报道了海洋沉积物中汞含量变化与第四纪气候驱动的海洋层结变化有关的证据。350ka和1330ka期间汞含量变化范围为5.9~6 0.7 ng/g，平均值为33.1 ng/g，与δ18浮游值成反比。汞含量的变化与总有机碳含量呈正相关，表明有机质的δ15Norg和δ13Corg值与深水钙质超微浮游动物的绝对丰度有关。海洋汞被认为已经并入了深水浮游植物产生的有机物中。基于这些结果，我们提出了海洋汞在层状低光区形成的温跃层中聚集的机制。海洋沉积物中的汞含量和超微浮游植物组合提供了关于海洋光带分层程度的信息，以及表层和深层浮游植物在产生海洋有机质和改变其δ15Norg和δ13Corg值方面的作用。
We report the first evidence of Hg content in marine sediments changing in connection with the climate-driven changes in ocean stratification during the Quaternary Period based on core samples from ODP Hole 1006A off Great Bahama Bank in the Caribbean Sea. The Hg content ranged from 5.9 to 60.7 ng/g with an average value of 33.1 ng/g during 350 and 1330 ka and changed inversely with δ18Oplanktonic values. The change in Hg content was positively correlated with total organic carbon (TOC) content, indicating connections between the δ15Norg and δ13Corg values of organic matter and the absolute abundance of a deep-dwelling calcareous nannoplankton (Florisphaera profunda). The marine Hg is thought to have been incorporated into the organic matter produced by deep-dwelling phytoplankton. Based on these results, we propose a mechanism by which marine Hg can collect in a thermocline formed in the stratified lower photic zone. Mercury content and nannoplankton assemblage in marine sediment provide information about the extent of stratification of the oceanic photic zone and the role of surface- and deep-dwelling phytoplankton in producing marine organic matter and changing its δ15Norg and δ13Corg values.