Early diagenetic processes in Labrador Sea sediments; uranium-isotope geochemistry
Early diagenetic processes in Labrador Sea sediments; uranium-isotope geochemistry
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DOI：
10.1139/e94-004
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发表时间：
1994
影响因子：
1.4
通讯作者：
C. Garibpy;B. Ghaleb;C. Hillaire‐Marcel
中科院分区：
文献类型：
--
作者：
C. Garibpy;B. Ghaleb;C. Hillaire‐Marcel
The concentration and isotopic composition of U dissolved in pore waters from hemipelagic sediments of the Labrador Sea were determined by thermal ionization mass spectrometry in two 30 cm long box cores. The present fluxes of seawater U that diffuses across the sediment–seawater interface are on the order of 2–4 μg/(cm2∙ka). This diffusion imposes decreasing gradients of dissolved U downwards, but the U concentration in pore waters immediately below the surface is much lower than that of open-ocean seawater. This is a primary feature that cannot be explained by carbonate precipitation due to decompression during core retrieval. More likely, it reflects the presence of a stagnant benthic boundary layer above the sediment–water interface, in which molecular diffusion of U is slower than in the overlying turbulently mixed seawater, and (or) of microzones near the interface where U is bioaccumulated. Uranium is adsorbed at depths onto the solid phase in response to changes in the redox conditions within the ...
