Precise determination of the cerium isotopic compositions of surface seawater in the Northwest Pacific Ocean and Tokyo Bay
Precise determination of the cerium isotopic compositions of surface seawater in the Northwest Pacific Ocean and Tokyo Bay
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DOI：
10.1016/j.marchem.2006.05.008
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发表时间：
2007-01
期刊：
影响因子：
3
通讯作者：
H. Tazoe;H. Obata;H. Amakawa;Y. Nozaki;T. Gamo
中科院分区：
文献类型：
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作者：
H. Tazoe;H. Obata;H. Amakawa;Y. Nozaki;T. Gamo
成功地测定了海水中的Ce同位素组成（138 Ce/142 Ce），误差为2σm=0.3-0.7 ε单位。在本研究中，1000-3000 L海水样品通过MnO 2纤维浓缩Ce和Nd，以精确测量其同位素比。分析了西北太平洋的四个表层海水样品和东京湾的一个沿海样品。西北太平洋表层海水的Ce同位素比值大多为正ε Ce值（+0.8 ~+1.4）。这些值表明，Ce在地表水来源于大陆地壳优先于幔源物质。我们研究了大陆地壳与洋中脊玄武岩的二元混合模型。然而，该模型不能解释同位素组成和浓度，这意味着大气输入是一个可能的途径Ce进入海洋。在东京湾观测到负εCevalue，表明地幔源。
We succeeded in determining the Ce isotopic composition (138Ce/142Ce) in seawater with an error of 2σm=0.3–0.7 of ε unit. In this study, 1000–3000 L of seawater samples were passed through MnO2fibers to concentrate Ce and Nd for precise measurement of their isotope ratios. Four surface seawater samples of the northwestern Pacific and a coastal sample in Tokyo Bay were analyzed. Most Ce isotope ratios in the surface water showed positive εCevalues (+0.8 to +1.4) in the northwestern Pacific Ocean. These values indicate that Ce in the surface water originates from the continental crust preferentially over mantle-derived materials. We examined binary mixing model between the continental crust and mid-ocean ridge basalt. However the model could not explain both isotopic compositions and concentrations, which implies that the atmospheric input was a possible pathway for Ce into the ocean. A negative εCevalue was observed in Tokyo Bay, suggesting mantle-derived sources.