Zn Isotope Composition in the Water Column of the Northwestern Pacific Ocean: The Importance of External Sources
Zn Isotope Composition in the Water Column of the Northwestern Pacific Ocean: The Importance of External Sources
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DOI：
10.1029/2019gb006379
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发表时间：
2020-01
影响因子：
5.2
通讯作者：
W. Liao;S. Takano;Shun‐Chung Yang;Kuo‐Fang Huang;Y. Sohrin;T. Ho
中科院分区：
文献类型：
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作者：
W. Liao;S. Takano;Shun‐Chung Yang;Kuo‐Fang Huang;Y. Sohrin;T. Ho
我们测定了西北太平洋 (NWPO) 及其边缘海水柱中的锌同位素组成 (δ66Zn)，以研究驱动垂直和空间变化的过程。与之前的研究相比，溶解的δ66Zn在顶部200 m处相对较低，范围为-0.91至+0.24‰，并且随着深度的增加而增加，在深水中达到平均值，+0.38±0.10‰。我们发现NWPO深水区观测到的δ66Zn远低于东北太平洋。箱模型方法表明，深水中的空间变化可能归因于来自沉积物输入或人为气溶胶的同位素轻锌。在地表水中，NWPO 中无论是封闭系统还是开放系统分馏模型得出的分馏因子均小于 1。然而，封闭和开放系统模型与测量数据的拟合度相对较差。因此，我们认为，除了清除、物理混合和生物吸收的影响外，外部输入是导致地表水[Zn]和δ66Zn值变化的主要因素。由于在高气溶胶输入区域观察到地表水中[Zn]升高且δ66Zn相对较轻，气溶胶沉积可能在调节表层海洋中Zn元素和同位素组成方面发挥主导作用。
We determined Zn isotope composition (δ66Zn) in the water column of the Northwestern Pacific Ocean (NWPO) and its marginal seas to investigate the processes driving vertical and spatial variations. Comparable to previous studies, dissolved δ66Zn was relatively low in the top 200 m, ranging from −0.91 to +0.24‰ and increased with depth toward an averaged value, +0.38±0.10‰, in deep water. We found that δ66Zn observed in the deep water of the NWPO was much lower than the Northeastern Pacific Ocean. Box model approaches suggest that spatial variations in the deep water may be attributed to isotopically light Zn originating from sedimentary input or anthropogenic aerosols. In the surface water, the fractionation factors derived from both closed or open system fractionation models are all less than one in the NWPO. However, both closed and open system models show a relatively poor fit to the measured data. We thus propose that external input is a major factor causing the variations of [Zn] and δ66Zn values in surface water, in addition to the effects of scavenging, physical mixing, and biological uptake. As elevated [Zn] and relatively light δ66Zn in the surface water were observed in high aerosol input regions, aerosol deposition may play a dominant role in regulating Zn elemental and isotopic composition in the surface ocean.