Global Average Potassium Isotope Composition of Modern Seawater
Global Average Potassium Isotope Composition of Modern Seawater
复制标题
现代海水的全球平均钾同位素组成
DOI：
10.1021/acsearthspacechem.0c00047
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发表时间：
2020
影响因子：
3.4
通讯作者：
Chen, Heng
中科院分区：
文献类型：
--
作者：
Wang, Kun;Close, Hilary G.;Tuller-Ross, Brenna;Chen, Heng
钾同位素体系被认为是研究大陆风化和全球钾循环的一种新示踪剂。在主要储集层中观察到的最大K同位素分馏是在海洋和块状硅酸盐地球(BSE)之间。与疯牛病相比，海水的重同位素含量显著丰富，海水是地球上最重的水库。由于分析有限，目前尚不清楚海水在垂直、横向和全球范围内的K同位素是否均匀。此外，哪些过程(例如，热液输入)以及这些过程在多大程度上促进了海水中的这种重同位素浓缩，仍然没有得到很好的约束。为了更好地了解现代海水的K同位素组成，并研究海底热液喷口对海水K同位素组成的可能影响，我们分析了在大西洋和太平洋两个地点(包括靠近活动的热液喷口区域(灰烬、轴向海山、胡安德富卡海脊))两对深度剖面采集的46个海水样品的K同位素组成。我们发现，在目前的分析不确定性范围内，所有海水样本都具有相同的K同位素组成，无论其位置、深度、[K]浓度和盐度如何。结合我们的新分析和前人的研究数据，我们确定了现代海水最具代表性的K同位素组成为+0.12±0.07‰(2SD)。海水含量(0.5 5±0.18‰)明显高于赤潮，在大陆风化和逆风化过程中需要大量的K同位素分馏。
The potassium isotope system was proposed as a new tracer in continental weathering and global K cycling. The largest K isotope fractionation observed among major reservoirs is between the ocean and bulk silicate Earth (BSE). Seawater is significantly enriched in heavy isotopes compared to BSE, and seawater represents the heaviest reservoir on Earth. Because of limited analyses, it is still unknown whether seawater is homogeneous in terms of K isotopes vertically, laterally, and globally. In addition, what processes (e.g., hydrothermal inputs) and to what degrees these processes have contributed to this heavy isotope enrichment in seawater are still not well constrained. To better understand the K isotopic compositions of modern seawater and to examine the possible influence of seafloor hydrothermal vents on the K isotope composition of seawater, we analyzed the K isotope composition of 46 seawater samples collected as two pairs of depth profiles in two locations from the Atlantic and Pacific oceans, including one near an active hydrothermal vent field (ASHES, Axial Seamount, Juan de Fuca Ridge). We found that within the current analytical uncertainty, all seawater samples have the same K isotope composition regardless of their location, depth, [K] concentration, and salinity. Combining our new analyses with data from previous studies, we define the best representative K isotope composition of modern seawater as +0.12 ± 0.07‰ (2SD). The seawater is significantly higher (0.55 ± 0.18‰) than BSE, which requires large K isotopic fractionation during continental weathering and reverse weathering.
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深海沉积物的化学和矿物学方面
DOI：
--
发表时间：
1961
期刊：
影响因子：
--
作者：
E. Goldberg
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DOI：
--
发表时间：
1970
期刊：
影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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