GEOTRACES intercalibration of neodymium isotopes and rare earth element concentrations in seawater and suspended particles. Part 2: Systematic tests and baseline profiles
GEOTRACES intercalibration of neodymium isotopes and rare earth element concentrations in seawater and suspended particles. Part 2: Systematic tests and baseline profiles
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DOI：
10.4319/lom.2012.10.252
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发表时间：
2012-04
期刊：
影响因子：
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通讯作者：
K. Pahnke;T. van de Flierdt;K. Jones;M. Lambelet;S. Hemming;S. Goldstein
中科院分区：
文献类型：
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作者：
K. Pahnke;T. van de Flierdt;K. Jones;M. Lambelet;S. Hemming;S. Goldstein
GEOTRACES计划大规模采集海水样品并分析微量元素和同位素，需要仔细比较和检查不同的样品采集、处理和加工方法。在这里，我们报告了不同过滤器类型、采样瓶和预浓缩方法对海水中ND的检测结果。使用五种不同过滤器类型的未过滤和过滤海水的钕同位素比率和浓度分别在43-56ppm(2σ标准差，SD)和10%(相对2σ标准差)范围内。因此，过滤器的选择对北大西洋西部研究地点的测量参数没有影响。然而，在颗粒物浓度较高的地区，情况可能会有所不同。因此，我们强烈建议对海水进行过滤，以进行Nd同位素和稀土元素浓度的测量。用尼龙涂层不锈钢弹簧尼斯金瓶和微量金属清洁GO-FLO瓶收集的海水溶解的143ND/144ND比率在43ppm(2σSD)内相同。因此，这里使用的尼斯金瓶适合于海水样品的采集，以分析143ND/144ND比值。铁的共沉淀和与HDEHP/H_2MEHP的络合，用C18小柱从海水中预浓缩，在37ppm(2σSD)范围内得到相同的143Nd/144Nd比值。因此，这两种方法都是合适的。报告了北大西洋(BATS)和北太平洋(SAFE)的水柱143ND/144ND比值和ND浓度剖面，以及BATS所有稀土元素的剖面。建议在未来的GEOTRACES巡航中继续对这些基线剖面进行质量控制和相互校准。
The large‐scale collection of seawater samples and analysis of trace elements and isotopes by the GEOTRACES program call for careful comparison and examination of different methods for sample collection, treatment, and processing. Here we report results for different filter types, sampling bottles, and preconcentration methods for Nd from seawater. Neodymium isotope ratios and concentrations of unfiltered and filtered seawater using five different filter types agree within 43‐56 ppm (2σ standard deviation, SD) and 10% (relative 2σ standard deviation), respectively. The filter choice therefore has no effect on the measured parameters at the studied locations in the western North Atlantic. This could well be different, however, in areas of high particle concentrations. We therefore strongly recommend filtration of seawater for Nd isotope and rare earth element concentration measurements. Dissolved 143Nd/144Nd ratios of seawater collected with Niskin bottles with internal nylon‐coated stainless steel springs and trace metal‐clean GO‐FLO bottles were the same within 43 ppm (2σ SD). The Niskin bottles used here are therefore suitable for the collection of seawater samples for the analysis of 143Nd/144Nd ratios. Iron coprecipitation and complexation with HDEHP/H2MEHP using C18 cartridges for the preconcentration of Nd from seawater yielded the same 143Nd/144Nd ratios within 37 ppm (2σ SD). Both methods are therefore appropriate. Water column profiles of 143Nd/144Nd ratios and Nd concentrations are reported for the North Atlantic (BATS) and North Pacific (SAFe), and profiles of all rare earth elements are reported for BATS. These baseline profiles are recommended for continued quality control and intercalibration by future GEOTRACES cruises.