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首页> 外文期刊>Marine Chemistry >Measurement of iron chemical speciation in seawater at 4 ℃: The use of competitive ligand exchange-adsorptive cathodic stripping voltammetry
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Measurement of iron chemical speciation in seawater at 4 ℃: The use of competitive ligand exchange-adsorptive cathodic stripping voltammetry

机译：4℃海水中铁化学形态的测定：竞争性配体交换-吸附阴极溶出伏安法的使用

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摘要

Iron is mostly bound to poorly characterised organic ligands; thus, organic ligands are paramount in defining Fe biogeochemical cycling and its control on oceanic primary productivity. Since 1994, Fe chemical speciation has been determined by Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-AdCSV) at room temperature. However, chemical speciation is strongly dependent on temperature and some organic ligands can be temperature sensitive. Here, we compare the use of the CLE-AdCSV at room temperature and at 4 ℃-a temperature closer to that found in the Southern Ocean, one of the largest iron-limited regions. For both temperatures, similar detection limits and total Fe concentrations were found. However, at 4 ℃ the analytical detection window (α_(Fe(TAC)_2) was shifted by 1.4-fold towards the detection of weaker ligands, resulting in up to 2-fold lower ligand concentrations as well as a 2- to 5-fold and 10- to70-fold lower conditional stability constants with inorganic Fe (Fe') and Fe(Ⅲ), respectively. As a result, the Fe' concentration at 4 ℃ was 2-fold greater, resulting in direct implication for Fe bioavailability. Results show that difference in Fe chemical speciation at 4 ℃ was not solely explained by temperature effect on thermodynamics with the exchange ligands or the diffusion of the electroactive complex towards the Hg drop. Lowering analytical window during analysis at room temperature is proposed as a first estimate of temperature effect on iron chemical speciation.
机译：铁主要与特性不佳的有机配体结合；因此，有机配体对于定义Fe生物地球化学循环及其对海洋初级生产力的控制至关重要。自1994年以来，通过竞争性配体交换-吸附阴极溶出伏安法（CLE-AdCSV）在室温下确定了铁的化学形态。但是，化学形态强烈依赖于温度，某些有机配体可能对温度敏感。在这里，我们比较了在室温和4℃下CLE-AdCSV的使用情况，该温度更接近最大的铁限制区域之一的南大洋。对于这两个温度，发现了相似的检出限和总铁浓度。然而，在4℃时，分析检测窗口（α_（Fe（TAC）_2）移向弱配体的检测方向移动了1.4倍，导致配体浓度降低了多达2倍，并降低了2至5无机Fe（Fe'）和Fe（Ⅲ）的条件稳定性常数分别降低了1倍和10至70倍，因此，4℃下的Fe'浓度增加了2倍，直接关系到Fe的生物利用度结果表明，在4℃时Fe化学形态的差异不仅可以通过温度对交换配体对热力学的影响或电活性配合物向Hg的扩散来解释，还建议降低室温下的分析窗口估计温度对铁化学形态的影响。

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  • 来源
    《Marine Chemistry》 |2013年第20期|63-73|共11页
  • 作者

    Christel S. Hassler; Francois-Eric Legiret; Edward C.V. Butler;

  • 作者单位

    University of Technology Sydney, Plant Functional Biology and Climate Change Cluster, PO Box 123, Broadway, NSW 2007, Australia,CSIRO Wealth from Oceans Research Flagship, and CSIRO Marine and Atmospheric Research, Castray Esplanade, Hobart, TAS 7000, Australia;

    Present address: University of Southampton, School of Ocean and Earth Science,National Oceanography Centre Southampton, European Way, SO143ZH Southampton,UK.;

    CSIRO Wealth from Oceans Research Flagship, and CSIRO Marine and Atmospheric Research, Castray Esplanade, Hobart, TAS 7000, Australia,Present address: Australian Institute of Marine Science, Arafura Timor Research Facility, PO Box 41775, Casuarina NT 0811, Australia.;

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  • 正文语种 eng
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  • 关键词

    Fe; chemical speciation; voltammetry; seawater; low temperature; organic ligand; complexation;

    机译：铁化学形态伏安法海水;低温;有机配体复杂化;

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