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首页> 外文期刊>Environmental Science & Technology >Organic Complexation of Fe(Ⅱ) and Its Impact on the Redox Cycling of Iron in Rain
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Organic Complexation of Fe(Ⅱ) and Its Impact on the Redox Cycling of Iron in Rain

机译：Fe（Ⅱ）的有机配位及其对铁在雨中的氧化还原循环的影响

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摘要

More than 80% of the iron(Ⅱ) present in a dilute (pH 4.5) H_2SO_4 solution was oxidized by hydrogen peroxide (3 μM) in 24 h, whereas in rainwater Fe(Ⅱ) remained stable for days indicating that a complexed form of Fe(Ⅱ) exists in rainwater that protects it against oxidation. When a rain sample was irradiated for 2 h with simulated sunlight, there was a 57 nM increase in Fe(Ⅱ) resulting from photoreduction of organic Fe(Ⅲ) complexes. Once irradiation ceased, the photoproduced Fe(Ⅱ) rapidly oxidized back to its initial concentration of 32 nM prior to irradiation, but not to zero. These photochemical studies demonstrate that during the daytime when sunlight is present there are dynamic interconversions between complexed and uncomplexed Fe-(Ⅱ) and Fe(Ⅲ) species in rainwater. During the night, after the photochemically produced Fe(Ⅱ) is reoxidized to Fe-(Ⅲ), virtually all remaining Fe(Ⅱ) is complexed by ligands which resist further oxidation. Rain samples oxidized under intense UV light lost their ability to stabilize Fe(Ⅱ), suggesting the ligands stabilizing Fe(Ⅱ) are organic compounds destroyed by UV-irradiation. Additional UV-irradiation studies demonstrated that on average 25% of the Fe-complexing ligands in rainwater are extremely strong and cannot be detected by spectrophotometric analysis using ferrozine. The stability of organically complexed Fe-(Ⅱ) has important implications for the bioavailability of rainwater-derived Fe in the surface ocean.
机译：稀（pH 4.5）H_2SO_4溶液中存在的80％以上的铁（Ⅱ）在24小时内被过氧化氢（3μM）氧化，而在雨水中，Fe（Ⅱ）保持稳定数天，这表明铁的络合形式Fe（Ⅱ）存在于雨水中，可以保护其免受氧化。当用模拟的阳光照射雨水样本2 h时，由于有机Fe（Ⅲ）配合物的光还原而使Fe（Ⅱ）增加了57 nM。一旦停止辐照，光生铁（Ⅱ）迅速氧化回到辐照前的初始浓度32 nM，但不降至零。这些光化学研究表明，在白天有阳光的情况下，雨水中复杂的和非复杂的Fe-（Ⅱ）和Fe（Ⅲ）种类之间存在动态的相互转化。在夜间，将光化学生成的Fe（Ⅱ）重新氧化为Fe-（Ⅲ）之后，几乎所有剩余的Fe（Ⅱ）都被能抵抗进一步氧化的配体络合。在强紫外线下氧化的雨水样品失去了稳定Fe（Ⅱ）的能力，表明稳定Fe（Ⅱ）的配体是被紫外线照射破坏的有机化合物。额外的紫外线照射研究表明，雨水中平均有25％的铁络合配体非常强，无法通过使用二茂铁的分光光度分析法检测到。有机络合的Fe-（Ⅱ）的稳定性对雨水来源的Fe在地表海洋中的生物利用度具有重要意义。

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  • 来源
    《Environmental Science & Technology》 |2005年第6期|p.1576-1583|共8页
  • 作者

    R. J. KIEBER; S. A. SKRABAL; B. J. SMITH; J. D. WILLEY;

  • 作者单位

    Department of Chemistry and Biochemistry, University of North Carolina at Wilmington, Wilmington, North Carolina 28403-3297;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境化学;
  • 关键词

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