Fluorescence Quenching of Chlorophyll by Sea Water Components,ACS Earth and Space Chemistry

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Fluorescence Quenching of Chlorophyll by Sea Water Components
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2020-11-19 , DOI: 10.1021/acsearthspacechem.0c00247
Morgan Vallieres ₁ , D. James Donaldson _{1,

2}

Affiliation

Oceanic phytoplankton populations are actively monitored via satellite measurements coupled with local validation. Increasingly, chlorophyll fluorescence is used for such measurements, both from remote platforms and in-situ. A critical aspect of extracting concentrations from steady-state fluorescence intensity measurements is the ability to quantify the extent of fluorescence quenching in the particular environment of interest. Here, we report a quantitative study of the rate constants for chlorophyll fluorescence quenching by common seawater components: halides, sulphate, calcium, magnesium, and ferric ions, as well as the effect of pH on fluorescence intensity. In general, halide anions and Fe(III) are very effective quenchers of chlorophyll fluorescence, with iodide showing a near diffusion-limited rate constant. Although the most concentrated anion in seawater is chloride, the quenching constant obtained from artificial sea water (1.3 × 10⁹ M^–1 s^–1) is higher than that for chloride alone (1.8 × 10⁸ M^–1 s^–1), suggesting that simply considering NaCl is inappropriate to model real seawater. Negligible quenching was observed from Ca²⁺, SO₄^2–, or Mg²⁺, and there was no effect of changing pH between pH = 5 and pH = 10. Quenching by ferric ions has an apparent quenching constant of 8 × 10¹² M^–1 s^–1, which suggests iron–chlorophyll complex formation.

中文翻译：

海水成分对叶绿素的荧光猝灭

通过卫星测量和本地验证积极监测海洋浮游植物种群。叶绿素荧光越来越多地用于从远程平台和现场进行的此类测量。从稳态荧光强度测量中提取浓度的一个关键方面是能够量化特定目标环境中荧光猝灭程度的能力。在这里，我们报告了对常见海水成分：卤化物，硫酸盐，钙，镁和铁离子的叶绿素荧光猝灭速率常数的定量研究，以及pH值对荧光强度的影响。通常，卤化物阴离子和Fe（III）是叶绿素荧光非常有效的猝灭剂，碘化物显示出接近扩散受限的速率常数。⁹ M ^–1 s ^–1）高于单独的氯化物（1.8×10 ⁸ M ^–1 s ^–1），这表明仅考虑NaCl不适用于模拟真实的海水。从Ca 2 ⁺，SO ₄^2–或Mg ²⁺观察到微不足道的淬灭，并且在pH = 5和pH = 10之间改变pH值没有影响。用铁离子淬灭的表观淬灭常数为8×10 ¹² M – ¹ s ^–1，表明铁-叶绿素复合物的形成。

更新日期：2020-12-17

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