Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, 63000, Clermont-Ferrand, France.
Université Clermont Auvergne, CNRS, Laboratoire de Météorologie Physique, 63000, Clermont-Ferrand, France.
Chemosphere. 2018 Dec;212:715-722. doi: 10.1016/j.chemosphere.2018.08.128. Epub 2018 Aug 29.
Clouds are complex multiphasic media where efficient chemical reactions take place and where microorganisms have been found to be metabolically active. Hydroxyl radical is the main oxidant in cloud water, and more generally in the atmosphere, during the day and drives the cloud oxidative capacity. However, only one measurement of the steady state hydroxyl radical concentrations in cloud water has been reported so far. Cloud chemistry models are used to estimate the hydroxyl radical concentrations with values ranging from 10 to 10 M that are surely overestimated due to a lack of knowledge about the speciation of the organic matter acting as a sink for hydroxyl radicals. The aim of this work is to quantify the concentration of hydroxyl radicals at steady state in rain and cloud waters and to measure the impact of native microflora on this concentration. First, the non-toxicity of terephthalic acid as probe is controlled before the analysis in real atmospheric water samples. Higher concentrations of hydroxyl radicals are found in cloud waters than in rain waters, with a mean value "1.6 ± 1.5" × 10 M and "7.2 ± 5.0" × 10 M for rain and cloud waters respectively and no real impact of microorganisms was observed. This method allows the measurement of steady state hydroxyl radical levels at very low concentrations (down to 10 M) and it is biocompatible, fast and easy to handle. It is a useful tool, complementary to other methods, to give a better overview of atmospheric water oxidant capacity.
云是复杂的多相介质，其中会发生高效的化学反应，并且已经发现微生物在其中具有代谢活性。羟基自由基是云水中的主要氧化剂，更广泛地说是在大气中，在白天驱动云的氧化能力。然而，到目前为止，只有一项关于云水中稳定态羟基自由基浓度的测量。云化学模型用于估计羟基自由基浓度，范围从 10 到 10 M，由于对作为羟基自由基吸收剂的有机物的形态缺乏了解，这些值肯定被高估了。本工作的目的是定量测量雨水中和云水中稳定态羟基自由基的浓度，并测量本地微生物对该浓度的影响。首先，在分析真实大气水样之前，控制对苯二甲酸作为探针的非毒性。云水中的羟基自由基浓度高于雨水中的，平均值分别为“1.6±1.5”×10 -6 M 和“7.2±5.0”×10 -6 M，并且没有观察到微生物的实际影响。该方法允许在非常低的浓度（低至 10 -6 M）下测量稳定态羟基自由基水平，并且具有生物相容性、快速和易于处理的特点。它是一种有用的工具，与其他方法互补，可以更全面地了解大气水的氧化剂能力。
