The interest in organic nitrogen and particularly in quantifying and studying the fate of amino acids (AAs) has been growing in the atmospheric-science community. However very little is known about biotic and abiotic transformation mechanisms of amino acids in clouds.In this work, we measured the biotransformation rates of 18 amino acids with four bacterial strains (Pseudomonas graminis PDD-13b-3, Rhodococcus enclensis PDD-23b-28, Sphingomonas sp. PDD-32b-11, and Pseudomonas syringae PDD-32b-74) isolated from cloud water and representative of this environment. At the same time, we also determined the abiotic (chemical, OH radical) transformation rates within the same solutions mimicking the composition of cloud water. We used a new approach by UPLC–HRMS (ultra-performance liquid chromatography–high-resolution mass spectrometry) to quantify free AAs directly in the artificial-cloud-water medium without concentration and derivatization.The experimentally derived transformation rates were used to compare their relative importance under atmospheric conditions with loss rates based on kinetic data of amino acid oxidation in the aqueous phase. This analysis shows that previous estimates overestimated the abiotic degradation rates and thus underestimated the lifetime of amino acids in the atmosphere, as they only considered loss processes but did not take into account the potential transformation of amino acids into each other.

中文翻译：

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云水中氨基酸的生物和非生物转化：实验研究和对大气的影响

在大气科学界，人们对有机氮的兴趣尤其是对量化和研究氨基酸（AAs）的命运的兴趣日益浓厚。然而，人们对云中氨基酸的生物和非生物转化机制知之甚少。在这项工作中，我们测量了四种细菌菌株（假单胞菌PDD-13b-3，红球菌PDD-23b-28）对18种氨基酸的生物转化率。，鞘氨醇单胞 菌sp.PDD-32b-11和丁香假单胞菌PDD-32b-74）与云水中隔离，代表了这种环境。同时，我们还确定了在模拟云水组成的相同溶液中的非生物（化学基团，OH自由基）转化率。我们使用UPLC-HRMS（超高效液相色谱-高分辨率质谱）的新方法直接在人造云-水介质中对游离氨基酸进行了定量，而没有进行浓缩和衍生化。相对重要性在大气条件下的损失率基于水相中氨基酸氧化的动力学数据。该分析表明，先前的估算高估了非生物降解速率，因此低估了大气中氨基酸的寿命，