![]() ![]() Finally, AAs areĪlso transferred by atmospheric deposition to other ecosystems such asĪquatic surfaces, where they act as nutrients since they are particularly bioavailable (Wedyan and Preston, 2008). Their presence in aerosol particlesĬan modify their chemical properties such as acidity/basicity and bufferingĪbility (Cape et al., 2011 Zhang and Anastasio, 2003b). AAs are part of the proteinaceous fractions of aerosol particles that significantly contribute to the organic carbon and organic even showed thatĪAs can react with glyoxal to form secondary aerosol mass (De Zhang and Anastasio, 2003a) the study from De Haan et al. In atmospheric aqueous phases, some AAs have beenįound to potentially influence atmospheric chemistry by reacting withĪtmospheric oxidants (Bianco et al., 2016b McGregor and Anastasio, 2001 Their role in aerosol and cloud formation and hence in the radiative forcing More recently, the role of AAs in new particle formation has also been discussed (Ge et al., 2018). They can modify the ability of the particles to act as cloud condensation nuclei (CCN) (Chan et al., 2005 Kristensson et al., 2010 Li et al.,Ģ013) or ice nuclei (IN) (Pummer et al., 2015 Szyrmer and Zawadzki,ġ997). They have been studied for their hygroscopic properties since Those investigations, their exact role in the atmosphere is still poorly Their sources, their role in the atmospheric chemical and physical processes, and their fate (Cape et al., 2011). Many efforts have been made in the past to assess They have been studied andĬharacterized in atmospheric particles (Barbaro et al., 2020 Matos etĪl., 2016), rainwater (Mace et al., 2003a, b Xu et al., 2019 Yan et al., 2015), fog water (Zhang andĪnastasio, 2003b), and more recently in cloud water (Bianco et al., 2016b Triesch et al., 2021). In the atmosphere, they are commonly detected in the condensed Living organisms are ubiquitous chemical compounds found in variousĮnvironments. This reveals the high complexity of theīio-physico-chemical processes occurring in the multiphase atmosphericįree or combined amino acids (AAs) that make up proteins and cell walls in However, this cannot fully explain the relative contribution Most concentrated AAs encountered in our samples present the longestĪtmospheric lifetimes, and the less dominant ones are clearly efficiently transformed in the atmosphere, potentially explaining their low concentrations. In the cloud medium by biotic or abiotic (mainly oxidation) processes. Finally, the atmospheric aging of AAs has been evaluated byĬalculating atmospheric lifetimes considering their potential transformation The analysis of the AA hygroscopicity also indicates a higher contribution of AAs (80 % on average) that are hydrophilic or neutral, revealing theįact that other AAs (hydrophobic) are less favorably incorporated into cloudĭroplets. AA composition of aquatic organisms (i.e., diatom species) could also explain the high concentrations of Ser in our samples. Relative distribution of AAs in biological matrices (proteins extracted fromīacterial cells or mammalian cells, for example) could explain the dominance Prevailing presence of certain AAs in the cloud samples. We finally assessed the sources and the atmospheric processes that potentially explain the Microphysical properties' fluctuation does not explain the AA variability in our samples, confirming previous studies at the PUY. Layer, especially over the sea surface before reaching the PUY. This work shows thatĪAs are correlated with the time spent by the air masses within the boundary Variability is assessed through a statistical analysis. AA quantification in cloud water is scarce, but the results agree with the few studies that investigated AAs in this aqueous medium. TCAA constitutes between 0.5 and 4.4 % of the dissolved organic carbon measured in the cloud samples. The distribution of AAs among theĬloud events reveals high variability. To 7.7 µM, Ser (serine) being the most abundant AA (23.7 % on average) but with elevated standard deviation, followed by glycine (Gly) Total concentrations of FAAs (TCAAs) vary from 1.2 Spectrometry (LC-MS) and the standard addition method to correct for matrix effects. This quantification has been performed without concentration orĭerivatization, using liquid chromatography hyphened to mass The Puy de Dôme station (PUY – France) during 13 cloud events. Eighteen free amino acids (FAAs) were quantified in cloud water sampled at
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