A new source of ammonia and carboxylic acids in cloud water: The first evidence of photochemical process involving an iron-amino acid complex

Summary

In the present study we investigate the photochemical properties and impact on cloud water of ferric-aspartate complex (Fe(III)−Asp) under irradiation. Fe(III)−Asp complex was investigated as proxy of ferric-amino acids complexes that could be expected to be present in cloud water. First, the fate of complex under monochromatic (313 and 365 nm) and polychromatic (λ ≥ 290 nm) irradiation is investigated and formation quantum yields of Fe2+ are determined. Moreover, hydroxyl radical quantification in the presence of hydrogen peroxide is investigated at cloud water relevant concentrations and under irradiation. Obtained results suggest that hydroxyl radical formation rates are expected to be lower than those obtained considering all iron as aquacomplex or complexed with oxalate. Finally, a phototransformation mechanism for inorganic and organic products formation such as ammonia, malonic, oxalic and formic acids is proposed.