Amino acids in Antarctica: evolution and fate of marine aerosols

Abstract

Abstract. The chemical composition and size distribution of marine aerosols constitute an important parameter to investigate the latter's impact on global climate change. Amino acids are an important component of organic nitrogen in aerosols and have the ability to activate and act as cloud condensation nuclei, with important effects on the radiation balance. In order to understand which physical and chemical transformations occur during transport processes, aerosol samples were collected during four different Antarctic austral summer campaigns. The mean amino acids concentration detected at the Italian coastal base was 11 pmol m−3. The main components were fine fractions, establishing a local marine source. Once produced on the sea surface, marine aerosols undergo an ageing process, due to various phenomena such as coagulation, or photochemical transformations. This was demonstrated by using the samples collected on the Antarctic plateau, where the background values of amino acids (0.7 and 0.8 pmol m−3) were determined, and concentration enrichment in the coarse particles was observed. Another important source of amino acids in marine aerosols is the presence of biological material, demonstrated through a sampling cruise on the R/V Italica on the Southern Ocean.