Abstract
Abstract. To investigate the impact of marine aerosols on global climate change it is important to study their chemical composition and size distribution. Amino acids are a component of the organic nitrogen in aerosols and particles containing amino acids have been found to be efficient ice nuclei. The main aim of this study was to investigate the L- and D-free amino acid composition as possible tracers of primary biological production in Antarctic aerosols from three different areas: two continental bases, Mario Zucchelli Station (MZS) on the coast of the Ross Sea, Concordia Station at Dome C on the Antarctic Plateau, and the Southern Ocean near the Antarctic continent. Studying the size distribution of amino acids in aerosols allowed us to characterize this component of the water-soluble organic carbon (WSOC) in marine aerosols near their source and after long-range transport. The presence of only free L-amino acids in our samples is indicative of the prevalence of phytoplanktonic material. Sampling at these three points allowed us to study the reactivity of these compounds during long-range transport. The mean total amino acid concentration detected at MZS was 11 pmol m−3, a higher percentage of amino acids were found in the fine fraction. The aerosol samples collected at Dome C had the lowest amino acid values (0.7 and 0.8 pmol m−3), and the coarse particles were found to have higher concentrations of amino acids compared to the coastal site. The amino acid composition in the aerosol collected at Dome C had also changed compared to the coastal site, suggesting that physical and chemical transformations had occurred during long range transport. During the sampling cruise on the R/V Italica on the Southern Ocean, high concentrations of amino acids were found in the total suspended particles, this we attribute to the presence of intact biological material (as microorganisms or plant material) in the sample.
Highlights
The organic composition of marine aerosols is interesting as it contributes a substantial portion of the worldwide aerosol mass, especially in the submicron size fraction (Bigg, 2007)
Several studies (Facchini et al, 2008a, b; Rinaldi et al, 2010) have demonstrated that the organic chemical composition of marine aerosols depends on a combination of different factors, such as primary emission via bubble bursting and the subsequent transformation into secondary aerosol
The mean total concentration of free amino acids determined in this study was very similar to those found in the literature for marine aerosols in remote areas
Summary
The organic composition of marine aerosols is interesting as it contributes a substantial portion of the worldwide aerosol mass, especially in the submicron size fraction (Bigg, 2007). The study of marine aerosols is of interest as anything that can change their size, composition or concentration in the atmosphere may have an impact on the Earth’s climate, since as noted by O’Dowd et al (2004) “Marine aerosol contributes significantly to the global aerosol load and has an important impact on both the Earth’s albedo and climate”. This is because, the sheer extent of the ocean means that marine aerosol is one of the most important natural aerosol sources on a global scale (O’Dowd and De Leeuw, 2007; Rinaldi et al, 2010). Barbaro et al.: Free amino acids in Antarctic aerosol further alter the organic chemical composition and physical proprieties of marine aerosols (Kuznetsova et al, 2005)
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