Low-molecular-weight hydroxyacids in marine atmospheric aerosol: evidence of a marine microbial origin

• Main Authors: Y. Miyazaki, M. Sawano, K. Kawamura
• Format: Article
• Language: English
• Published: Copernicus Publications 2014-08-01
• Series: Biogeosciences
• Online Access: http://www.biogeosciences.net/11/4407/2014/bg-11-4407-2014.pdf

Lactic acid (LA) and glycolic acid (GA), which are low-molecular-weight hydroxyacids, were identified in the particle and gas phases within the marine atmospheric boundary layer over the western subarctic North Pacific. A major portion of LA (81%) and GA (57%) was present in the particulate phase, which is consistent with the presence of a hydroxyl group in these molecules leading to the low volatility of the compounds. The average concentration (±SD) of LA in more biologically influenced marine aerosols (33 ± 58 ng m⁻³) was substantially higher than that in less biologically influenced aerosols (11 ± 12 ng m⁻³). Over the oceanic region of phytoplankton blooms, the concentration of aerosol LA was comparable to that of oxalic acid, which was the most abundant diacid during the study period. A positive correlation was found between the LA concentrations in more biologically influenced aerosols and chlorophyll <i>a</i> in seawater (<i>r</i>² = 0.56), suggesting an important production of aerosol LA possibly associated with microbial (e.g., lactobacillus) activity in seawater and/or aerosols. Our finding provides a new insight into the poorly quantified microbial sources of marine organic aerosols (OAs) because such low-molecular-weight hydroxyacids are key intermediates for OA formation.