1046 / 2024-09-20 09:24:27

A missing source of secondary organic aerosols in marine atmospheres: influence of phytoplankton emissions and anthropogenic pollutants

marine atmosphere,,organic aerosols,,secondary formation,Biogenic VOCs,isoprene

Marine atmosphere provides favorable conditions for the formation of secondary organic aerosols (SOA), such as acidic seed particles, high humidity and volatile organic compound (VOC) precursors, while the composition or formation of SOA in marine atmospheres is far from clear due to lack of cruise observations. Organosulfates (OSs), generally formed via the interaction between VOCs and acidic sulfate particles, could be potentially important compounds in marine SOA. In this work, shipboard atmospheric observations were conducted over the Asian marginal seas, to investigate the abundance and formation of biogenic isoprene/monoterpene- OSs in marine atmospheres.

The quantified organosulfates accounted for 0.04%– 6.9% of marine organic aerosols. Isoprene-related (nitrooxy-)OSs occupied 27%-87% of the total quantified OSs, following the abundance order of summer>autumn>spring or winter. This order was driven by the marine phytoplankton biomass and sea surface temperature (SST), which controlled the seawater and atmospheric isoprene concentration levels. Under the severe impacts of anthropogenic pollutants from the East Asia continent in winter, monoterpene nitrooxy-OSs, generated with NO_x involved in, elevated to 34.4±35.5 ng/m³ and contributed 68% of the quantified (nitrooxy-)OSs. Our results highlight the notable roles of biogenic OSs and SOA in marine atmospheres over regions with high biological activity and high SST. The formation of biogenic SOA and their roles in altering marine aerosol properties calls for elaboration through cruise observations in different marine environments.