AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Chemical Composition of Marine Emissions from Mediterranean Seawaters: Results from a Mesocosm Study
JORGE PEY, H. Langley DeWitt, Brice Temime-Roussel, Aurelie Même, Bruno Charriere, Richard Sempere, Anne Delmont, Sébastien Mas, David Parin, Clemence Rose, Allison Schwier, Badr Rmili, Karine Sellegri, Barbara D'Anna, Nicolas Marchand, Aix-Marseille Université, CNRS, LCE FRE 3416
Abstract Number: 176 Working Group: Aerosol Chemistry
Abstract Marine emissions are among the largest sources of secondary organic aerosols (SOA) globally. Whereas physical processes control the primary production of marine aerosols, biological activity is responsible for most of the organic components released from marine sources and potentially transformed into SOA when exposed to atmospheric oxidants. The Mediterranean atmosphere has been found to have high concentrations of SOA, especially in summer. The origin of these elevated concentrations of SOA is unclear but past measurements suggest that they are mainly from modern (non-fossil) sources.
In view of these recent findings, the gas- and particle-phase chemical fingerprint of marine emissions is desirable. As part of the Source of marine Aerosol particles in the Mediterranean atmosphere (SAM) project, a mesocosm study was conducted at the Oceanographic and Marine Station STARESO (Corsica) in May 2013. During these experiments, 3 mesocosms were deployed. To observe the effect of biological activity on volatile organic compounds (VOCs) and aerosol emissions, two of the mesocosms were enriched with different levels of nitrate and phosphate and one was left unchanged as a control. Physical and chemical properties of mesocosms and their atmospheres were followed during 20 days: aerosol size and concentration were measured by a SMPS; gas-phase composition of VOCs was determined by using PPR-ToF-MS; and aerosol chemical composition was obtained from HR-ToF-AMS. In parallel, incident light, water temperature, pH, conductivity, chemical and biological analyses, fluorescence of chlorophyll-a, and dissolved oxygen concentration were measured in the mesocosms.
Preliminary results suggest new particle formation processes linked to iodine chemistry. Aerosol composition inside the mesocosms was slightly enriched in organic aerosols, being oxygenated organic compounds the most important species in terms of mass concentration, but amine-related aerosol mass peaks varied the greatest in concentration between the mesoscosms. Enhanced VOCs occurred in the enriched mesocosms.