Measurements of Size-resolved Reduced Nitrogen by the Grand Banks: Implications for Marine Particulate Matter during Coastal Fog 2018

Abstract:

Ammonia and alkyl amines have been suggested to play important roles in new particle formation and aerosol growth. The oceans emit nitrogen-containing gases such as ammonia and amines to the atmosphere as a result of cellular rupture during grazing of phytoplankton, allowing them to contribute to the formation of marine aerosols. The study of ammonia and amines is critical to understand the physical, chemical, and biological composition of aerosol in the exchange of gases and particles across the air-sea interface. In this work we improved our analytical technique to quantify and analyze particulate-phase ammonia and amines by ion chromatography coupled with a conductivity detector. To do this, a reliability protocol for calibration standards of alkyl amines has been developed. New stationary phases and suppressors afford high selectivity, separation efficiency, and peak resolution for the ultra-trace nature of the reduced nitrogen species in atmospheric matrices. Size-resolved aerosol samples were collected with a Micro Orifice Uniform Deposit Impactor on a Coastal Fog cruise that travelled along the coast of Eastern Canada in September 2018. We conducted 9 rounds of 24 hour aerosol sampling across various parts of Grand Banks regions, including open ocean (5 samples), the Gulf of the St. Lawrence (2 samples), and in urban harbours (2 samples). Amines were represented ubiquitously in all the samples and the molar ratio of the sum of aminium to ammonium ranged from 0.05 to 0.76 that indicates the importance of amines in particle composition. The results of this analysis will be used to better understand the sources and sinks of reduced nitrogen in the marine atmosphere. Acid-base and organic condensation chemistry will be explored based on the chemical composition of the ambient aerosols. Furthermore, the ocean-atmosphere exchange of amines will be explored based on the physical and biological metrics available from cruise measurements or Earth-observation systems.