title: Role of Organic Coatings in Regulating N2O5 Reactive Uptake to Sea Spray Aerosol.
abstract: Previous laboratory measurements and field observations have suggested that the reactive uptake of N2O5 to sea spray aerosol particles is a complex function of particle chemical composition and phase, where surface active organics can suppress the reactive uptake by up to a factor of 60. To date, there are no direct studies of the reactive uptake of N2O5 to nascent sea spray aerosol that permit assessment of the role that organic molecules present in sea spray aerosol (SSA) may play in suppressing or enhancing N2O5 uptake kinetics. In this study, SSA was generated from ambient seawater and artificial seawater matrices using a Marine Aerosol Reference Tank (MART), capable of producing nascent SSA representative of ambient conditions. The reactive uptake coefficient of N2O5 (γ(N2O5)) on nascent SSA was determined using an entrained aerosol flow reactor coupled to a chemical ionization mass spectrometer for measurement of surface area dependent heterogeneous loss rates. Population averaged measurements of γ(N2O5) for SSA generated from salt water sequentially doped with representative organic molecular mimics, or from ambient seawater, do not deviate statistically from that observed for sodium chloride (γ(N2O5)NaCl = 0.01-0.03) for relative humidity (RH) ranging between 50 and 65%. The results are consistent with measurements made under clean marine conditions at the Scripps Institution of Oceanography Pier and those conducted on nascent SSA generated in the marine aerosol reference tank. The results presented here suggest that organic films present on nascent SSA (at RH greater than 50%) likely do not significantly limit N2O5 reactive uptake.
authors.affiliation: Department of Chemistry and Biochemistry, University of California , San Diego, California 92093, United States.
authors.forename: Olivia S
authors.initials: OS
authors.lastname: Ryder
authors.affiliation: Department of Chemistry and Biochemistry, University of California , San Diego, California 92093, United States.
authors.forename: Nicole R
authors.initials: NR
authors.lastname: Campbell
authors.affiliation: Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
authors.forename: Holly
authors.initials: H
authors.lastname: Morris
authors.affiliation: Department of Civil and Environmental Engineering, University of California , Davis, California 95616, United States.
authors.forename: Sara
authors.initials: S
authors.lastname: Forestieri
authors.affiliation: Department of Chemistry and Biochemistry, University of California , San Diego, California 92093, United States.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ruppel
authors.affiliation: Department of Civil and Environmental Engineering, University of California , Davis, California 95616, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Cappa
authors.affiliation: Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
authors.forename: Alexei
authors.initials: A
authors.lastname: Tivanski
authors.affiliation: Department of Chemistry and Biochemistry, University of California , San Diego, California 92093, United States.|Scripps Institution of Oceanography , San Diego, California 92037, United States.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Prather
authors.affiliation: Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Bertram