Role of Organic Coatings in Regulating N2O5 Reactive Uptake to Sea Spray Aerosol

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• 作者：Olivia S. Ryder ; Nicole R. Campbell ; Holly Morris ; Sara Forestieri ; Matthew J. Ruppel ; Christopher Cappa ; Alexei Tivanski ; Kimberly Prather ; Timothy H. Bertram
• 刊名：Journal of Physical Chemistry A
• 出版年：2015
• 出版时间：December 3, 2015
• 年：2015
• 卷：119
• 期：48
• 页码：11683-11692
• 全文大小：546K
• ISSN：1520-5215

文摘

Previous laboratory measurements and field observations have suggested that the reactive uptake of N<sub>2sub>O<sub>5sub> 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 N<sub>2sub>O<sub>5sub> 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 N<sub>2sub>O<sub>5sub> 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 N<sub>2sub>O<sub>5sub> (纬(N<sub>2sub>O<sub>5sub>)) 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 纬(N<sub>2sub>O<sub>5sub>) 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 (纬(N<sub>2sub>O<sub>5sub>)<sub>NaClsub> = 0.01鈥?.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 N<sub>2sub>O<sub>5sub> reactive uptake.