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Uptake of NO 3 on soot and pyrene surfaces
Author(s) -
Mak Jackson,
Gross Simone,
Bertram Allan K.
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl029756
Subject(s) - soot , pyrene , methane , atmosphere (unit) , hexane , chemistry , environmental chemistry , organic chemistry , combustion , thermodynamics , physics
The reaction of NO 3 with methane soot, hexane soot, and solid pyrene was investigated using a flow tube reactor. The uptake of NO 3 on fresh soot was fast (uptake coefficient >0.1). Based on this result and an assumed density of reactive sites on soot, the time to process or oxidize 90% of a soot surface in the atmosphere would take only approximately five minutes. This suggests that NO 3 chemistry can rapidly oxidize soot surfaces under atmospheric conditions. After exposing soot films to NO 3 for approximately 180 minutes in the laboratory, the uptake reaches a steady‐state value. The steady state uptake coefficients (assuming a geometric surface area) were 0.0054 ± 0.0027 and 0.0025 ± 0.0018 for methane and hexane soot, respectively. These numbers are used to show that heterogeneous reactions between NO 3 and soot are not likely a significant sink of gas‐phase NO 3 under most atmospheric conditions. The uptake of NO 3 on fresh pyrene surfaces was also fast (uptake coefficient >0.1), and much faster than previously suggested. We argue that under certain atmospheric conditions reactions between NO 3 and surface‐bound polycyclic aromatic hydrocarbons (PAHs) may be an important loss process of PAHs in the atmosphere.