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Photoenhanced uptake of NO 2 on mineral dust: Laboratory experiments and model simulations
Author(s) -
Ndour Marieme,
D'Anna Barbara,
George Christian,
Ka Oumar,
Balkanski Yves,
Kleffmann Jörg,
Stemmler Konrad,
Ammann Markus
Publication year - 2008
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 - 10.1029/2007gl032006
Subject(s) - mineral dust , troposphere , photocatalysis , ozone , environmental chemistry , mass fraction , fraction (chemistry) , mineral , mineralogy , atmospheric sciences , chemistry , analytical chemistry (journal) , environmental science , materials science , geology , metallurgy , aerosol , catalysis , chromatography , organic chemistry
Mineral dust contains material such as TiO 2 that is well known to have photocatalytic activity. In this laboratory study, mixed TiO 2 ‐SiO 2 , Saharan dust and Arizona Test Dust were exposed to NO 2 in a coated wall flow tube reactor. While uptake in the dark was negligible, photoenhanced uptake of NO 2 was observed on all samples. For the mixed TiO 2 ‐SiO 2 , the uptake coefficients increased with increasing TiO 2 mass fraction, with BET uptake coefficients ranging from 0.12 to 1.9 × 10 −6 . HONO was observed from all samples, with varying yields, e.g., 80% for Saharan dust. Three‐dimensional modeling indicates that photochemistry of dust may reduce the NO 2 level up to 37% and ozone up to 5% during a dust event in the free troposphere.