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In situ observation of dust involved photochemistry over southern China

In situ observation of dust involved photochemistry over southern China. Wei Nie 1 , Aijun Ding 1 , Tao Wang 2 , Christian George 3 1 Institute for Climate and Global Change Research/School of Atmospheric Sciences, Nanjing University

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In situ observation of dust involved photochemistry over southern China

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  1. In situ observation of dust involved photochemistry over southern China Wei Nie1, Aijun Ding1, Tao Wang2, Christian George3 1Institute for Climate and Global Change Research/School of Atmospheric Sciences, Nanjing University 2Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China 3CNRS, UMR5256, IRCELYON, Institut de Recherches sur la Catalyse et l’Environnement de Lyon, Villeurbanne, F-69626, France LIFE+ PhotoPaq conference 2014 16 April 2014

  2. Background Global climate change Health effect Dust aerosols IPCC 2007 Atmospheric chemistry Ocean ecosystem LIFE+ PhotoPaq conference 2014 16 April 2014

  3. Roles in photochemistry • Light extinction (scattering and absorbing) • Scavenge reactive gaseous • Scavenge molecular clusters • Direct uptake and decomposition oxidant, e.g. O3 and OH LIFE+ PhotoPaq conference 2014 16 April 2014

  4. Contents • Introduction to the campaign • Roles of dust in new particle formation • Roles of dusts in HONO chemistry • Causes of the observed heterogeneous photochemistry LIFE+ PhotoPaq conference 2014 16 April 2014

  5. Contents • Introduction to the campaign • Roles of dust in new particle formation • Roles of dusts in HONO chemistry • Causes of the observed heterogeneous photochemistry LIFE+ PhotoPaq conference 2014 16 April 2014

  6. Site location Mar to May 2009， 1269m a.s.l. Mt Heng LIFE+ PhotoPaq conference 2014 16 April 2014

  7. Introduction to the campaign Duration：2009. 3. 14 – 6. 1 Measurements： Gaseous: SO2, NOx, NOy, NH3, HNO3, HCl, CO, CO2, VOCs, O3 Aerosols: PM2.5, PM10, BC, Bsp, WSIs, Size distribution, MOUDI, Filter samples Cloud and fog: pH, conductivity, WSIs,organic acids, heavy metals, HCHO, H2O2，S(IV)，PAHs Wet deposition: pH, conductivity, WSIs,organic acids, heavy metals LIFE+ PhotoPaq conference 2014 16 April 2014

  8. Overall results LIFE+ PhotoPaq conference 2014 16 April 2014

  9. Overall results CALIPSO measured vertical profiles of total attenuated backscatter and aerosol subtype on 25 April. MODIS true-color imagery of eastern China on 24 and 25 April 2009. LIFE+ PhotoPaq conference 2014 16 April 2014

  10. Contents • Introduction to the campaign • Roles of dust in new particle formation • Roles of dusts in HONO chemistry • Causes of the observed heterogeneous photochemistry LIFE+ PhotoPaq conference 2014 16 April 2014

  11. New particle formation and growth Weak dust Strong dust NPF can co-exist with dusts, even under very heavy particle loadings! LIFE+ PhotoPaq conference 2014 16 April 2014

  12. New particle formation and growth The formation rates and growth rates were significantly enhanced during dust episodes! LIFE+ PhotoPaq conference 2014 16 April 2014

  13. NPF- possibly additional H2SO4 • Sulfuric acid proxy in DS episodes show different feature; • Sulfate was formed corresponded to NPF in the daytime; • Probably additional H2SO4 was produced related to dust. LIFE+ PhotoPaq conference 2014 16 April 2014

  14. NPF- possibly additional OVOCs • Calculated VOCs was lower in DS episodes; • Potentials of producing low-volatile organic vapors is also lower; • Probably additional low-volatile organic vapors were produced related to dusts

  15. Contents • Introduction to the campaign • Roles of dust in new particle formation • Roles of dusts in HONO chemistry • Causes of the observe heterogeneous photochemistry LIFE+ PhotoPaq conference 2014 16 April 2014

  16. HONO production Nitrite formation was significantly enhanced in the daytime of dust episode! LIFE+ PhotoPaq conference 2014 16 April 2014

  17. Possible related surface processes • Surface photolysis of HNO3(Zhou et al., 2003; Ramazan et al., 2004) • NO2 photo-conversion on the soot surface(Aubinand Abbatt,2007) • Heterogonous photochemical process of NO2 on the surface organic substance(George et al., 2005; Stemmler et al., 2006) • NO2 photo-catalyic on the surface of TiO2(Gustafsson et al.,2006; Ndour et al., 2008) LIFE+ PhotoPaq conference 2014 16 April 2014

  18. HONO formation LIFE+ PhotoPaq conference 2014 16 April 2014

  19. Contents • Introduction to the campaign • Roles of dust in new particle formation • Roles of dusts in HONO chemistry • Causes of the observed heterogeneous photochemistry LIFE+ PhotoPaq conference 2014 16 April 2014

  20. Possible causes-mixture with anthropogenic pollution LIFE+ PhotoPaq conference 2014 16 April 2014

  21. Possible causes-mixture with anthropogenic pollution • Anthropogenic pollutants, e.g. sulfate and BC were enhanced during DS; • Evident secondary coating were formation on the surface of dust particles; • Sufficient solar radiation and RH even during heavy dust storms. LIFE+ PhotoPaq conference 2014 16 April 2014

  22. Summary and implication

  23. Summary and implication • In-situ observed evidence for dust promoted NPF and HONO production; • Suggesting an un-expected roles of Asian dust in the global climate change via influencing the CCN budget; • Indicating that aerosols have potentials to act as oxidant (catalyst) via direct and indirect pathways to enhance the atmospheric oxidation capacity, and thus impact the atmospheric chemistry in a more significant way. LIFE+ PhotoPaq conference 2014 16 April 2014

  24. 谢谢！ Thanks！ LIFE+ PhotoPaq conference 2014 16 April 2014

  25. HONO formation Concentrations of nitrate and BC were higher in photochemical episodes than those in dust storm, excluding the possibility of first two processes. LIFE+ PhotoPaq conference 2014 16 April 2014

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