**Acknowledgement**

This work was supported by the National Natural Science Fundation of China (20937004, 21107060, and 21190054), Toyota Motor Corporation and Toyota Central Research and Development Laboratories Inc.

<sup>\*</sup> Corresponding Author

## **5. References**

360 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

Figure 9, and, therefore force more CCs condense to aerosol phase. Since (NH4)2SO4 and FeSO4 seed aerosols may both influence the semivolatile CCs, there is a competition for CCs to form

**Figure 9.** Hypothesized mechanism for inorganic seed aerosols' effects on SOA formation: ferrous iron Fe (II) reduces or decompose some condensable compounds (CCs), which are oligomer precursors, interrupting oligomerization and generating high volatility products (LCCs or ICs); while acid seed

Effects of various inorganic seeds, including neutral inorganic seed CaSO4, acidic seed (NH4)2SO4, transition metal contained inorganic seeds FeSO4 and Fe2(SO4)3, and a mixture of (NH4)2SO4 and FeSO4, were examined during *m-*xylene or toluene photooxidation. Our results indicate that the presence of CaSO4 seed aerosols and Fe2(SO4)3 seed aerosols have no effect on photooxidation of aromatic hydrocarbons, while the presence of (NH4)2SO4 seed aerosols and FeSO4 seed aerosols have no effect on gas-phase reactions, but can significantly influence SOA generation and SOA yields. (NH4)2SO4 seed aerosols enhance SOA formation and increase SOA yield due to acid catalytic effect of (NH4)2SO4 seeds on particle-phase surface heterogeneous reactions. While FeSO4 seed aerosols suppress SOA formation and decrease SOA yield possibly due to the reduction of some oligomer precursor CCs. These results reveal that many inorganic seeds are not inert during photooxidation process and can significantly influence SOA formation. These observed effects can be incorporated into air quality models to improve their accuracy in predicting SOA and fine particle concentrations.

higher-volatility products (LCCs or ICs) or low-volatility products (e.g. oligomers).

aerosols catalyze aerosol-phase reactions, generating oligomeric products

Biwu Chu, Jingkun Jiang\*, Zifeng Lu, Kun Wang, Junhua Li and Jiming Hao

*State Key Laboratory of Environment Simulation and Pollution Control, School of Environment,* 

This work was supported by the National Natural Science Fundation of China (20937004, 21107060, and 21190054), Toyota Motor Corporation and Toyota Central Research and

**4. Conclusion** 

**Author details** 

*Tsinghua University, Beijing, China* 

Development Laboratories Inc.

**Acknowledgement** 

Corresponding Author

 \*


Lewandowski, M., Jaoui, M., Offenberg, J.H., Kleindienst, T.E., Edney, E.O., Sheesley, R.J., Schauer, J.J., 2008. Primary and secondary contributions to ambient PM in the midwestern United States. Environmental Science & Technology 42, 3303-3309.

**Chapter 13** 

© 2012 Ma licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Ma, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Production of Secondary Organic Aerosol** 

Nonmethane volatile organic compounds (NMOCs) represent a key class of chemical species governing global tropospheric chemistry and the global carbon cycle (Fehsenfeld et al. 1992; Singh and Zimmerman 1992). The most important anthropogenic sources of hydrocarbons include fossil fuel combustion, direct release from industry, industrial processing of chemicals, and waste. The global estimated anthropogenic hydrocarbon flux is 1.0 × 1014 gC per year (Singh and Zimmerman 1992). Biological processes in both marine and terrestrial environments contribute to biogenic hydrocarbon sources. For the terrestrial biosphere, the principal hydrocarbon sources come from vegetation. In regions such as eastern North America, biogenic hydrocarbon emission rate estimates exceed anthropogenic emissions (Guenther et al. 1994). At the global scale it is estimated that vegetation emits 1.2 × 1015 gC per year, an amount equivalent to global methane emissions (Guenther et al. 1995).

Much of the recent work on emissions of biogenic volatile organic compounds (BVOCs) has focused on isoprene. However, in regions dominated by coniferous or non-isoprene emitting deciduous tree species, monoterpenes may dominate BVOC emissions. Monoterpenes comprise a significant portion of BVOC emissions (Guenther et al., 1995; Pio and Valente, 1998), and it is important to understand the atmospheric fates of monoterpenes and their oxidation products. The emission patterns of the various monoterpenes strongly depend on the type of vegetation and on the environmental conditions, however d-limonene makes up the majority of monoterpene emissions over orange groves, while α-pinene and βpinene dominate over most other kinds of forests, especially those composed of oaks and conifers (Pio and Valente, 1998; Christensen et al., 2000). In recent years, the number of relevant studies has increased substantially, necessitating the review of this topic, including emission fluxes of monoterpenes, the effects of species and nutrient limitation on emissions,

secondary organic aerosol yields via condensation and nucleation.

**from Multiphase Monoterpenes** 

Additional information is available at the end of the chapter

Shexia Ma

http://dx.doi.org/10.5772/48135

**1. Introduction** 

