title: Formation of nanoparticles of blue haze enhanced by anthropogenic pollution.
abstract: The molecular processes leading to formation of nanoparticles of blue haze over forested areas are highly complex and not fully understood. We show that the interaction between biogenic organic acids and sulfuric acid enhances nucleation and initial growth of those nanoparticles. With one cis-pinonic acid and three to five sulfuric acid molecules in the critical nucleus, the hydrophobic organic acid part enhances the stability and growth on the hydrophilic sulfuric acid counterpart. Dimers or heterodimers of biogenic organic acids alone are unfavorable for new particle formation and growth because of their hydrophobicity. Condensation of low-volatility organic acids is hindered on nano-sized particles, whereas ammonia contributes negligibly to particle growth in the size range of 3-30 nm. The results suggest that initial growth from the critical nucleus to the detectable size of 2-3 nm most likely occurs by condensation of sulfuric acid and water, implying that anthropogenic sulfur emissions (mainly from power plants) strongly influence formation of terrestrial biogenic particles and exert larger direct and indirect climate forcing than previously recognized.
authors.affiliation: Department of Atmospheric Sciences, Texas A&;M University, College Station, TX 77843, USA. zhang@ariel.met.tamu.edu
authors.forename: Renyi
authors.initials: R
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Alexei F
authors.initials: AF
authors.lastname: Khalizov
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.forename: Jun
authors.initials: J
authors.lastname: Zheng
authors.forename: Robert L
authors.initials: RL
authors.lastname: McGraw
authors.forename: Luisa T
authors.initials: LT
authors.lastname: Molina
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000737:chemistry*; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D052638:Particulate Matter / Q000737:chemistry*; D055668:Photochemical Processes; D011210:Power Plants; D013464:Sulfuric Acids / Q000737:chemistry; D014197:Trees / Q000737:chemistry
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter; D013464:Sulfuric Acids; C033158:sulfuric acid