Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Polycyclic aromatic hydrocarbons in urban atmosphere of Guangzhou, China: Size distribution characteristics and size-resolved gas-particle partitioning
Abstract Size distributions of thirteen polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and organic carbon (OC) in the range of 0.01–18 μm were measured using a nano Micro-Orifice Uniform Deposit Impactor (nano-MOUDI) in an urban location in Guangzhou, China in July 2006. PAH size distributions were fit with five modes and the respective mass median aerodynamic diameters (MMAD) are: Aitken mode (MMAD: ∼0.05 μm), three accumulation modes AMI, AMII, AMIII (MMAD: 0.13–0.17 μm, 0.4–0.45 μm, and 0.9–1.2 μm, respectively), and coarse mode (MMAD: 4–6 μm). Seven-ring PAH was mainly in AMII and AMIII. Five- and six-ring PAHs were found to be abundant in all the three AM. Three- and four-ring PAHs had a significant presence in the coarse mode in addition to the three AM. Size-resolved gas-particle partition coefficients of PAHs (K p) were estimated using measured EC and OC data. The K p values of a given PAH could differ by a factor of up to ∼7 on particles in different size modes, with the highest K p associated with the AMI particles and the lowest K p associated with the coarse mode particles. Comparison of calculated overall K p with measured K p values in Guangzhou by shows that adsorption on EC appeared to be the dominant mechanism driving the gas-particle partitioning of three- and four-ring PAHs while absorption in OM played a dominant role for five- and six-ring PAHs. The calculated equilibrium timescales of repartitioning indicate that five- to seven-ring PAHs could not achieve equilibrium partitioning within their typical residence time in urban atmospheres, while three- and four-ring PAHs could readily reach new equilibrium states in particles of all sizes. A partitioning flux is therefore proposed to replace the equilibrium assumption in modeling PAH transport and fate.
Highlights ► We report the abundances and size distributions of thirteen PAHs in urban aerosols. ► K p is calculated based on EC and OC measurement and compared with measured K p values. ► Partitioning equilibrium timescale is calculated for PAHs with various volatilities.
Polycyclic aromatic hydrocarbons in urban atmosphere of Guangzhou, China: Size distribution characteristics and size-resolved gas-particle partitioning
Abstract Size distributions of thirteen polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and organic carbon (OC) in the range of 0.01–18 μm were measured using a nano Micro-Orifice Uniform Deposit Impactor (nano-MOUDI) in an urban location in Guangzhou, China in July 2006. PAH size distributions were fit with five modes and the respective mass median aerodynamic diameters (MMAD) are: Aitken mode (MMAD: ∼0.05 μm), three accumulation modes AMI, AMII, AMIII (MMAD: 0.13–0.17 μm, 0.4–0.45 μm, and 0.9–1.2 μm, respectively), and coarse mode (MMAD: 4–6 μm). Seven-ring PAH was mainly in AMII and AMIII. Five- and six-ring PAHs were found to be abundant in all the three AM. Three- and four-ring PAHs had a significant presence in the coarse mode in addition to the three AM. Size-resolved gas-particle partition coefficients of PAHs (K p) were estimated using measured EC and OC data. The K p values of a given PAH could differ by a factor of up to ∼7 on particles in different size modes, with the highest K p associated with the AMI particles and the lowest K p associated with the coarse mode particles. Comparison of calculated overall K p with measured K p values in Guangzhou by shows that adsorption on EC appeared to be the dominant mechanism driving the gas-particle partitioning of three- and four-ring PAHs while absorption in OM played a dominant role for five- and six-ring PAHs. The calculated equilibrium timescales of repartitioning indicate that five- to seven-ring PAHs could not achieve equilibrium partitioning within their typical residence time in urban atmospheres, while three- and four-ring PAHs could readily reach new equilibrium states in particles of all sizes. A partitioning flux is therefore proposed to replace the equilibrium assumption in modeling PAH transport and fate.
Highlights ► We report the abundances and size distributions of thirteen PAHs in urban aerosols. ► K p is calculated based on EC and OC measurement and compared with measured K p values. ► Partitioning equilibrium timescale is calculated for PAHs with various volatilities.
Polycyclic aromatic hydrocarbons in urban atmosphere of Guangzhou, China: Size distribution characteristics and size-resolved gas-particle partitioning
Yu, Huan (Autor:in) / Yu, Jian Zhen (Autor:in)
Atmospheric Environment ; 54 ; 194-200
06.02.2012
7 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Size distribution of polycyclic aromatic hydrocarbons in Chinese cities
| Elsevier | 1991
Size Distribution of Polycyclic Aromatic Hydrocarbons in Indoor Airborne Particulates
| Online Contents | 2000