Kinetic Studies of Heterogeneous Reactions of Polycyclic Aromatic Hydrocarbon Aerosols with NO₃Radicals

Abstract

Polycyclic aromatic hydrocarbons (PAHs) and their derivates are mutagenic and carcinogenic substances widely distributed in the atmospheric environment. In this study, effective rate constants for heterogeneous reactions of NO 3 radicals with five 4-ring PAHs [benzo [a]anthracene (BaA), chrysene (Ch), pyrene (Py), 1-nitropyrene (1-NP), and 1-hydroxypyrene (1-OHP)] adsorbed on suspended azelaic acid particles are investigated by a mixed-phase relative rate method with gas-phase isoprene as the reference substance. The concentrations of suspended PAH particles and gas-phase isoprene are monitored concurrently by a real-time vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and an online atmospheric gas analysis mass spectrometer, respectively. The obtained effective rate constants for the reactions of BaA, Ch, Py, 1-NP, and 1-OHP particles with NO 3 radicals are 4.3 × 10 −12 , 4.0 × 10 −12 , 6.4 × 10 −12 , 1.3 × 10 −12 , and 1.0 × 10 −11 cm 3 ·molecule −1 ·s −1 , respectively, and their corresponding atmospheric lifetimes range from several minutes to half an hour at the NO 3 radical concentration of 5 × 10 8 molecules·cm −3 . In addition, the NO 3 uptake coefficients on particulate PAHs are estimated according to the consumption of PAHs under the exposure of NO 3 radicals. The experimental results of these heterogeneous reactions in the aerosol state provide supplementary knowledge for kinetic behaviors of airborne PAHs particles.

Heterogeneous Reactions of Pirimiphos-Methyl and Pirimicarb with NO3 Radicals

“…where R p and R c are the respective particle radius and inner core radius (cm), ρ pes the pesticide density (1.2 g cm −3 for PMM and 1.1 g cm −3 for PM), N A the Avogadro's number, η pes the ratio of consumption (∼0.9 and 0.75 for PMM and PM, respectively, in our experiments), M pes the pesticide molecular weight (g mol −1 ), D g diffusion coefficient (∼1 cm 2 s −1 ) for NO 3 radicals, 30 and t the reaction time (s). The uptake coefficients for NO 3 radicals on PMM and PM particles are 0.15 and 0.05, respectively, indicating that 15% and 5% of the NO 3 collisions with PMM and PMM yield reactions.…”

Factors affecting atmospheric 1-, 2-nitropyrenes and 2-nitrofluoranthene in winter at Noto peninsula, a remote background site, Japan

“…The long-range transport of air masses from the Asian Continent to Japan can be explained by the atmospheric pressure pattern of Northeast Asia in cold seasons (Terada et al, 2002). Because NPAHs are highly-reactive (Fan et al, 1996;Feilberg and Nielsen, 2000;Kameda et al, 2011;Liu et al, 2012;Miet et al, 2009a, b and c;Ringuet et al, 2012b;Zhang et al, 2011), and because several of their derivatives, such as hydroxylated NPAHs, are considered toxic (Kameda et al, 2008), monitoring atmospheric NPAHs is important to clarify how they transported from Northeast Asia to other areas. In order to predict movements of atmospheric particulates from Northeast Asia, it is helpful to monitor background sites such as the Noto Peninsula, Japan (Tsapakis and Stephanou, 2007;Yang et al, 2007).…”

Kinetic studies of heterogeneous reactions of particulate phosmet and parathion with NO3 radicals

“…The reactive uptake coefficients (c) of NO 3 radicals on OPPs particles can be expressed as the ratio between the number of OPPs molecules on a single particle consumed in the reaction and the number of NO 3 radicals collision to the particle. With the loss ratios of particulate OPPs and the average concentrations of NO 3 radicals measured in the experiment, the uptake coefficient can be obtained using the following equation (Liu et al, 2012b):…”

“…Here R p is the particle radius (cm), R c the radius of the inner core (cm), q the densities of OPPs (1.5 and 1.3 g cm À3 for phosmet and parathion, respectively), N A the Avogadro's number, g the ratio of consumption (0.91 and 0.93 for phosmet and parathion in the experiment, respectively, which were measured by VUV-ATOFMS), M the molecular weight of OPPs (g mol À1 ), D NO 3 the diffusion coefficient of NO 3 radicals under forced diffusion in the experiment ($1 cm 2 s À1 ) (Liu et al, 2012b), and C NO 3 the average concentration of NO 3 radicals.…”

“…The aerosol generator is an electric tube furnace equipped with two tandem quartz tubes [50 cm (length) Â 3 cm (inner diameter)], each with an independent temperature controller. As a wideexisted organic compound in the atmosphere (Mochida et al, 2007;Wang et al, 2011), azelaic acid was used to produce nuclei due to its little reactivity with NO 3 radicals (Liu et al, 2012b). Azelaic acid was placed in the first tube (433 ± 1 K for phosmet, 428 ± 1 K for parathion), while OPPs sample in the second tube (418 ± 1 K for phosmet, 413 ± 1 K for parathion).…”