Mineral dust aerosols promote the formation of toxic nitropolycyclic aromatic compounds

Abstract

Atmospheric nitrated polycyclic aromatic hydrocarbons (NPAHs), which have been shown to have adverse health effects such as carcinogenicity, are formed in part through nitration reactions of their parent polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. However, little is known about heterogeneous nitration rates of PAHs by gaseous NO2 on natural mineral substrates, such as desert dust aerosols. Herein by employing kinetic experiments using a flow reactor and surface analysis by Fourier transform infrared spectroscopy with pyridine adsorption, we demonstrate that the reaction is accelerated on acidic surfaces of mineral dust, particularly on those of clay minerals. In support of this finding, we show that levels of ambient particle-associated NPAHs in Beijing, China, significantly increased during heavy dust storms. These results suggest that mineral dust surface reactions are an unrecognized source of toxic organic chemicals in the atmosphere and that they enhance the toxicity of mineral dust aerosols in urban environments.

Aerosol mixing state revealed by transmission electron microscopy pertaining to cloud formation and human airway deposition

“…[8][9][10] These impacts depend on the aerosol physicochemical properties, which require detailed studies (i) to reduce the uncertainty in aerosol-cloud-climate interactions, one of the largest uncertainties in climate projection; 5,11 and (ii) to understand the various aerosol impacts on human health. [12][13][14] Numerous studies of laboratory experiments, field observations, and model simulations have examined aerosols to understand their fundamental properties, atmospheric transformation and impacts on climate and human health.…”

Atmospheric Reactions of PAH Derivatives: Formation and Degradation

“…Organic compounds adsorbed on the surface of mineral dust can have important health implications (Falkovich et al, 2004). Thus, the formation of 1-NP from Py and NO2 on authentic mineral dust was examined (Kameda et al, 2016).…”

“…Table 1. Observed pseudo-first order rate constants for the reaction of Py on the substrates examined in this study with 3 ppmv NO2 (kobs), percentage of degraded Py (DPy), and yields of 1-NP (Y1-NP) (Reproduced from Kameda et al, 2016).…”

“…IR spectra of pyridine adsorbed on the substrates examined in the study (Reproduced fromKameda et al, 2016).…”

“…Proposed mechanisms for the nitration of aromatic compounds (ArH) on the acidic surface of mineral dust (Reproduced fromKameda et al, 2016). (a) Schematic illustration of the heterogeneous nitration.…”