Natural aeolian dust particles have no substantial effect on atmospheric polycyclic aromatic hydrocarbons (PAHs): A laboratory study based on naphthalene

• Published in: Environmental pollution (1987) 2020-08, Vol.263 (Pt A), p.114454-114454, Article 114454
• Main Authors: Zhang, Lulu, Zhang, Xuan, Xing, Wanli, Zhou, Quanyu, Yang, Lu, Nakatsubo, Ryohei, Wei, Yongjie, Bi, Jianrong, Shima, Masayuki, Toriba, Akira, Hayakawa, Kazuichi, Tang, Ning
• Format: Article
• Language: English
• Subjects: Adsorption; Aqueous phase; Asian dust; Heterogeneous interaction; Photodegradation
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2020.114454

Natural aeolian dust (AD) particles are potential carriers of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. The heterogeneous interaction between them may lead to worsened air quality and enhanced cytotoxicity and carcinogenicity of ambient particulates in downwind areas, and this topic requires in-depth exploration. In this study, AD samples were collected from four Asian dust sources, and their physical properties and compositions were determined, showing great regional differences. The physical and chemical interactions of different AD particles with naphthalene (Nap; model PAH) were observed in aqueous systems. The results showed that AD particles from the Loess Plateau had weak adsorption to Nap, which was fitted by the Langmuir isotherm. There was no obvious adsorption to Nap found for the other three AD samples. This difference seemed to depend mainly on the specific surface area and/or the total pore volume. In addition, the Nap in the aqueous solution did not undergo chemical reactions under dark conditions and longwave ultraviolet (UV) radiation but degraded under shortwave UV radiation, and 2-formylcinnamaldehyde and 1,4-naphthoquinone were the first-generated products. The degradation of Nap in the aqueous solution was probably initiated by photoionization, and the reaction rate constant (between 1.44 × 10−4 min−1 and 8.55 × 10−4 min−1) was much lower than that of Nap with hydroxyl radicals. Instead of inducing or promoting the chemical change in Nap, the AD particles slowed photodegradation due to the extinction of radiation. Therefore, it is inferred that natural AD particles have no substantial effect on the transportation and transformation of PAHs in the atmosphere. [Display omitted] •The hygroscopicity of AD particle and its collision with Nap were considered.•Even the AD particle with the largest SSA have only weak adsorption on Nap.•Natural AD particles do not promote the photodegradation of Nap but inhibit it.•Direct photolysis by UV radiation is not the main degradation pathway of Nap. Natural aeolian dust has no obvious physical and chemical effects on PAHs in the atmosphere.