Relationship of polycyclic aromatic hydrocarbons with oxy(quinone) and nitro derivatives during air mass transport

• Published in: The Science of the total environment 2016-12, Vol.572, p.1175-1183
• Main Authors: Harrison, Roy M., Alam, Mohammed S., Dang, Juan, Ismail, I.M., Basahi, J., Alghamdi, Mansour A., Hassan, I.A., Khoder, M.
• Format: Article
• Language: English
• Subjects: air; Air Movements; Air Pollutants - analysis; Atmospheric concentrations; chemical composition; Chemical reactions; coasts; emissions; Environmental Monitoring; hydroxyl radicals; mass transfer; Nitro-PAH; Nitrogen Compounds - analysis; oxidation; photolysis; pollutants; Polycyclic aromatic hydrocarbons; Polycyclic Aromatic Hydrocarbons - analysis; Quinones; Quinones - analysis; Red Sea; Saudi Arabia; Seasons
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.08.030

Airborne concentrations of Polycyclic Aromatic Hydrocarbons (PAH), quinone and nitro derivatives have been measured at three sites on the coast of Saudi Arabia to the north of the city of Jeddah. The PAH show a general reduction in concentrations from northwest to southeast, consistent with a source from a petrochemical works to the northwest of the sampling sites. In comparison, the concentrations of quinones show little variation between the sampling sites consistent with these being predominantly longer lived secondary pollutants formed from PAH oxidation. The nitro-PAH show a gradient in concentrations similar to but smaller than that for the PAH suggesting a balance between atmospheric formation and removal by photolysis. The 2-nitrofluoranthene:1-nitropyrene ratio increases from north to south, consistent with atmospheric chemical formation of the former compound, while the ratio of 2-nitrofluoranthene:2-nitropyrene is consistent with hydroxyl radical as the dominant reactant. An investigation of the changes in PAH congener ratios during air mass transport along the Red Sea coast shows consistency with reaction with a relatively low concentration of hydroxyl radical only for the day with the highest concentrations. It is concluded that while PAH degradation is occurring by chemical reaction, emissions from other locations along the air mass trajectory are most probably also leading to changes in congener ratios. [Display omitted] •PAH, quinones and nitro-PAH are measured at three sites.•PAH show a gradient in concentration from NW to SE.•Inter-site differences of quinones and nitro-PAH are small.•Chemical reactions during advection are considered quantitatively.•Ratios of nitro-PAH are consistent with OH radical attack on PAH.