Characterization, sources, and risk assessment of atmospheric PM10-bound NPAHs and OPAHs in the core area of the Ili River Valley, China

Statistical data indicate that Xinjiang is having the second-highest particulate matter emissions in China over the past two years, yet relevant research data are scarce. PM₁₀ includes a variety of toxic organic substances, including nitro-PAHs (NPAHs) and oxy-PAHs (OPAHs). The objective of this study was to characterize and ascertain the sources of PM₁₀-bound NPAHs and OPAHs in the core area of the Ili River Valley. To analyze 18 NPAHs and 5 OPAHs, gas chromatography-mass spectrometry (GC-MS) was employed, revealing median concentrations of 449.09 pg/m³ for Σ₁₈NPAHs and 9.38 ng/m³ for Σ₅OPAHs. The levels of NPAHs and OPAHs were higher in the heating season (Σ₁₈NPAHs: 641.97 pg/m³; Σ₅OPAHs: 16.41 ng/m³) than in the non-heating season (Σ₁₈NPAHs: 268.68 pg/m³; Σ₅OPAHs: 2.61 ng/m³) in the core area of the Ili River Valley. During the heating season, concentrations were higher in urban areas than in rural areas, with the reverse trend noted in the non-heating season. Source apportionment, conducted through the characteristic ratio method and positive matrix factorization (PMF), identified coal/biomass combustion as the primary source of NPAHs and OPAHs. Moreover, the increase in inhalation and dermal contact lifetime cancer risk (ILCR) values for all sampling sites, seasons, and age categories within the core area of the Ili River Valley ranged from 2.05E-11-5.02E-08, 7.59E-13-1.26E-09, respectively. These values were all below 10^-6, suggesting the absence of carcinogenic risk from exposure to these contaminants.