Nitrate (NO₃⁻), which is mainly oxidized from NO₂ by the OH radical (OH·) and O₃ in the atmosphere, is a major component of inorganic aerosols. However, the contributions of the OH· and O₃ pathways to NO₃⁻ in urban aerosols and the influence of air pollution to both pathways remain unclear. Oxygen isotopes of NO₃⁻ were measured for PM_2.5 in Beijing in 2014. The Δ¹⁷O‐NO₃⁻ values (17.0–32.8‰) were significantly higher in winter (27.2 ± 3.6‰) than in summer (24.2 ± 1.3‰). By estimating contributions of O₃ to the NO_x cycle, the Δ¹⁷O values of NO₃⁻ endmembers produced via the NO₂ + OH· (P1), NO₃· + DMS/HC (P2), and N₂O₅ hydrolysis (P3) pathways were calculated for each observation. The contributions of the three pathways (P1: 32 ± 10%, P2: 34 ± 10%, and P3: 34 ± 20% annually) were calculated using the Stable Isotope Analysis in R model. We found that NO₃⁻ formation was dominated by the O₃ oxidation pathways (P2 + P3; 68 ± 23% annually, 73 ± 21% in spring, 59 ± 23% in summer, 75 ± 20% in autumn, and 69 ± 22% in winter). Moreover, PM_2.5, NO₂, and NO₃⁻ pollution decreased the importance of the OH· pathway relative to the O₃ pathways for NO₃⁻ production. However, O₃ pollution increased the importance of the OH· pathway relative to the O₃ pathways for NO₃⁻ production. These results provided a comprehensive analysis on the oxygen isotope records in particulate NO₃⁻ for understanding the relative importance of major oxidation pathways of NO₂. Atmospheric pollution substantially influenced the pathways of NO₂ oxidation to NO₃⁻ in city environments.

15 road and 14 soil dust samples were collected from an oilfield city, Dongying, from 11/2009–4/2010 and analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS) for V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb within PM_2.5, PM₁₀ and PM₁₀₀ fractions synchronously. Metal concentrations, sources and human health risk were studied. Results showed that both soil and road dust exhibited higher values for Mn and Zn and lower values for Co and Cd for the three fractions. Mass concentration ratios of PM_2.5/PM₁₀ and PM₁₀/PM₁₀₀ for metals in road and soil dust indicate that most of the heavy metals tend to concentrate in fine particles. Geoaccumulation index and enrichment factors analysis showed that Cu, Zn and Cd exhibited moderate or heavy contamination and significant enrichment, indicating the influence of anthropogenic sources. Vanadium, Cr, Mn and Co were mostly not enriched and were mainly influenced by crustal sources. For Ni, As and Pb, they ranged from not enriched to moderately enriched and were influenced by both crustal materials and anthropogenic sources. The conclusions were confirmed by multivariate analysis methods. Principle component analysis revealed that the major sources were vehicle emission, industrial activities, coal combustion, agricultural activities and crustal materials. The risk assessment results indicated that metal ingestion appeared to be the main exposure route followed by dermal contact. The most likely cause for cancer and other health risks are both the fine particles of soil and road dusts.