Key Laboratory of Aerosol Chemistry & Physics (KLACP), State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Shanghai Carbon Data Research Center (SCDRC), CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China.
Institute of Geography, University of Bern, Hallerstrasse 12, 3012 Bern, Switzerland; Multiphase Chemistry Department, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany.
Sci Total Environ. 2021 Sep 10;786:147234. doi: 10.1016/j.scitotenv.2021.147234. Epub 2021 May 1.
Polycyclic aromatic compounds (PACs) such as polycyclic aromatic hydrocarbons (PAHs) and their derivatives [oxygenated PAHs (OPAHs), nitrated PAHs (NPAHs), and azaarenes (AZAs)] are toxic and ubiquitous air pollutants. In this study, the concentrations of these PACs were determined in air obtained in spring and autumn of 2012 from urban and rural areas of the Tibetan Plateau, temperate, subtropical, and tropical climate zones in China. Average concentrations (gaseous + particulate) of ∑29PAHs, ∑15OPAHs, ∑11NPAHs, and ∑4AZAs were 928 ± 658, 54 ± 45, 5.3 ± 4.4, 14 ± 11 ng m and 995 ± 635, 67 ± 38, 8.4 ± 6.1, 24 ± 16 ng m in spring and autumn, respectively. Various C fractions and latitude correlated significantly with the concentrations and ratios of PACs. The slopes of the regression of gas-particle partition coefficients (K) of PACs on their sub-cooled liquid vapor pressures (P), indicated both adsorption and absorption to total suspended particles (TSP) for PAHs, OPAHs, and NPAHs in the four studied climatic zones. This result was further supported by comparing the fractions of PACs in TSP calculated from field data with those predicted by the Junge-Pankow adsorption and K absorption models. The concentration ratios of most OPAHs or NPAHs to their parent PAHs and of benzo[e]pyrene/benzo[a]pyrene were higher in autumn than in spring and increased with remoteness from point sources. This suggests enhanced secondary formation of PAH derivatives due to the elevated photochemical activity in autumn and longer ageing of air and associated transformation of PACs during their long-distance transport from source regions (urban sites) to rural sites. Lifetime lung cancer risk estimated from PACs ranged from 0.8 ± 0.6 to 3.1 ± 1.0 (×10), exceeding the value (10) recommended by the WHO. Gaseous PACs contributed substantially to the estimated cancer risks and their contributions increased with decreasing latitude in China.
多环芳烃（PACs）如多环芳烃（PAHs）及其衍生物[含氧多环芳烃（OPAHs）、硝基多环芳烃（NPAHs）和氮杂芳烃（AZAs）]是有毒的、普遍存在的空气污染物。本研究测定了 2012 年春、秋两季中国青藏高原、温带、亚热带和热带气候区城乡空气中这些 PACs 的浓度。∑29PAHs、∑15OPAHs、∑11NPAHs 和∑4AZAs 的总浓度（气态+颗粒态）分别为 928±658、54±45、5.3±4.4、14±11ng/m 和 995±635、67±38、8.4±6.1、24±16ng/m。不同的 C 分数和纬度与 PACs 的浓度和比值显著相关。PACs 的气固分配系数（K）与过冷液体蒸气压（P）的回归斜率表明，在所研究的四个气候区中，PAHs、OPAHs 和 NPAHs 均吸附并吸收到总悬浮颗粒物（TSP）上。这一结果还得到了以下事实的支持：将现场数据中计算得出的 TSP 中 PACs 分数与 Junge-Pankow 吸附和 K 吸收模型预测的分数进行了比较。与春季相比，秋季大多数 OPAHs 或 NPAHs 与其母体 PAHs 的浓度比以及苯并[e]芘/苯并[a]芘的浓度比均升高，并随着与点源的距离增加而升高。这表明由于秋季光化学反应活性增强，以及 PACs 在从源区（城市站点）长距离输送到农村站点的过程中长时间老化和转化，导致 PAH 衍生物的二次生成增强。从 PACs 估算出的终生肺癌风险范围为 0.8±0.6 至 3.1±1.0（×10），超过了世界卫生组织（WHO）推荐的 10。气态 PACs 对估计的癌症风险有很大贡献，其贡献随着中国纬度的降低而增加。
