The hourly concentrations of eight air pollutants relevant for human health and climate (PM_2.5, PM₁₀, O₃, NO, NO₂, NO_x, SO₂, and CO) were investigated for 1 year (January 2018 to December 2018) at an urban location of a megacity in the Middle East (Tehran, Iran). The spatial distributions of air pollutants were detected via inter-site correlations and coefficients of divergence. The most likely predominant atmospheric processes and sources were determined by interpreting the seasonal, weekly, and diel patterns of air pollutants and the lagged correlations among pollutants. The effect of meteorological factors upon the air pollutants was evaluated by investigating the relationships with key weather factors. The locations of the possible local sources were identified by integrating atmospheric circulation and air pollutant data through bivariate polar plots and conditional bivariate probability function. Potential transboundary source areas were detected using potential source contribution function and concentration-weighted trajectory. Results show that emission factors, weather, and photochemical processes mainly shape the diel and weekly cycles of air pollutants. Compared to other pollutants, daily cycles of SO₂ are quite different among sites and show both bimodal and unimodal patterns. While the WPSCF map for O₃ does not show a remarkable pattern, primary gaseous pollutants presented similar distribution patterns with the most potential source areas with high WPSCF values from the western areas. By providing useful information on air pollutants at local and transboundary scales, the current study finally empowers general considerations upon the atmospheric processes and air quality status over the Tehran metropolitan area.

Graphical Abstract

中文翻译：

---

伊朗德黑兰空气污染物可能的排放源和大气光化学过程：微气象因素对空气质量的作用

对与人类健康和气候相关的八种空气污染物（PM _2.5、PM ₁₀、O ₃、NO、NO ₂、NO _x、SO ₂和 CO）的每小时浓度进行了为期一年（2018 年 1 月至 2018 年 12 月）的调查。中东特大城市（伊朗德黑兰）的城市位置。通过站点间相关性和发散系数来检测空气污染物的空间分布。最可能的主要大气过程和来源是通过解释空气污染物的季节、每周和昼夜模式以及污染物之间的滞后相关性来确定的。通过调查与关键天气因素的关系，评价气象因素对空气污染物的影响。通过双变量极坐标图和条件双变量概率函数整合大气环流和空气污染物数据，确定了可能的当地污染源的位置。使用潜在源贡献函数和浓度加权轨迹检测潜在跨境源区。结果表明，排放因子、天气和光化学过程主要影响空气污染物的日循环和周循环。与其他污染物相比，SO ₂的日循环在不同地点之间差异很大，并且表现出双峰和单峰模式。_{虽然O 3}的WPSCF图没有显示出显着的分布规律，但主要气态污染物呈现出相似的分布规律，最有潜力的高WPSCF值的源区来自西部地区。通过提供有关当地和跨界尺度空气污染物的有用信息，当前的研究最终使人们能够对德黑兰大都市区的大气过程和空气质量状况进行一般性考虑。

图形概要