This study investigates the concentrations and spatial distribution of toxic heavy metals (Cd, Cu, Pb and Zn) through chemical analysis of rainwater samples collected in Tehran, Iran during winter and spring of 2022, characterized by different land use, emission sources, traffic conditions and population density. The average concentrations of the examined heavy metals at the five sampling sites were 52.9, 11.8, 14.6 and 0.93 μg l⁻¹ for Zn, Pb, Cu and Cd, respectively. The concentrations of all heavy metals were significantly higher (p < 0.05) at the sampling points in central and south Tehran compared to sites in the west and north, due to different urban characteristics, higher pollution emission rates from the traffic and domestic sectors, and local wind patterns developed within the city. High traffic load in the central part of Tehran also escalates the heavy metal concentrations in this region. The significant correlations between the examined heavy metals at the five sites indicate common, local anthropogenic sources. The heavy metal concentrations were higher for rain samples collected in spring than in winter, likely associated with dilution processes in winter and the restriction measures due to COVID-19 pandemic. During the lockdown period, a drastic decrease in traffic load was observed in Tehran, confirming that motor vehicles is the main regulatory factor for air pollution and potential toxic elements in the city.

本研究通过对 2022 年冬季和春季在伊朗德黑兰收集的雨水样本进行化学分析，调查了有毒重金属（Cd、Cu、Pb 和 Zn）的浓度和空间分布，这些样本以不同的土地利用、排放源、交通条件为特征。和人口密度。五个采样点检测的重金属平均浓度分别为52.9、11.8、14.6和0.93 μg l ^-1，其中Zn、Pb、Cu和Cd。 由于城市特征不同、交通和生活部门污染排放率较高以及德黑兰中部和南部采样点的所有重金属浓度均显着高于西部和北部采样点（p <0.05）。城市内形成局部风型。德黑兰市中心的高交通负荷也加剧了该地区的重金属浓度。五个地点检测的重金属之间的显着相关性表明存在共同的当地人为来源。春季收集的雨水样本中的重金属浓度高于冬季，这可能与冬季的稀释过程以及因 COVID-19 大流行而采取的限制措施有关。封锁期间，德黑兰的交通负荷急剧下降，证实机动车辆是该市空气污染和潜在有毒元素的主要调节因素。