黑碳(BC),作为气溶胶中的关键光吸收成分,对大气辐射平衡产生深远的影响,气候,空气质量和人类健康,等。这也是快速发展的特大城市的长期重点。所以,本研究主要调查重庆市(31,914,300人口)BC的变异特征和潜在原因,这是中国的直辖市之一,作为中国西南地区的重要经济中心。利用MERRA-2再分析数据,我们研究了重庆20年(2002年至2021年)大气BC的长期变化。此外,于2021年3月15日至6月14日在梁平区使用Aethalometer(AE-33)进行BC质量浓度观测,重庆。过去20年的统计分析显示,重庆市的年平均BC浓度为3.42±0.20μg/m3,从2002年到2008年呈增长趋势,随后从2008年到2021年呈下降趋势。月浓度呈“U形”趋势,最低值出现在夏季,最高出现在冬季。由于地形和气象的影响,当地排放主要导致BC污染,其特征是西部高,东部低的空间分布格局。地面观测表明,BC的昼夜变化具有明显的双峰模式,峰值浓度与高交通排放时期一致。BC的变化受气象条件(风,温度,大气边界层)和当地污染源(主要是交通)。此外,极端事件分析表明,局部排放和区域运输(重庆和四川盆地的贡献较高)主要是BC污染的原因。本研究有效地弥补了分析重庆市BC污染分布和来源的不足,为特大城市的大气环境提供有价值的科学见解。
Black carbon (BC), as a critical light-absorbing constituent within aerosols, exerts profound effects on atmospheric radiation balance, climate, air quality and human health, etc. And it is also a long-standing focus in rapidly developing megacities. So, this study primarily focuses on investigating the variation characteristics and underlying causes of BC in
Chongqing (31,914,300 population), which is one of the municipalities directly under the central government of China, serving as a pivotal economic hub in southwest China. Utilizing MERRA-2 reanalysis data, we examined the long-term changes of atmospheric BC over
Chongqing 20 years (from 2002 to 2021). Moreover, BC mass concentration observations were conducted using an Aethalometer (AE-33) from March 15 to June 14, 2021 in Liangping District,
Chongqing. The statistical analysis over the last 20 years reveals an annual mean BC concentration in
Chongqing of 3.42 ± 0.20 μg/m3, exhibiting growth from 2002 to 2008, followed by a decline from 2008 to 2021. Monthly concentration displays a \"U-shaped\" trend, with the lowest values occurring in summer and the highest in winter. Due to topographical and meteorological influences, local emissions primarily contribute to BC pollution, characterized by a spatial distribution pattern of high in the west and low in the east. Ground observation indicates a distinct dual-peaked pattern in the diurnal variation of BC, with peak concentrations aligning with periods of high traffic emissions. The variation in BC is significantly influenced by meteorological conditions (wind, temperature, atmospheric boundary layer) and local pollution sources (predominantly traffic). Furthermore, extreme events analysis suggests that local emissions and regional transport (with higher contributions from
Chongqing and the Sichuan Basin) predominantly contributed to BC pollution. This study effectively makes up for the deficiency in analyzing the distribution and sources of BC pollution in Chongqing, providing valuable scientific insights for the atmospheric environment of megacities.