Search

Assessing the vertical distribution of aerosols in the atmosphere can elucidate the regional sources of accumulated pollutants at different altitudes. Although studies in Hefei have mainly focused on aerosols in the near-surface atmosphere, few studies have assessed the vertical variability in aerosol concentrations. In this study, the vertical aerosol distribution in Hefei was analyzed continuously for one year (from March 2018 to February 2019) using multi-axis differential optical absorption spectroscopy. The aerosol extinction coefficient was the highest in winter (0.94 km−1), followed by autumn (0.63 km−1), spring (0.57 km−1), and summer (0.47 km−1). Local pollution caused the accumulation of aerosols near the surface. The rate of decrease of the aerosol extinction coefficient was higher in autumn and winter than in spring and summer. The diurnal variations of aerosol extinction coefficient in the different seasons were affected by the planetary boundary layer height, and we observed notable high-altitude transport of aerosols in autumn. We assessed the vertical distribution of the aerosol extinction coefficient under different pollution concentrations and identified peak values mainly below a height of 0.5 km. With increasing height, the extinction coefficient decreased linearly and slowly under low PM 2.5 concentrations, whereas decreased more rapidly under high PM 2.5 concentrations. Clustering analysis, the weight potential source concentration function, and the concentration weighted trajectory model inferred different seasonal characteristics in the potential source areas of aerosols at different heights. In addition to local pollution sources, Jiangsu Province was found to be the main source of pollution in Hefei at a height of 0.4 km, whereas Hubei Province was the main source of pollution at a height of 2 km. [Display omitted] • The vertical decline rate of the aerosol extinction coefficient is highest in winter. • The aerosols in autumn exhibit obvious high-altitude area transmission. • Aerosol extinction coefficient decreased rapidly with height under high pollution. • Jiangsu (Hubei) Province was the main source of pollution at 0.4 km (0.2 km) height. [ABSTRACT FROM AUTHOR]

This study investigated the wintertime vertical distributions and source areas of aerosols, NO 2 , and HCHO in a coastal city of Dongying from December 2020 to March 2021, using ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) and a potential source contribution function (PSCF) model, respectively. Moreover, the chemical production sensitivity of O 3 at different height layers was analyzed using HCHO/NO 2 ratios. The results revealed that the wintertime averaged highest concentrations of aerosol (1.25 km−1), NO 2 (14.81 ppb), and HCHO (2.32 ppb) were mainly distributed at the surface layer, 100–200 m layer, and 200–300 m layer, respectively. Regarding the diurnal cycles, high concentrations of aerosol (>1.4 km−1) and NO 2 (>16.0 ppb) usually appeared in the early morning and late afternoon, while high concentrations of HCHO (>2.5 ppb) usually occurred during 12:00–15:00. The PSCF model revealed that the wintertime aerosol mainly originated from Shandong, northern Jiangsu, Korea, and the northwestern Mongolian Plateau. Below 200 m, NO 2 was mainly from western Shandong, whereas above 600 m, it was mainly from northern Shandong and the Beijing-Tianjin-Hebei (BTH) region. The corresponding sources for HCHO were central and southern Shandong (below 200 m) and northern Shandong, northern Jiangsu, and southeastern BTH (above 600 m). In addition, the chemical production sensitivity of O 3 below 100 m was observed only in the VOC-limited regime. The percentages of O 3 production under the NO x -limited, NO x -VOC-limited, and VOC-limited regimes were 10.75% (31.18%), 4.30% (19.35%), and 84.95% (49.47%) at the 500–600 m (900–1000 m) layer. This study has guiding significance for the coordinated control of PM 2.5 and O 3 , and can assist in the implementation of regional joint prevention and control strategies for air pollutants. • The averaged wintertime NO 2 and HCHO profiles all exhibited a Gaussian shape. • The vertical potential sources of aerosol, NO 2 and HCHO were analyzed using PSCF. • O 3 chemical production sensitivity under 100 m was only VOC-limited. • The percentages of VOC-limited O 3 production at 500–600 were 84.95%. [ABSTRACT FROM AUTHOR]