Abstract
Continuous measurements of black carbon (BC) aerosol were made at a midsized urban site in Baoji, China, in 2015. The daily average mass concentrations varied from 0.6 to 11.5 µg m–3, with an annual mean value of 2.9 ± 1.7 µg m–3. The monthly variation indicated that the largest loading of BC occurred in January and the smallest in June. The mass concentrations exhibited strong seasonality, with the highest occurring in winter and the lowest in summer. The large BC loadings in winter were attributed to the increased use of fuel for domestic heating and to stagnant meteorological conditions, whereas the low levels in summer were related to the increase in precipitation. BC values exhibited similar bimodal diurnal patterns during the four seasons, with peaks occurring in the morning and evening rush hours and an afternoon trough, which was associated with local anthropogenic activities and meteorological conditions. A potential source contribution function model indicated that the effects of regional transport mostly occurred in spring and winter. The most likely regional sources of BC in Baoji were southern Shaanxi province, northwestern Hubei province, and northern Chongqing during spring, whereas the northeastern Sichuan Basin was the most important source region during winter.
Highlights
Atmospheric aerosols are a widespread concern due to their physicochemical role in atmospheric processes, which can cause them to disturb the solar radiative balance of the earth (Bellouin et al, 2005; Gordon et al, 2016)
black carbon (BC) values exhibited similar bimodal diurnal patterns during the four seasons, with peaks occurring in the morning and evening rush hours and an afternoon trough, which was associated with local anthropogenic activities and meteorological conditions
The differences in the BC mass concentrations can be attributed to the distinct emission sources and meteorological conditions as well as the different methods and times of year applied for BC measurement
Summary
Atmospheric aerosols are a widespread concern due to their physicochemical role in atmospheric processes, which can cause them to disturb the solar radiative balance of the earth (Bellouin et al, 2005; Gordon et al, 2016). In 2008, the total BC emission in China was estimated to be 1604.94 Gg, with 695.03 Gg, 636.02 Gg, and 194.63 Gg contributed by industry, the residential sector, and transportation, respectively. These three sources together contributed approximately 95% of the total BC (Zhang et al, 2013a). A number of measurements have been carried out in urban areas of China—for instance, in the Beijing–Tianjin–Hebei region (Chen et al, 2016; Wang et al, 2016a), Yangtze River Delta area
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