Seasonal Characteristics of Black Carbon Aerosol and its Potential Source Regions in Baoji, China

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.

One-Year Real-Time Measurement of Black Carbon in the Rural Area of Qingdao, Northeastern China: Seasonal Variations, Meteorological Effects, and the COVID-19 Case Analysis

“…Compared with other rural areas, the average BC concentrations in rural Qingdao were much lower than those in Beijing of China [34] and Delhi of India [27] and slightly higher than those in Mahabaleshwar of India [18] and Byeongcheon of Korea [56]. BC concentrations in both urban areas [18,19,26,36,[57][58][59][60][61][62] and suburban areas [47,55] were higher than those in rural Qingdao areas. The BC concentrations in the remote background areas [24,63,64] were much lower than those in the rural areas of Qingdao.…”

“…CO, a gaseous pollutant from incomplete combustion, showed the same monthly variation as BC, and PM2.5 and BC show the same peak and trough in the monthly pattern, which indicated that BC and combustion-generated atmospheric pollutants have common sources from Qingdao and its surrounding areas. These results indicate that the increase in local and regional anthropogenic primary emissions and adverse meteorological conditions lead to serious pollution of BC in winter [19,36,62], combined with the seasonal distribution pattern meteorological parameters and gas pollution. In each symbol, the whiskers above and below box mark the 90% and 10% percentiles, respectively; the upper and lower edge of the boxes represent the 75% and 25% percentiles, respectively; and the lines and circles inside the boxes denote median and mean values, respectively.…”

“…According to the new BC emissions inventory reported by Peking University, it was pointed out that residential coal combustion was the largest source sector of BC, followed by residential biofuel combustion, coke production, and diesel vehicles [33]. Winter heating in northern China generated large amounts of BC from coal combustion and biomass combustion, especially in rural areas in the north [29,[34][35][36]. Interestingly, various short-term emission reduction measures can effectively reduce BC concentrations and improve air quality, such as the 2008 Beijing Olympics [37] and the 2014 Asia-Pacific Economic Cooperation (APEC) meeting [38].…”

“…The proportion of moderately or severely polluted days (visibility ≥ 5 km; aerosol optical depth (AOD) > 0.5) ranged from 10.77% to 32.79% from 2000 to 2010 [46]. Solid fuel (e.g., biomass fuel combustion) is an important source of BC for winter heating in the north of China [36,47,48]. Although clean heating has only been implemented in the rural areas of Qingdao, most areas have not yet completely adopted clean heating.…”

Equivalent Black Carbon Aerosol Properties and Their Relationship with the Heating Season in Urban Environments

“…The sampling film used in the aethalometer has strong scattering effects, which disturb the absorption calculation, thereby introducing some errors. Therefore, the measurements of the raw aethalometer need to be corrected [19].…”