Abstract
Abstract. Black carbon (BC) forms an important component of particulate matter globally, due to its impact on climate, the environment and human health. Identifying and quantifying its emission sources are critical for effective policymaking and achieving the desired reduction in air pollution. In this study, we present the first direct measurements of urban BC fluxes using eddy covariance. The measurements were made over Beijing within the UK-China Air Pollution and Human Health (APHH) winter 2016 and summer 2017 campaigns. In both seasons, the mean measured BC mass (winter: 5.49 ng m−2 s−1, summer: 6.10 ng m−2 s−1) and number fluxes (winter: 261.25 particles cm−2 s−1, summer: 334.37 particles cm−2 s−1) were similar. Traffic was determined to be the dominant source of the BC fluxes measured during both seasons. The total BC emissions within the 2013 Multi-resolution Emission Inventory for China (MEIC) are on average too high compared to measured fluxes by a factor of 58.8 (winter) and 47.2 (summer). Only a comparison with the MEIC transport sector shows that emissions are also larger (factor of 37.5 in winter and 37.7 in summer) than the measured flux. Emission ratios of BC ∕ NOx and BC ∕ CO are comparable to vehicular emission control standards implemented in January 2017 for gasoline (China 5) and diesel (China V) engines, indicating a reduction of BC emissions within central Beijing, and extending this to a larger area would further reduce total BC concentrations.
Highlights
Particular matter with a diameter ≤ 2.5 μm (PM2.5) is a major contributor to air pollution (Harrison et al, 1997)
Liu et al (2019) performed source apportionment analysis for the same ambient Black carbon (BC) measurements and identified four different BC modes, which were compared with aerosol mass spectrometer (AMS) and SP-AMS measurement to relate each mode to their potential pollutant source
In the case of BC mass fluxes, average values of 5.5 ± 0.49 and 6.1 ± 0.18 ng m−2 s−1 were measured during the winter and summer seasons, respectively
Summary
Particular matter with a diameter ≤ 2.5 μm (PM2.5) is a major contributor to air pollution (Harrison et al, 1997). It is a global concern given its severe impacts on health, as epidemiological studies identify a variety of cardiovascular and respiratory diseases (Lelieveld et al, 2015; Pope and Dockery, 2006). Black carbon (BC), in general, contributes up to 10 %–15 % of overall PM2.5 and is emitted from incomplete combustion of fossil fuel and biofuel (Seinfeld and Pandis, 1998). Reducing BC will potentially have major benefits for both air quality and climate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
