| Aerosols, as the major air pollutants in China, are particles suspended in the air,which can lead to degraded atmospheric visibility. Atmospheric aerosols directly affect climate by scattering and absorbing solar radiation, and indirectly affect climate by changing the optical properties and lifetime of clouds. In addition, atmospheric aerosols, especially their ultra-fine fraction, harm human health by causing respiratory and cardiovascular diseases. As the main light-absorber in atmospheric aerosols, black carbon(BC) may cause climate warming by absorbing incoming solar radiation and outgoing infra-red radiation. Moreover, with extremely fine size(usually less than 1 um), BC aerosol is more likely to pose health threat to human being than other aerosols. For these reasons, it is of great significance to carry out BC’s observation and emissions control.In order to better understand the contribution of BC to air pollution and climate change, from November 1, 2013 to October 31, 2014, a one-year continuous observation of BC ambient concentration by an Aethalometer was performed in Chinese Research Academy of Environmental Sciences(CRAES). In combination with the data simultaneously obtained by an aerosol Nephelometer and a Thermo Sientific 5030 particle synchronous monitor, the variation trend of BC aerosol concentration and its relationship with the single scattering albedo(SSA) were analyzed. It was found that the diurnal variation of the BC aerosol concentration in Beijing displayed a bimodal feature with the BC mass concentration peaking at 6- 8 and 20- 24. The SSA showed opposite variation to and negative correlation with BC concentration. During the period of heavy pollution in February, 2014, the variation of black carbon aerosol concentration was not so closely correlated with SSA as above mentioned diurnal variation.In addition, for a more comprehensive understanding of black carbon emissions in China, assisted by the environmental protection departments of Baoding city, a 9-member task force was organized by the Atmospheric Environment Institute(AEI) of CRAES to carry out a in-village questionnaire survey on the energy consumption of Hebei Province’s rural areas. Based on the survey results, coal consumption of around 35000-40000 kt was found, which was 7-8 times that in the national statistical yearbook; plus, most of the coal was burned in raw coal style. In view of the uncontrolled emissions from rural coal combustion, the actual BC emissions may be far more than the existing emission inventory data. Thus, control of rural coal use in China promises an important contribution to China’s BC emission reduction.Based on the research results and literature information, suggestions on BC emission reduction were put forward for China. The first is pre-burning control. Since BC is mainly the product of incomplete combustion of carbon-containing fuels, if we use the carbon-free or carbon-low energy to replace the high-carbon energy, BC produced will be diminished a lot. The second is during-burning control. Also because BC is produced during incomplete combustion, if we increase the combustion efficiency, BC production will be naturally reduced. The third points to post-burning control. If we conduct an end-pipe dust-removal, BC will be removed meantime. It must be pointed out that black carbon emission control, in addition to relying on the technical measures herein, is also dependent on the policy support. China is attaching great importance to air pollution prevention and control, and has issued the Action Plan for Prevention and Control of Atmospheric Pollution in September 10, 2013. Policies such as coal control and yellow-tag vehicles’ s phaseout will contribute to China’s BC control. |
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