Abstract
Abstract. The Chinese Spring Festival is one of the most important traditional festivals in China. The peak transport in the Spring Festival season (spring travel rush) provides a unique opportunity for investigating the impact of human activity on air quality in the Chinese megacities. Emission sources are varied and fluctuate greatly before, during and after the Festival. Increased vehicular emissions during the "spring travel rush" before the 2009 Festival resulted in high level pollutants of NOx (270 μg m−3), CO (2572 μg m−3), black carbon (BC) (8.5 μg m−3) and extremely low single scattering albedo of 0.76 in Shanghai, indicating strong, fresh combustion. Organics contributed most to PM2.5, followed by NO3−, NH4+, and SO42−. During the Chinese Lunar New Year's Eve and Day, widespread usage of fireworks caused heavy pollution of extremely high aerosol concentration, scattering coefficient, SO2, and NOx. Due to the "spring travel rush" after the festival, anthropogenic emissions gradually climbed and mirrored corresponding increases in the aerosol components and gaseous pollutants. Secondary inorganic aerosol (SO42−, NO3−, and NH4+) accounted for a dominant fraction of 74% in PM2.5 due to an increase in human activity. There was a greater demand for energy as vast numbers of people using public transportation or driving their own vehicles returned home after the Festival. Factories and constructions sites were operating again. The potential source contribution function (PSCF) analysis illustrated the possible source areas for air pollutants of Shanghai. The effects of regional and long-range transport were both revealed. Five major sources, i.e. natural sources, vehicular emissions, burning of fireworks, industrial and metallurgical emissions, and coal burning were identified using the principle component analysis. The average visibility during the whole study period was less than 6 km. It had been estimated that 50% of the total light extinction was due to the high water vapor in the atmosphere. This study demonstrates that organic aerosol was the largest contributor to aerosol extinction at 47%, followed by sulfate ammonium, nitrate ammonium, and EC at 22%, 14%, and 12%, respectively. Our results indicated the dominant role of traffic-related aerosol species (i.e. organic aerosol, nitrate and EC) on the formation of air pollution, and suggested the importance of controlling vehicle numbers and emissions in mega-cities of China as its population and economy continue to grow.
Highlights
China is currently playing an important role in the global economic growth and renaissance
PM2.5 accounted for a dominant fraction of 68.5 % in PM10, indicating that fine particle was the main source of aerosol in Shanghai
Three pollution episodes dominated by different emission sources were identified prior to, during, and after the holiday, respectively
Summary
China is currently playing an important role in the global economic growth and renaissance. K. Huang et al.: Impact of anthropogenic emission on air quality over a megacity above the industrial areas with a fast economical growth (van der A et al, 2006). PM10 index was trending down (Chan and Yao, 2008), some aerosol components such as black carbon (BC) and organic carbon increased since 2000 based on an anthropogenic emission inventory of China developed for 1990–2005 (Lei et al, 2011). The heating rate from fossil fuel containing BC is about 100 % larger than biomass burning containing BC, and Asia was subject to large ratio of BC-to-SO2 emissions, an index for the net warming (Ramana et al, 2010). As many developing countries and regions are becoming more industrialized, emissions of air pollutants are likely to increase dramatically. There is a great need to implement control measures to improve air quality and protect public health
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