Abstract
Organic aerosols (OAs) account typically for 20–90% of fine particles (PM2.5) in the lower troposphere. They contribute to a wide range of environmental problems, from local issues (e.g., urban haze) to global problems (e.g., climate change). Huge efforts have been dedicated to studying the composition, abundance, spatial and temporal distribution and sources of organic aerosols in China. This review aims to summarize recent studies on characteristics and sources of OAs and assesses the current state of understanding of the organic aerosol pollution in China. The OA constitutes ∼20–45% of the PM2.5 with an annual mean value of 5.2–44.5 μg/m3 at sites across China, which is about five times higher than that reported in North America and Europe. There are thousands of different organic compounds in atmospheric aerosols, but only about 5–10% of them have been identified and quantified. OAs show pronounced spatial variations with much higher concentrations in Northern than Southern China. Seasonally, the highest OA concentrations are observed in the winter, whereas the lowest are in the summer. This is due to higher emission rates from anthropogenic sources (e.g., biomass and coal combustion) and poorer dispersion conditions in the winter. Approximately 60–80% of total OA is apportioned by receptor modeling (such as Chemical Mass Balance, CMB) and tracer-yield method, based on the source profiles of primary organic aerosols (POA) and secondary OA (SOA) derived from local emission sources. A number of OA sources are identified, including motor vehicles, industrial emissions, biomass combustion, food cooking, and coal combustion for POA and anthropogenic and biogenic emissions for SOA. Industrial emissions and motor vehicular exhaust are the dominant sources of organic aerosols in the industrialized areas of Northern China, as well as the Pearl River Delta and Eastern China, whereas in other urban areas, residential coal combustion and motor vehicular exhaust are the dominant sources in winter and summer respectively.
Highlights
Atmospheric aerosols have been well-known as a major air pollutant in China's megacities during the last decades (Chan and Yao, 2008; Yang et al, 2016)
Industrial emissions are major contributors in developed regions, like the Pearl River Delta (PRD) region, Shanghai and Zhejiang. 70% of rural energy derives from combustion of crop residues, and biomass burning has been considered as a dominant source of Organic aerosols (OAs)
Food cooking and coal combustion are reported as significant sources, whose contribution to OA is approximately 20% and 25% respectively
Summary
Atmospheric aerosols have been well-known as a major air pollutant in China's megacities during the last decades (Chan and Yao, 2008; Yang et al, 2016). Organic aerosol (OA) can make up a significant fraction of atmospheric particles, accounting for 20–90% of fine particulate matter (PM2.5) mass in the lower troposphere (Jimenez et al, 2009; Kanakidou et al, 2005; Murphy et al, 2006; Zhang et al, 2007a). A number of field observation and lab studies of organic aerosols have been carried out in China, which have reported that organic matter constitutes a substantial fraction (30–50%) of PM2.5 in Beijing, Shanghai, Guangzhou and Xi'an (He et al, 2011; Huang et al, 2014; Zheng et al, 2005). While organic carbon is always bound to other elements (H, O, N etc) in organic compounds, elemental carbon is that not bound to other elements. Zhang et al (2015b) Wang et al (2016a) Zhao et al (2013) Du et al (2014) Xu et al (2015) Zhang et al (2013a) Sun et al (2014) Ji et al (2016) Wang et al (2015a) Cheng et al (2013b) Guo et al (2012)
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