Spatial Distribution of Secondary Organic Aerosol Formation Potential in China Derived from Speciated Anthropogenic Volatile Organic Compound Emissions

Fine
particulate matter (PM2.5), largely composed of
secondary organic aerosol (SOA), is currently one of the most intractable
environmental problems in China. As crucial precursors for SOA, understanding
the formation propensity of various volatile organic compound (VOC)
species and sources is useful for pollution control. In this work,
we estimated the SOA formation potential (SOAP) of anthropogenic VOC
emissions based on an improved speciated VOC emission inventory and
investigated its distribution in China. According to our estimates,
toluene had the largest SOAP, followed by n-dodecane, m-/p-xylene, styrene, n-decane, and n-undecane, while passenger cars, chemical fiber manufacturing,
asphalt paving, and building coating were the top five SOAP-contributing
sources nationwide. The spatial distribution of SOAP in China shows
a distinct pattern of high values in the southeast and low values
in the northwest. Beijing–Tianjin–Hebei and surroundings,
the Yangtze River Delta, Pearl River Delta, and Sichuan–Chongqing
District were found to have the highest SOAP, particularly in urban
areas. The major SOAP-contributing species and sources differed among
these regions, which was attributed to local industrial and energy
structures. Our results suggest that to mitigate PM2.5 pollution
in China, more efficient SOAP-based control measures should be implemented
instead of current emissions-based policies, and VOC control strategies
should be adapted to local conditions.