Characteristics and source apportionment of non-polar organic compounds in PM2.5 from the three megacities in Yangtze River Delta region, China

Abstract

Fine particulate matter samples (PM2.5) were collected from the three megacities of the Yangtze River Delta (i.e., Shanghai, Hangzhou, and Nanjing) during November 11 to December 6, 2016. Organic carbon (OC), elemental carbon (EC), and four types of non-polar organic compounds such as polycyclic aromatic hydrocarbons (PAHs), n-alkanes, hopanes and steranes were analyzed in the samples. The average PM2.5 mass concentrations were 47.0, 64.2 and 45.5 μg m−3 in Shanghai, Hangzhou and Nanjing, respectively. OC and EC concentrations were 4.47 and 0.78 μg m−3, 15.38 and 2.97 μg m−3, 10.35 and 2.06 μg m−3, respectively. n-Alkanes accounted for the largest abundance of the identified non-polar organic compounds, followed by PAHs, hopanes and steranes. The positive matrix factorization (PMF) analysis demonstrated that vehicular emissions, coal burning and industrial emissions were the most important sources. Vehicle exhaust was the major source of emissions in Shanghai (61.0%) and Hangzhou (45.3%), whereas coal combustion emissions was dominant (48.8%) in Nanjing. In addition, the estimated lifetime cancer risk (ILCR) values exposed to PAHs for adults (6.54 × 10−5) and children (7.32 × 10−6) suggested that PAHs levels in this region pose potential health risks. Combining the health risk model with PMF further concluded that vehicular emissions (49.0%) and coal burning (35.7%) were the two major sources that contribute to the ILCR values in these three cities.