Source apportionment of PM2.5 in Guangzhou combining observation data analysis and chemical transport model simulation

•The PM2.5 source apportionment result of Guangzhou was provided using a new hybrid method.•The contributions of four major emission sectors to PM2.5 mass in dry and wet seasons were obtained.•Mobile sector was the largest single contributor to PM2.5 in Guangzhou.•The pollutants transported from the areas north of PRD region were important to Guangzhou's air quality in dry season.

A hybrid method combining observation data analysis and chemical transport model simulation was used in this study to provide the PM2.5 source apportionment result of Guangzhou. Four main anthropogenic emission sectors in PRD region were taken into consideration, including mobile, power, industrial and residential. The proportions (Ps) of six major components (sulfate, nitrate, ammonium, SOA, POA and EC) in PM2.5 were acquired by analyzing the daily PM2.5 monitoring data collected in the year of 2013 at an urban sampling site in Guangzhou. WRF/Chem model was used to get the contribution ratios (CRs) of each emission sector to the concentrations of six related primary pollutants, including SO2, NOX, NH3, VOCs, POA and EC. Then the CRs of the four sources to Guangzhou's PM2.5 mass were calculated. It was found that stationary sources (industrial and power) still had the largest contribution (22.2% in dry season, 44.4% in wet season) to PM2.5 in Guangzhou. Mobile sector was the predominant single contributor, with an average contribution of 20.7% in dry season and 37.4% in wet season. Almost all the PM2.5 concentration in Guangzhou was caused by the emissions within PRD region in wet season. In dry season, however, the emissions emitted within PRD region and the pollutants transported from the areas north of PRD region both played important roles.