Numerical simulations for the sources apportionment and control strategies of PM_2.5 over Pearl River Delta, China, part I: Inventory and PM_2.5 sources apportionment

This article uses the WRF-CMAQ model to systematically study the source apportionment of PM_2.5 under typical meteorological conditions in the dry season (November 2010) in the Pearl River Delta (PRD). According to the geographical location and the relative magnitude of pollutant emission, Guangdong Province is divided into eight subdomains for source apportionment study. The Brute-Force Method (BFM) method was implemented to simulate the contribution from different regions to the PM_2.5 pollution in the PRD. Results show that the industrial sources accounted for the largest proportion. For emission species, the total amount of NO_x and VOC in Guangdong Province, and NH₃ and VOC in Hunan Province are relatively larger. In Guangdong Province, the emission of SO₂, NO_x and VOC in the PRD are relatively larger, and the NH₃ emissions are higher outside the PRD. In northerly-controlled episodes, model simulations demonstrate that local emissions are important for PM_2.5 pollution in Guangzhou and Foshan. Meanwhile, emissions from Dongguan and Huizhou (DH), and out of Guangdong Province (SW) are important contributors for PM_2.5 pollution in Guangzhou. For PM_2.5 pollution in Foshan, emissions in Guangzhou and DH are the major contributors. In addition, high contribution ratio from DH only occurs in severe pollution periods. In southerly-controlled episode, contribution from the southern PRD increases. Local emissions and emissions from Shenzhen, DH, Zhuhai-Jiangmen-Zhongshan (ZJZ) are the major contributors. Regional contribution to the chemical compositions of PM_2.5 indicates that the sources of chemical components are similar to those of PM_2.5. In particular, SO₄^2- is mainly sourced from emissions out of Guangdong Province, while the NO^3- and NH⁴⁺ are more linked to agricultural emissions.