Chemical composition and source apportionment of PM_1 and PM_(2.5) in a national coal chemical industrial base of the Golden Energy Triangle, Northwest China

摘要

As part of the Energy Golden Triangle in northwest China and the largest coal-to-liquids industry in the world, the emission and contamination of fine particles in the Ningdong National Energy and Chemical Industrial Base (NECIB) are unknown. There are also large knowledge gaps in the association of air pollution with coal-to-liquids industry. This paper reports the chemical composition and source apportionment of PM1 and PM2.5 collected at two industrial sites Yinglite (YLT) and Baofeng (BF) from a field campaign during summer 2016 and winter 2017. Major chemical components in PM1 and PM2.5, including carbonaceous aerosols, water-soluble inorganic ions, and metal elements were analyzed. The Positive Matrix Factorization (PMF) model and the ISORROPIA II thermodynamic equilibrium model were used to track possible sources and contributions of these chemical components to the formation of the two fine particles. The results identified four primary sources of the fine particles, including vehicle emissions, biomass burning and waste incineration, the secondary aerosols and coal combustion, and soil dust. The PM1 and PM2.5 concentrations were higher in winter than summer. The summed secondary inorganic and carbonaceous aerosols accounted for 36.1-40.0% of PM2.5 mass. The total mass of chemical components identified in the source apportionment only explained about 64.2 to 72.4% of the PM2.5 mass. These results imply some missing sources in this large-scale coal chemical industry base. A coupled weather forecasting and atmospheric chemistry model WRF-Chem was employed to simulate the PM2.5 mass and concentrations of OC and EC, and to examine the origins of PM2.5 across the NECIB. The modeled concentrations of OC and EC were consistent with the sampled data, but the modeled mass of PM2.5 is lower considerably than the measurements, again suggesting unknown sources of fine particles in this energy industrial base. (C) 2018 Elsevier B.V. All rights reserved.