Micro-Morphological Characteristics and Size Distribution of PM2.5 in the Kuitun-Dushanzi Region of Xinjiang, China

The micro-morphological characteristics of PM2.5, collected in the Kuitun-Dushanzi petrochemical area of the Xinjiang Uygur Autonomous Region, China, were studied using a high-resolution field emission scanning electron microscope with energy dispersive X-ray spectroscopy (FESEM-EDX). The individual particle types of PM2.5 were identified, including mineral particles (regular minerals and irregular minerals), spherical particles (coal-fired fly ash and some secondary particles), soot aggregates, and other particles (some particles remained unclassified). Factories, power plants, vehicle emissions, and road dust were major sources of PM2.5 in the Kuitun-Dushanzi petrochemical area. Vehicle exhaust and waste gas from a power plant were defined as primary sources of mineral particles. Wind speed in September which was higher than July during the sampling time leads to the lower concentration of regular mineral particles since high wind speeds would reduce the chance of secondary particle generation. As a high wind speed would also easily diffuse the fine particles, the coarse-grained mineral particles had the highest percentages in September; the chain-like soot aggregates and the compact soot aggregates were the majority of all kinds of particles. The sizes of various particles in July and September primarily ranged from 0.1 to 0.5 µm.