A Typical Formation Mechanism of Heavy Haze-Fog Induced by Coal Combustion in an Inland City in North-Western China

Abstract

PM 2.5 , TSP, and the pollutant gases over Urumqi, an inland city near the Asian dust source region in north-western China, were measured for an entire year from March, 2008 to February, 2009. The chemical compositions of all these samples with daily visibilities were investigated for the sources and formation mechanisms of aerosol and the relationship of the optical property with various components in aerosols. The sources of the air pollutants that caused severe haze in Urumqi were clarified. It was found that the concentrations of SO 4 2-, Cl -, NH 4 + , and Na + in PM 2.5 in the heating period were more than 9 times of those in the non-heating period. The concentrations of total water soluble inorganic ions (TWSII) in PM 2.5 and TSP in the heating period were 7.5 and 5.5 times of those in the non-heating period. The enrichment factors of the pollution elements, e.g., S, Cd, As, Zn, Pb, Cu, Cr, and Na in PM 2.5 in the heating period were 3-13 times of those in the non-heating period. The formation mechanism of the severe haze and the micro-mechanism of the visibility reduction in Urumqi in the heating period, especially in winter, were quantitatively revealed. SNA (the three secondary inorganic ions, SO 4 2-, NO 3 -, and NH 4 + ), organic matter (OM), and chloride (Cl -) in PM 2.5 were the three main components to cause aerosol extinction in Urumqi. The contributions of SNA, OM, and Cl -to aerosol extinction, i.e., to visibility reduction, were 57%, 20%, and 12% during the heating period from October 15 to April 15, and 67%, 17%, and 12% in winter, respectively. It was evident that the major source of the air pollutants that caused severe haze in Urumqi was from coal combustion, for most of these ions and pollution elements in aerosols were emitted from coal burning. The control of the quality and quantity of coal burning is the key to improve the air quality and the atmospheric visibility in Urumqi.

Spatio-Temporal Characteristics of Air Quality Index (AQI) over Northwest China

“…PM 2.5 mainly originates from industrial activities, coal consumption, power generation, biomass burning, automobile exhausts, construction activities, road dust, etc. [28][29][30][50][51][52]. From 2015 to 2018, the average concentration of PM 2.5 decreased in all the cities except a few cities (Changji, Ili, Shihezi, Wujiaqu) in the northern part of XJ.…”

“…In terms of seasonality, PM 2.5 , PM 10 , SO 2 , NO 2 , and CO experienced the same seasonal variation, e.g., highest in winter and lowest in summer. Higher pollution in winter is associated with increased coal combustion, civil heating, power generation, fossil fuel burning, industrial activity, vehicular exhausts, and adverse/stagnant meteorology [13][14][15][26][27][28][29][30][50][51][52][71][72][73][74][75]. In the case of PM 10 , higher pollution levels also occurred from March to May (spring) due to haze events [76,77].…”

Spatiotemporal Variation and Influencing Factors of TSP and Anions in Coastal Atmosphere of Zhanjiang City, China

“…The natural influence is mainly from the accumulation of atmospheric particulate matter caused by wind and dust in the west and north direction [ 51 ]. Compared with natural sources of impact, human sources of impact are more complex, including industrial boilers [ 52 ], waste incineration [ 53 , 54 ], household heating [ 55 ], construction [ 56 ], and mining [ 57 , 58 ]. In general, TSP is mainly a land-based pollutant.…”

Characteristics of long-range transported PM2.5 at a coastal city using the single particle aerosol mass spectrometry

“…As noted in previous research, off-line monitoring is a widely-used method for PM mass analyses [6]. However, this method has been found to have deficiencies in many aspects, such as low resolutions, the sampling pollution and a poor efficiency [7].…”