Abstract
PM2.5 and PM10 samples were collected simultaneously in each season in Beijing, Tianjin and Shijiazhuang to identify the characteristics of water-soluble ion compositions in the North China Plain. The water-soluble ions displayed significant seasonal variation. The dominant ions were NO3 −, SO4 2−, NH4 + and Cl−, accounting for more than 90% and 86% to the mass of total water-soluble ions in PM2.5 and PM10, respectively. The anion/cation ratio indicated that the ion acidity of each city varied both between sites and seasonally. Over 50% of the ion species were enriched in small particles ≤1 µm in diameter. The [NO3 −]/[SO4 2−] ratio indicated that vehicles accounted for the majority of the particulate pollution in Beijing. Shijiazhuang, a city highly reliant on coal combustion, had a higher SO4 2− concentration.
Highlights
Particulate matter (PM) in the atmosphere originates from either direct emission or physical and chemical transformation of gaseous pollutants [1,2,3]
Significant seasonal variation in the water-soluble compositions of PM2.5 and PM10 were identified in each city (Table 2)
The concentrations of water-soluble ions in both PM2.5 and PM10 displayed a significant variation with season, in the order spring. winter. summer. autumn
Summary
Particulate matter (PM) in the atmosphere originates from either direct emission or physical and chemical transformation of gaseous pollutants [1,2,3]. Air quality has become an increasing public health concern since a series of heavy pollutions of fine particulate matter (PM2.5, particles #2.5 mm in diameter) occurred in Beijing in 2011 winter. The majority of research on this region has focused on the composition [25], seasonal variation [26] and source of the particulate matter [27]. A few studies addressed PM concentrations across the major cities in North China Plain [36] These studies seldom referred to the national atmospheric background status at the same period. Program in 2013, focuses on the water-soluble ion compositions and their variation in particulate matter in 3 metropolises in North China area. Data from national atmospheric background sites are referred at the same sampling periods
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