Vertical characteristics of levels and potential sources of water-soluble ions in PM sub(10) in a Chinese megacity

To investigate the vertical characteristics of ions in PM sub(10) as well as the contributions and possible locations of their sources, eight water-soluble ions were measured at four heights simultaneously along a meteorological tower in Tianjin, China. The total ion concentrations showed a general...

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Bibliographic Details
Published in:The Science of the total environment 2013-03, Vol.447, p.1-9
Main Authors: Tian, Ying-Ze, Shi, Guo-Liang, Han, Su-Qin, Zhang, Yu-Fen, Feng, Yin-Chang, Liu, Gui-Rong, Gao, Li-Jie, Wu, Jian-Hui, Zhu, Tan
Format: Article
Language:English
Subjects:
China
Correlation
Ion concentration
Management
Principal component analysis
Regression
Towers
Trends
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Summary:To investigate the vertical characteristics of ions in PM sub(10) as well as the contributions and possible locations of their sources, eight water-soluble ions were measured at four heights simultaneously along a meteorological tower in Tianjin, China. The total ion concentrations showed a general decreasing trend with increasing height, ranging from 64.94 mu gm super(-3) at 10m to 44.56 mu gm super(-3) at 220m. NH super(+) sub(4), SO super(2)- sub(4) and NO super(-) sub(3) showed higher height-to-height correlations. In addition, relationships between ions are discussed using Pearson correlation coefficients and hierarchical clustering analysis (HCA), which implied that, for each height, the correlations among NH super(+) sub(4), SO super(2)- sub(4) and NO super(-) sub(3) were higher. Finally, sources were identified qualitatively by the ratio of certain ions and quantitatively by principal component analysis/multiple linear regression (PCA/MLR) and positive matrix factorisation (PMF). Secondary sources played a dominant role for PM sub(10) and water-soluble ions at four heights and became more important at greater heights (the percentage contributions were 43.04-66.41% for four heights by PCA/MLR and 46.93-67.62% by PMF). Then, the redistributed concentration field (RCF) combined with PCA/MLR and PMF was applied, which indicated the high potential source regions. The vertical characteristics of the levels, relationships, source contributions and locations would support the effective management of the water-soluble ions in particulate matter.
ISSN:0048-9697
DOI:10.1016/j.scitotenv.2012.12.071