Characterizing ionic species in PM2:5 and PM10 in four Pearl River Delta cities,South China
LAI Sen-chao , ZOU Shi-chun , CAO Jun-ji , LEE Shun-cheng , HO Kin-fai
DOI:
Received September 07, 2006,Revised March 12, 2007, Accepted , Available online
Volume 19,2007,Pages 939-947
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PM2:5 and PM10 samples were collected at four major cities in the Pearl River Delta (PRD), South China, during winter and summer
in 2002. Six water-soluble ions, Na+, NH4
+, K+, Cl??, NO3?? and SO4
2?? were measured using ion chromatography. On average, ionic
species accounted for 53.3% and 40.5% for PM2:5 and PM10, respectively in winter and 39.4% and 35.2%, respectively in summer.
Secondary ions such as sulfate, nitrate and ammonium accounted for the major part of the total ionic species. Sulfate was the most
abundant species followed by nitrate. Overall, a regional pollution tendency was shown that there were higher concentrations of sulfate,
nitrate and ammonium in Guangzhou City than those in the other PRD cities. Significant seasonal variations were also observed
with higher levels of species in winter but lower in summer. The Asian monsoon system was favorable for removal and di usion of air
pollutants in PRD in summer while highly loading of local industrial emissions tended to deteriorate the air quality as well. NO3??/SO4
2??
ratio indicated that mobile sources have considerably contribution to the urban aerosol, and stationary sources should not be neglected.
Besides the primary emissions, complex atmospheric reactions under favorable weather conditions should be paid more attention for
the control of primary emission in the PRD region.
