[Water-soluble chloride in aerosol PM10 in Beijing]

Water-soluble chloride is one of the most important components in aerosols. The chloride in PM10 measured from January to December 2004 in Beijing was determined using a system by combing rapid collection of fine particles and ion chromatography (RCFP-IC). The results showed that the annual average concentration of water-soluble chloride at the urban area in Beijing was about (3.1 +/- 1.7) microg x m(-3); the average concentration of chloride during the heating period was (4.6 +/- 2.1) microg m(-3) while it was (2.6 +/- 1.6) microg x m(-3) during the period no heating. The lowest concentration of (1.3 +/- 0.8) microg x m(-3) appeared in May, and the highest concentration appeared of (5.8 +/- 5.3) microg x m(-3) in December. Trends of the diurnal variation of water-soluble chloride depended on seasons. In autumn and winter, the higher concentration appeared in the daytime and the lower concentration appeared at night. In spring and summer, the higher concentration appeared at forenoon and the lower appeared at afternoon. Overall, the concentration of chloride in autumn and winter was higher than in spring and summer.