Concentrations of SO42-,NO3-,Cl- and NH4+ in atmospheric PM2.5 in Zhoushan / 预防医学

ABSTRACT

Objective@#To understand the concentrations and source of SO42-,NO3-,Cl- and NH4+ in atmospheric PM2.5 in Zhoushan,and to provide reference for controlling PM2.5 and formulating effective environmental protection measures.@*Methods@#Monitoring sites in new districts of Zhoushan were set up to continuously collect PM2.5 from 10th to 16th of each month and under the hazy weather during 2015-2016（AQI > 200）. The mass concentration of PM2.5 was measured by weighing method,and the concentrations of SO42-,NO3-,Cl- and NH4+ in PM2.5 components was detected by ion chromatography. @*Results@#The average daily concentration of PM2.5 in Zhoushan from 2015 to 2016 was（40.91±27.39）μg/m3. The concentration of the four water-soluble non-metal ions in PM2.5 components was 3.56-103.03 μg/m3,with an average of（23.06±20.00）μg/m3,accounting for about 56.64% of PM2.5 contents. The average monthly concentration of SO42- was the highest[（10.35±6.48）μg/m3],while the average monthly concentration of Cl- was the lowest [（0.49±0.73）μg/m3]. The concentration of the four ions was the highest in winter[（37.56±27.74）μg/m3]and the lowest in summer[（12.32±5.88）μg/m3]. The differences between different seasons was statistically significant（P<0.05）. The highest concentration of NO3- occurred in winter,which was（14.48±13.28）μg/m3. The concentration ratio of NO3- to SO42- ranged from 0 to 2.58,with an average of 0.55. There were 28 days（14.74%）with the ratio greater than one,22 days of which was in winter.@*Conclusion@#The concentration of SO42- was the highest and Cl- was the lowest in atmospheric PM2.5 in Zhoushan. The highest concentration of the four ions occurred in winter. The concentration of NO3- in winter was higher than that of SO42-,suggesting that motor vehicle exhaust might be the main source of PM2.5 in winter.