Liu Jia-Shu, Gu Yuan, Ma Shuai-Shuai, Su Ya-Lan, Ye Zhao-Lian
School of Chemical and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China.
Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China.
Huan Jing Ke Xue. 2018 Mar 8;39(3):980-989. doi: 10.13227/j.hjkx.201707141.
To investigate the day-night variation characteristics of inorganic components in atmospheric aerosol, PM samples were continuously collected for one month in Changzhou during summer and winter. Eleven water-soluble ions (WSⅡs) and 13 metal elements were compared in terms of their day-night character and sources. The results indicated that the day time average PM mass concentration was higher than the night time, while the percentage of the total WSⅡs in PM during the night was higher. The total WSⅡs fractions in PM were higher in winter (44%-45%) compared to summer (31%-36%), with an opposite seasonal character for metal elements (winter day 3.03%, winter night 2.29%, summer day 4.40%, summer night 4.51%). SO, NO, and NH, were the three main secondary ions, comprising 77%-85% of the total WSⅡs, suggesting that air pollution in Changzhou exhibits complex pollution characteristics dominated by secondary processes. The day time SO/WSⅡs ratio (49.0%) was slightly higher than that of the night (41.1%) due to the photochemical reaction under stronger solar radiation, while the lower NO(1.98 μg·m) in the day compared to the night (5.10 μg·m) was attributed to the decomposition of NHNO during summer days. A good linear correlation among NH, SO and NO, accompanied by a ratio of predicted NH to measured NH near 1, illustrated that NH ions mainly existed in the form of (NH)SO, NHNO, and NHCl. It was concluded from the ion balance that PM was weakly alkaline in summer but neutral in winter. Fe, Al, and Zn were the largest contributors to the total metal elements, with higher concentrations of Fe and Al and lower levels of Zn in the day time. A correlation coefficient analysis and principle component analysis revealed that inorganic components come from sources that include secondary aerosol formation, suspended dust, and vehicle emissions, but there is some seasonal variation and day-night differences.
为研究大气气溶胶中无机成分的昼夜变化特征，于夏季和冬季在常州连续采集了1个月的PM样本。比较了11种水溶性离子（WSⅡs）和13种金属元素的昼夜特征及来源。结果表明，白天PM质量浓度平均值高于夜间，而夜间PM中WSⅡs总量的占比更高。与夏季（31%-36%）相比，冬季PM中WSⅡs总量占比更高（44%-45%），金属元素则呈现相反的季节特征（冬季白天3.03%，冬季夜间2.29%，夏季白天4.40%，夏季夜间4.51%）。SO、NO和NH是三种主要的二次离子，占WSⅡs总量的77%-85%，表明常州的空气污染呈现以二次过程为主导的复杂污染特征。由于较强太阳辐射下的光化学反应，白天SO/WSⅡs比值（49.0%）略高于夜间（41.1%），而夏季白天NO（1.98μg·m）低于夜间（5.10μg·m）是由于NHNO的分解。NH、SO和NO之间存在良好的线性相关性，预测的NH与实测的NH比值接近1，说明NH离子主要以(NH)SO、NHNO和NHCl的形式存在。由离子平衡得出，夏季PM呈弱碱性，冬季呈中性。Fe、Al和Zn是金属元素总量的最大贡献者，白天Fe和Al浓度较高，Zn浓度较低。相关系数分析和主成分分析表明，无机成分来自二次气溶胶形成、扬尘和机动车排放等源，但存在一定的季节变化和昼夜差异。
