论文部分内容阅读
为探讨西安大气颗粒物中水溶性离子及含碳组分的季节变化和昼夜变化特征及来源,于2006.12-20--2007.1_21(冬季)和2007-7-1-2007.8.1(夏季)连续采集大气可吸入颗粒物(PM100)样品,分析其中Na+、NH4+、K+、Mg2+、Ca2++、F-、C1-、NO-3;和SO2-4;一共9种水溶性离子及oc和Ec的昼夜浓度.结果显示:冬季白天PM.及其中总水溶性离子、OC和EC的浓度均值分别为455.0±191.6Pug·m-3、139.7±73.9μg·m-3、61.7±29.7lμg·m-3和7.4±2.1μg·m-3,夜晚分别为448.7±167.9μg·m-3、140.0±45.8pug·m-3、65.4±24.8μg·m-3和6.9±1.9μg·m-3,对应夏季白天分别为219.4±84.1μg·m-3、112.1±56.5μg·m-3、17.6±4.7μg·m-3.和4.5±1.3μg·m-3,夜晚为234.9±67.3μg·1/1、106.4±40.3μg·m~、21.1±7.7lμg·m-3和6.6±2.1μg· m-3.双对数散点图分析显示,冬季(CD=0.060)和夏季(CD=0.156)PM.中化学组分的昼夜污染差异均很小.冬季白天OC/EC比值明显低于夜晚,夏季昼夜变化没有冬季明显,且冬季OC与EC的相关性较夏季差,表明冬季碳气溶胶来源较夏季复杂.冬季和夏季PM10.中NO10/SO3-的质量浓度比值分别为0.47和0.44,说明燃煤仍然是西安大气PM10.中水溶性离子的主要来源.冬季相对较高的K+和OC浓度指示了生物质燃烧和燃煤对PM10.的重要贡献. “,”The purpose of this study was to investigate the seasonal and day-night difference of water-soluble ions and carbonaceous components in PMI0 during winter and summer over Xi'an. The mass concentrations of 9 water-soluble ions ( Na +, NH4+, K +, Mg2+, Ca2+, F-, CI-, NO3 and SO2- 4), OC, and EC in PM,0 samples were measured. PMI0, total water-soluble ions, OC, and EC concentrations in winter were 455.0 _+191.6 μg.m-3, 139.7 _+73.9 μg-m-3 , 61.7 +29.7 p,g'm-3 and 7.4 ±2. lp, m-3 during daytime, and 448.7 _+ 167.9 μg.m-3, 140.0 _+45.8 μg·m-3, 65.4 _+ 24.8 μg·m-3 and 6.9 _+ 1.9 μg-m-3 in nighttime, respectively. In contrast, they were 219.4 ± 84.1 μg·m-3, 112.1 ±56.5 μg·m-3, 17.+±4.7± μg-m-3and4.5±1.3 μg·m-3 in summer daytime, and were234.9±67 3 μg-m-3 106.4±40.3 μg-m·3 21 1±7.7 μg·m-3 and6.6±2.1 μg·m-3μ m-3in summer nighttime. In both winter (CD = 0. 060 ) and summer (CD = 0. 156 ), there was no significant difference between daytime and nighttime mass concentrations of PMI0 and major chemical species. OC/EC ratio during daytime was lower than nighttime in winter, while the day-night ratio was similar in summer. In addition, the correlation coefficient between OC and EC in winter was lower than that in