乌鲁木齐市采暖期与非采暖期大气PM_(2.5)和PM_(10)中水溶性离子特征分析

Water-soluble ions pollution characteristics of the atmospheric particles(PM_(2.5) and PM_(10)) in Urumqi during the heating and non-heating periods

为了解乌鲁木齐市采暖期和非采暖期大气颗粒物(PM_(2.5)和PM_(10))水溶性离子污染特征,于2015年在乌鲁木齐市采集两个时期大气颗粒物样品,采用离子色谱仪(IC)等仪器对PM_(2.5)和PM_(10)中的9种水溶性离子进行了定量分析。结果表明,乌鲁木齐市采暖期PM_(2.5)与PM_(10)中水溶性离子平均质量浓度分别为(76.26±36.15)μg/m3和(88.94±41.43)μg/m3,约为非采暖期的2倍,主要水溶性离子是SO2-4、NH_4^+、NO-3和Cl-,这4种水溶性离子分别占PM_(2.5)和PM_(10)中总水溶性离子的88.91%和90.03%;非采暖期PM_(2.5)与PM_(10)中水溶性离子平均质量浓度分别为(37.62±14.03)μg/m3和(44.12±16.79)μg/m3,主要水溶性离子是SO2-4、NH_4^+、NO-3和Ca2+,这4种水溶性离子分别占PM_(2.5)和PM_(10)中总水溶性离子的88.18%和86.96%。采暖期PM_(2.5)和PM_(10)中NH_4^+、SO2-4、NO-3三者之间有强相关性,它们可能具有相似的来源;而非采暖期NH_4^+和SO2-4、Cl-的相关性最强,非采暖期NH_4^+在PM_(2.5)和PM_(10)中主要以(NH_4)2SO4和NH_4Cl形式存在。采暖期和非采暖期乌鲁木齐市[NO-3]/[SO2-4]均小于1,推测乌鲁木齐市颗粒物污染可能主要来源于固定排放源。

The paper intends to investigate the pollution characteristic features of the water-soluble ions in the atmospheric particles in the capital city of Urumqi,Xinjiang. For the investigation purpose,we have collected the atmospheric particle samples of PM2.5 and PM10 during the heating period and non-heating period of the city in 2015. And,then,we have made an analysis of the mass concentration composition of the 9 kinds of water-soluble ions（ K~＋,Na~＋,Mg^（2 ＋） ,Ca^（2＋）,NH4~＋,F-,NO-3,Cl-,SO2-4）in PM2.5 and PM10 samples quantitatively via chromatographs,known as IC,ICP-OES and UV-VIS. The results of our analysis show that the mass concentrations of 9 sorts of ions in PM2.5 and PM10 in the heating period turn out to be about twice as much as those for the non-heating period. More clearly speaking,in the heating period,the total average mass concentrations of the 9 ions account for（ 76. 26 ± 36. 15） μg/m3 in PM2.5,and（ 88. 94 ±41. 43） μg/m3 in PM10,accordingly,whereas the main watersoluble ions of SO2-4, NH4~＋, NO-3 and Cl-, are equal to88. 91% in PM2.5 and 90. 03% in PM10. In comparison,in the no-heat supply period,the total average mass concentration of the9 ions remains at about（ 37. 62 ± 14. 03） μg/m3 in PM2.5,and（ 44. 12 ± 16. 79） μg/m3 in PM10,respectively,with the main water-soluble ions being SO2-4,NH4~＋,NO-3 and Ca2 ＋,which account for 88. 18% in PM2.5 and 86. 96% in PM10. Thus,NH4~＋,SO2-4,NO-3 in PM2.5 and in PM10 can be found strongly interrelated with each other in the heat-supply period,signifying that the3 water-soluble ions have approximately the same pollution source. On the other hand,NH4~＋,SO2-4 and Cl-can also be found strongly mutually related in the non-heating period,for NH4~＋ mainly exist in the form of（ NH4）2 SO4 and NH4 Cl compounds in PM2.5 and PM10. Therefore,whether during the heating period or non-heating period in the city,the rate of NO-3 to SO2-4 turn out to be less than 1,which suggests that the particulate pollutants of the city should be categorized into the stationary one.