杭州市大气PM2.5中部分元素的分布

Carbon,Nitrogen,Hydrogen and Heavy Metals in Airborne PM2.5 in Hangzhou

目的探讨杭州市大气PM2.5中重金属和碳、氮、氢的污染状况。方法于2004年4月—2005年3月,在杭州市中心、市中心以东4km处、市中心东北方向3km处设置3个采样点,用中流量气溶胶采样器采集大气中的PM2.5,以燃烧法和微波消解-电感耦合等离子体质谱法分别检测碳、氮、氢和重金属的组成。结果杭州市中心和市区东北部大气PM2.5中,碳、氮、氢的平均浓度分别为30.3～30.8μg/m3、13.9～14.7μg/m3、7.9～8.9μg/m3。全市大气PM2.5中碳、氮、氢的平均质量百分含量分别为27.8%,12.8%,8.1%。总无机氮/总有机氮、总有机氢/总无机氢的平均比值分别为2.2～3.5、3.5～3.6。PM2.5中11种元素的含量较高,其中Zn、Pb、Cu、Mn的含量在200～11500mg/kg之间,Cr、Ni、Se、Mo、Cd、Sb在17～108mg/kg之间,Ag只有6～8mg/kg。这11种元素的平均质量百分总含量合计约为1.7%～2.0%。结论碳是杭州市大气PM2.5的重要组成部分,氮、氢分别主要以无机氮和有机氢的形式存在,Zn、Pb、Cu、Mn是主要重金属污染元素。

Objective To analyze the concentration of heavy metal elements, C, N and H in PM2.5 in the atmosphere in Hangzhou. Methods Midflow samplers were used to collect the samples in Hangzhou city, the element analyzer and microwave digestion ICP-MS were applied to test the samples. Results The average concentrations of N, C, H were 13.9-14.7, 30.3-30.8 and 7.9-8.9 μg/m3 respectively in the central and northern east areas. The average mass percent values for the three elements(N、C、H) in the city were 12.8%, 27.8% and 8.1% respectively. The average ratios of total inorganic nitrogen to total organic nitrogen (IN/ON) and total organic hydrogen to total inorganic hydrogen (OH/IH) varied in the range of 2.2-3.5 and 3.5-3.6. Eleven elements showed a higher concentration in PM2.5, in which the values of Zn, Pb, Cu and Mn were all more than 200-11 500 mg/kg and the values of Cr, Ni, Se, Mo, Cd and Sb were 17-108 mg/kg, and that was only 6-8 mg/kg for Ag. The levels of average mass percent of all the metal elements were 1.7%-2.0%. Conclusion Carbon is one of important components in PM2.5 in Hangzhou. N and H exist mainly in the form of inorganic and organic compounds respectively. Zn, Pb, Cu, Mn are major heavy metal elements in PM2.5.