2016～2017年采暖期华北平原东部PM2.5组分特征及来源解析

Chemical Composition Characteristics and Source Apportionment of PM2.5 During the Heating Period of 2016-2017 in the Eastern Part of the North China Plain

为掌握华北平原东部地区大气细颗粒物(PM2. 5)的污染特征与来源,本研究对2016年和2017年这2年采暖期衡水市、沧州市、济南市、德州市、滨州市、淄博市和聊城市的大气细颗粒物、组分特征和来源进行对比分析.结果表明,2016年和2017年采暖期该区域ρ(PM2. 5)日均值分别为137. 23μg·m-3和111. 83μg·m-3,分别超过《环境空气质量标准》(GB 3095-2012)日均二级标准限值1. 8倍和1. 5倍;水溶性离子质量浓度分别占ρ(PM2. 5)的53. 32%和47. 04%,二次无机离子(SNA)为主要离子组分;NO3-/SO24-比值从1. 35上升至1. 60,同时Cl-浓度下降,表明燃煤源贡献降低;二次有机碳(SOC)在有机碳(OC)中的占比分别为71. 63%和55. 35%,说明该区域二次有机碳占比明显降低;特征元素Fe/Al、Ba/Ni对比分析表明,2017年采暖期机动车源和扬尘源贡献同比上升;后向轨迹结果表明,该区域污染气团主要源于西北方向,但来源于江苏、安徽等地的污染气团携带的颗粒物浓度最高.

To study the composition characteristics and source apportionment of PM2.5 in the eastern part of the North China Plain,manual samples during the two-year heating period of 2016 and 2017 were collected in seven cities,including Hengshui,Cangzhou,Ji'nan,Dezhou,Binzhou,Zibo,and Liaocheng.The results showed that the average values ofρ(PM2.5)during the observation periods were 137.23μg·m-3 and 111.83μg·m-3,respectively,which exceeded the daily average secondary standard limit of GB 3095-2012“Environmental Air Quality Standard”by 1.8 and 1.5 times,respectively.The mean mass of water-soluble ions accounted for 53.32%and 47.04%ofρ(PM2.5),respectively,of which SNA(NO-3,SO2-4,and NH+4)were the main ions.During the 2016 and 2017 observation periods,NO-3/SO2-4 increased from 1.35 to 1.60,while the concentration of Cl-decreased,indicating a decrease in the impact of coal burning.The proportions of secondary organic carbon(SOC)in organic carbon(OC)were 71.63%and 55.35%,respectively,indicating the source of secondary organic carbon had decreased.Analysis of characteristic elements Fe/Al and Ba/Ni showed that dust sources and vehicle sources had increased significantly.The backward trajectories of air mass results showed that the polluted air mass mainly came from the northwest direction during the observation period.However,the PM2.5 concentration was highest when the air mass came from the Anhui and Jiangsu provinces.