京津冀区域PM2.5及二次无机组分污染特征研究

选取北京、石家庄和唐山作为京津冀区域典型城市，基于实地样品采集和组分分析结果，探讨PM_2.5组分中二次无机水溶性离子（SNA）浓度变化特征，并利用空气质量模型模拟结果分析重污染前后京津冀地区各类污染源大气污染物排放对PM_2.5和SNA质量浓度的贡献.结果显示：3个城市PM_2.5质量浓度整体呈现逐年下降的趋势，多数情况下SO₄^2-、NO₃^-和NH₄⁺浓度极大值同时出现在冬季，PM_2.5化学组分较为稳定.相对于常规时段，重污染期间SO₄^2-、NO₃^-和NH₄⁺质量浓度明显增加，重污染前一天SNA浓度占PM_2.5比值达到最高.重污染的形成是本地源排放和外来区域传输共同作用的结果，外来源对NO₃^-的贡献整体高于SO₄^2-和NH₄⁺.交通源、居民源和工业源对PM_2.5、SO₄^2-和NO₃^-浓度贡献最高，NH₄⁺主要来自居民源的排放.

Pollution characteristic of PM2.5 and secondary inorganic ions in Beijing-Tianjin-Hebei region

Beijing,Shijiazhuang and Tangshan were selected as the typical cities in the Beijing-Tianjin-Hebei region to investigate the seasonal variation characteristics of secondary water-soluble inorganic ions and compare the pollution characteristics and physicochemical property of the secondary water-soluble ions between heavy pollution period and other periods.Then CAMx-PSAT model was applied to quantitatively analyze the contribution on PM_2.5 and SNA concentration from pollution sources in BTH region during different seasons.Results showed that PM_2.5 concentration in these cities decreased year by year,and the maximum of SO₄^2-,NO₃^- and NH₄⁺ concentration mostly in winter at the same time,illustrating the related correlation of their concentrations.The mass concentrations of SO₄^2-,NO₃^- and NH₄⁺increased significantly during heavy pollution period compared with other periods.The largest concentration ratio of SNA appeared in 1~2 days before heavy pollution days.The formation of heavy pollution was the combined effects of local pollutant emission and external source region transport.The contribution of external sources to NO₃^- was higher than that of SO₄^2- and NH₄⁺.In addition,the concentration of PM_2.5,SO₄^2- and NO₃^- were mostly contributed from traffic sources,resident sources and industrial sources,and the resident sources were the most important contributor for NH₄⁺ concentration.