北京灰霾天PM_(2.5)中有机官能团和无机离子的ATR-FTIR研究

采用傅里叶变换衰减全反射红外光谱法(ATR-FTIR)研究北京西北城区灰霾天气下PM_(2.5)中有机官能团(R-OH羟基、R-CH脂肪族碳氢基、R-CO-羰基、R-NO2硝基官能团)和无机离子(NH_4~+、SO_4~(2-)、NO_3~-)的变化规律.结果表明,PM_(2.5)中无机离子(NH_4~+、SO_4~(2-)、NO_3~-)的ATR-FTIR吸收峰值高于有机官能团(R-CH,R-CO-,R-NO_2,R-OH)的峰值;有机官能团R-CH的吸收峰峰值高于R-CO-和R-NO_2官能团的吸收峰,R-OH官能团的吸收峰峰值最低.灰霾天PM_(2.5)中各有机官能团和无机离子的ATR-FTIR吸收峰值明显高于非灰霾天.说明灰霾天气下PM_(2.5)中这些官能团及无机离子的质量浓度均高于非灰霾天.灰霾天PM_(2.5)中无机离子(NH_4~+、SO_4~(2-)、NO_3~-)质量浓度高于有机官能团(R-CH,R-CO-,R-NO_2,R-OH)的质量浓度,且有机官能团以R-CH为主,R-CO-,R-NO_2次之,R-OH最少.

ATR-FTIR characterization of organic functional groups and inorganic ions of the haze PM2.5 in Beijing

An Attenuated Total Reflectance-Fourier Transform Infrared (ART-FTIR) spectroscopy was used to measure the functional groups (R-NO₂, R-CO-, R-CH and R-OH) and inorganic ions (SO₄^2-, NO₃^- and NH₄⁺) in PM_2.5 collected in the northwest of Beijing during haze days. The absorption peaks of inorganic ions (NH₄⁺, SO₄^2- and NO₃^-) were higher than those of functional groups (R-NO₂, R-CO-, R-CH and R-OH), the absorption peak of R-CH was higher than those of R-NO₂ and R-CO-, and the absorption peak of R-OH was lowest. The absorption peaks of these functional groups and inorganic ions of the PM_2.5 in haze days were higher than those in the non-haze days, indicating that the mass concentrations of these functional groups and inorganic ions in haze days were higher than those in the non-haze days. During haze days, the mass concentrations of the inorganic ions (NH₄⁺, SO₄^2- and NO₃^-) were higher than those of functional groups (R-NO₂, R-CO-, R-CH and R-OH), the mass concentration of R-CH was higher than those of R-NO₂ and R-CO-, and the mass concentration of R-OH was lowest.