摘要
使用在线分析仪于2018年7月至2019年2月在北京城区对大气中的苯系物(BTEX)进行连续监测.监测期间BTEX平均体积分数为(5.05±5.23)×10^(-9),其中苯、甲苯、乙苯、间/对二甲苯及邻二甲苯的体积分数分别为(1.51±1.70)×10^(-9)、(2.22±2.05)×10^(-9)、(0.38±0.46)×10^(-9)、(0.53±0.56)×10^(-9)和(0.41±0.46)×10^(-9).BTEX浓度低于早前研究,季节变化也有所差异.BTEX日变化特征为白天浓度低于夜晚,夏季、秋季和冬季的浓度最低值分别出现在15:00、14:00和13:00;在冬季交通早高峰,BTEX出现明显的次峰值.根据最大增量反应活性法计算了BTEX各组分的臭氧生成潜势(OFP),其中甲苯OFP值最大,为(6.86±5.54)×10^(-9).OFP值的季节变化特征与BTEX浓度变化一致,表现为秋季>冬季>夏季.通过特征物种比值法发现北京城区夏季受燃煤和溶剂挥发等综合影响,秋季主要受交通源排放的影响,冬季则主要受燃煤排放的影响.通过间/对二甲苯与乙苯比值发现北京夏季和冬季BTEX以新鲜排放源为主,秋季以老化气团为主.
BTEX in urban Beijing had been continuously measured using an on-line analyzer from July 2018 to February 2019.The average hourly mean mixing ratios of BTEX,benzene,toluene,ethylbenzene,m/p-xylene,and o-xylene were(5.05±5.23)×10^(-9),(1.51±1.70)×10^(-9),(2.22±2.05)×10^(-9),(0.38±0.46)×10^(-9),(0.53±0.56)×10^(-9)and(0.41±0.46)×10^(-9),respectively.Compared with earlier studies in urban Beijing,the concentrations of BTEX in our study showed lower values,and the seasonal changes also varied.The average diurnal variations were characterized by lower concentrations during daytime than at night,with the lowest concentrations occurring at around15:00,14:00,and 13:00 in summer,autumn,and winter,respectively.In the morning rush hours,there was an obvious BTEX peak in winter.According to the maximum incremental reaction activity method,the ozone formation potentials(OFP)of the BTEX components were obtained,of which the maximum value was found in toluene with a value of(6.86±5.54)×10^(-9).The seasonal variation in OFP values was consistent with BTEX concentrations,with higher values in autumn than in winter and summer.Through the characteristic species ratio method,it was found that BTEX were mainly affected by emissions from coal burning and solvent evaporation in summer,from traffic sources in autumn,and from coal burning in winter.BTEX were dominated by fresh emissions in summer and winter,and influenced by aged air in autumn according to the analysis on xylene to ethylbenzene ratios.
作者
张超
林伟立
韩婷婷
马志强
郭淑政
ZHANG Chao;LIN Weili;HAN Tingting;MA Zhiqiang;GUO Shuzheng(College of Life and Environmental Sciences,Minzu University of China,Beijing,100081,China;Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei,Beijing,100089,China)
出处
《环境化学》
CAS
CSCD
北大核心
2022年第2期460-469,共10页
Environmental Chemistry
基金
国家自然科学基金(91744206)
北京市科委项目(Z181100005418016)资助。
关键词
苯系物
变化特征
臭氧生成潜势
特征物种比值
BTEX
variations
ozone formation potential
characteristic species ratio
