北京市室内外PM_(2.5)中有机碳和元素碳分布特征研究

Characteristics of organic and elemental carbon in the indoor/outdoor air PM_(2.5) in Beijing

目的研究室内外PM_(2.5)中有机碳(organic carbon,OC)和元素碳(elemental carbon,EC)的分布特征。方法选择7个典型地区,每个地区设置室内外两个监测点,2013年5月—2014年4月连续监测PM_(2.5)中OC和EC。结果室内OC和EC年均浓度(中位值和四分位值)分别为13.4μg/m^3(8.82~26.6μg/m^3)和3.79μg/m^3(2.09~6.98μg/m^3),室外分别为15.4μg/m^3(10.6~35.2μg/m^3)和4.96μg/m^3(2.92~9.39μg/m^3),室内外OC分别占总碳的78%和73%。统计发现,碳类物质室外高于室内,OC浓度高于EC;燃煤季室外OC浓度最高,其他季节无差异;周六日室外OC浓度最高,周一至周三最低;7个典型地区室外OC浓度为:扬尘区、航油区、工业区、轻工业区>汽车尾气区、发电厂区>清洁对照区。室外OC与室外EC呈直线关系(r=0.886),室内外OC呈直线关系(r=0.915),室内外EC呈直线关系(r=0.894),碳类物质与PM_(2.5)呈直线关系(rOC-PM 2.5=0.785,rEC-PM 2.5=0.775)。夏季OC类物质室内与室外比值(I/O值)最高且与另外三季的结果有差异。燃煤季室外OC与EC比值最高,夏季最低。结论北京空气中碳类物质污染值得关注,雾霾期间应特别加强对OC防护,应采取有的放矢的措施控制OC污染。

Objective To study the characteristics of indoor/outdoor organic and elemental carbon in the PM2.5.Methods Seven type regions were selected in Beijing.The samples of OC and EC in PM2.5were collected and were measured in the indoor /outdoor of seven type areas respectively from May 2013 to April 2014.Results The overall concentrations（ median and P25-P75） of indoor OC and EC in PM2.5were 13.4 μg /m3（ 8.82- 26.6 μg/m3） and 3.79 μg /m3（ 2.09-6.98 μg /m3）,and the concentrations of outdoor OC and EC were 15.4 μg / m3（ 10.6- 35.2 μg /m3） and 4.96 μg/m3（ 2.92-9.39 μg/m3）,respectively.Indoor and outdoor OC were the dominant species occupying78% and 73% of TC,respectively.Outdoor carbonaceous matter was higher than indoor matter and the concentration of OC was higher than that of EC.The outdoor OC concentration during heating period was the highest in all seasons and the concentrations ofother seasons found no difference.The outdoor OC concentration in weekend was high,while was lower during the period of Monday to Wednesday.The outdoor OC concentrations of seven type areas were different and the pollutants from dust area,aviation fuel emissions,industry and light industry were highest,followed by ones from vehicle emissions,coal-burning power plant,and one in clean district was the lowest.There were high linear relationships between outdoor OC and outdoor EC（ r = 0.886）,between indoor OC and outdoor OC（ r = 0.915）,between indoor EC and outdoor EC（ r =0.894）,between carbonaceous matter and PM2.5（ rOC-PM2.5= 0.785,rEC-PM 2.5= 0.775）,respectively.The indoor OC to outdoor OC ratio in summer was the highest in all seasons and the ratios of other seasons found no difference.The outdoor OC to outdoor EC ratio in heating period was highest,and was lowest in summer.Conclusion We should pay attention to OC and EC pollution in Beijing air,should strengthen the protection to OC pollutants during the haze,and should take some measures to control the pollution of OC.