2014年APEC期间北京市PM_(10)和PM_(2.5)氧化性损伤能力研究

Oxidative Capacity of the PM_(10) and PM_(2.5) in Beijing During 2014 APEC

为评估APEC会议期间联防联控措施对北京市大气可吸入颗粒物毒性的影响,采集2014年APEC会议前后3个月北京市大气PM_(10)和PM_(2.5)样品,应用质粒DNA损伤评价法来研究其氧化性损伤能力.结果表明,APEC会议期间PM_(10)对DNA的损伤率高于PM_(2.5),颗粒物对DNA损伤率随剂量的增加而增加.本研究用TD30值来指示颗粒物氧化性损伤能力,TD30为引起30%的DNA损伤率所需要的颗粒物剂量(单位为μg·m L-1),TD30值越低,颗粒物氧化性损伤能力越强,APEC会议前后样品的TD30值表现为APEC期间(11月)>APEC前(10月)>APEC后(12月),说明氧化能力APEC后>APEC前>APEC期间.用PM_(10)质量浓度乘上其在250μg·m L-1剂量下的DNA损伤率得到颗粒物暴露毒性指数TI(toxic index),与往年具有代表性月份样品的数据对比,TI大小顺序为2004年>2014年>2008年,说明大气中颗粒物暴露毒性随着政策控制力度的加大而降低.

In order to evaluate the effect of the joint air pollution prevention and control program on the toxicity of the airborne particles in Beijing during the APEC conference,we collected the PM10 and PM2.5（ particulate matter with aerodynamic diameters of less than 10μm and 2. 5 μm respectively） from October to December in the urban district of Beijing,and analyzed the oxidative capacity of the particles by plasmid scission assay. The results indicated that the oxidative capacity of PM10 was higher than that of PM2.5during the APEC conference,and that the damage rate of supercoiled DNA by the samples increased with their experimental dose levels. The TD30（ toxic dose of PM causing 30% of plasmid DNA damage,unit： μg·m L- 1） was used to indicate the oxidative capacity and the lower TD30 values indicated higher oxidative capacity. The TD30 values of the PM samples before,during,and after APEC conference displayed a descending order of during APEC（ November） 〉before APEC（ October） 〉after APEC（ December）,which indicated a decreasing order of the PM oxidative capacity of after APEC（ November） 〉before APEC（ October） 〉during APEC. The TI（ toxic index） was further introduced to represent the human exposure risk of particles,which was represented by the product of the mass concentration of PM（ μg·m- 3） and the DNA damage percentages under the PM dose of 250 μg·m L- 1（ %）. Compared with the TI values of previous years,the TI value of the 2014 APEC PM was lower than that of 2004,but higher than that of the 2008 Olypic Games,suggesting that the exposure risk of airborne particles decreased obviously with the increase of policy control strength.