北京大气铅污染的变化规律研究

Changing properties of atmospheric lead pollution in Beijing

分析了1985-2009年北京大气铅污染变化过程.结果表明：北京市区大气铅浓度存在准10a的变化周期,20世纪80年代中期以来,车公庄站大气铅浓度每10a左右出现一个下降-上升过程;古城与车公庄变化规律较为一致,但受首钢局地源排放影响明显,20世纪90年代,铅浓度上升过程中升幅较大,而下降过程迟缓.受区域污染排放总量增加影响,20多年来北京大气铅的背景浓度以升高为主,与市区差距在逐渐缩小.20世纪80年代后期,大气污染的集中整治使北京大气铅浓度明显降低,但在1990年亚运会之后出现了反弹.20世纪90年代后期,汽油无铅化进程极大地缓解了大气铅污染的加重趋势,但2000-2009年前期,其环境效益很快为煤炭燃烧和建筑源贡献的快速增加所抵消,大气铅浓度经过短暂降低后再次回升.与2007年相比,2008年奥运期间北京大气铅浓度明显降低,但其在重金属中的比重却有所升高.奥运会后大气铅浓度维持在较低水平,可能源于控制措施的持续作用及区域产业结构调整.

Aerosol lead data during 1985-2009 were thoroughly analyzed with aim to reveal the changing properties of the atmospheric lead pollution in Beijing.There was a 10a quasi-cycle variation in the changes of the aerosol lead concentration in Beijing.The aerosol lead concentration at Chegongzhuang station was in upward/downward tendency per approximately 10 a.Greatly influenced by steel melting,the aerosol lead concentration at Gucheng station increased quickly but decreased slowly during 1990＇s.Under the impacts of the increased regional air pollution emissions,the background aerosol lead concentration in recent 20 years was dominated by increase in Beijing,and the difference of lead concentration between background and city was greatly reduced.The phase-out of leaded gasoline in the late 1990＇s decreased the aerosol lead level significantly,but its effect was counteracted by the strong increase of other lead sources.Later air cleaning measures taken during 2008 Beijing Olympic Games reduced lead emissions,however lead＇s ratio to other heavy metal was rising.The lead concentrations remained low after,possibly derived from Olympic source control efforts,a down turn in the economy and the adjustment of industrial structure.