中文摘要：

为了研究北京大气降尘中重金属污染水平及其空间变异特征,分别于2013年6—10月（非采暖期）、2013年11月—2014年3月（采暖期）收集了北京大气降尘样品66份,采用Elan DRCⅡ型电感耦合等离子体质谱仪（ICP-MS）测试了样品中的37种重金属质量分数.结果表明：非采暖期北京大气降尘中Cd、Zn、Pb 3种重金属污染最严重,三者质量分数分别为5.3、822.0、177.2mg/kg,分别超出各自北京背景值的1 065.0%、516.2%和403.1%;采暖期北京大气降尘中Mo、Cd、Bi、Zn 4种重金属污染最严重,四者质量分数分别为8.7、2.7、3.0、660.5 mg/kg,分别超出各自北京背景值的656.9%、495.8%、457.5%和395.2%;与非采暖期相比,采暖期大气降尘重金属中除Zn、Pb、Cd质量分数分别降低了19.6%、25.3%和48.9%外,其余元素的质量分数却有不同程度的升高,其中Sr、Ba、Ce、Cu、Cr、W、La、Ni、Mo、Co等10种重金属质量分数升高了53.2%~176.7%.Arc GIS地统计插值研究表明,非采暖期主要重金属（Cr、Cu、Zn、Zr、Ba和Pb）空间分布呈现出较强的变异性;采暖期降尘中主要重金属存在不同程度的空间变异,Ba和Zn的空间变异较强,二者高值区和低值区相互交错分布;Cu和Pb的空间变异相对较弱,二者高值区和低值区分布均呈规律性分布.元素示踪分析表明,无论是采暖期还是非采暖期,北京降尘重金属污染均主要来源于机动车尾气和垃圾焚烧.

英文摘要：

In order to study the pollution levels and spatial variation characteristics of heavy metals in atmospheric deposition in Beijing,66 deposition samples were collected in Beijing during June 2013 to October 2013（ non-heating period） and November 2013 to March2014（ heating period）. Subsequently,37 heavy metals（ mass percentage） were measured by Elan DRC Ⅱ-type inductively coupled plasma mass（ ICP-MS）. The results showed that the pollution of Cd（ 5. 3 mg/kg）,Zn（ 822. 0 mg/kg） and Pb（ 177. 2 mg/kg） in atmospheric deposition in Beijing in the non-heating period was serious,with concentrations 1065. 0%,516. 2% and 403. 1% more,respectively,than those of corresponding heavy metals in the surface soil during the same period. Mo（ 8. 7 mg/kg）,Cd（ 2. 7 mg/kg）,Bi（ 3. 0 mg/kg） and Zn（ 660. 5 mg/kg） in the heating period were seriously contaminated,with concentrations 656. 9%,495. 8%,457. 5% and 395. 2% more, respectively, than those in the surface soil. Compared with those in the non-heating period, the concentrations of every element except Zn,Pb and Cd（ reduced by 19. 6%,25. 3% and 48. 9% respectively） in atmospheric deposition in the heating period were elevated by various degrees.There were 10 elements,including Sr,Ba,Ce,Cu,Cr,W,La,Ni,Sc,Mo and Co,whose concentrations increased by 53. 2%-176. 7%. Both variation coefficient study and Arc GIS geostatistical interpolation study found that the concentrations of main heavy metals（ Cr, Cu, Zn, Zr,Ba and Pb） showed greatvariation between different sampling points in the non-heating period,with spatial distribution presenting strong variability. In the heating period,the main heavy metals in the deposition showed different degrees of spatial variation. Spatial variations of Ba and Zn were strong,with the high value regions and low value regions mutually crisscrossing. On the contrary,those of Cu and Pb were relative weak,with the high value regions and low value regions distributed regularly. Tracer element analysis showed tha