北京市大气颗粒物化学元素组成的聚类分析

2005年9月—2006年9月期间,在北京的北郊昌平区、城区和南郊房山区3个采样点位共采集总悬浮颗粒物(TSP)样品166个。用ICP-AES和ICP-MS方法测量了Pb等29个无机元素。基于无机多元素数据的聚类分析,把166个样品分组为清洁样品和4种污染样品。清洁样品占总数的49%,以北郊清洁背景点位的样品为主;污染样品占总数的51%,主要是城区和南郊点位的样品。根据化学组成,4种污染样品分别是铝、铁、稀土等地壳元素所代表的土壤来源主导的沙尘类样品;钙、镁等元素所代表的建筑工业排放和建筑工地排放突出的建筑尘样品;硫元素所代表的燃煤等燃烧过程排放贡献突出的样品;以及铅、锌等重金属元素所代表的有色冶金工业排放突出的样品。聚类分析的结果和前期来源解析的结果是兼容一致的。如果北京市的空气质量管理和大气颗粒物污染治理工作的规划和实施综合考虑和兼顾这4类典型情况,有利于提高治理的效率和投资的效果。

Cluster Analysis of Atmospheric Aerosol in Beijing Based on Chemical Compositional Data

From September 2005 to September 2006, 166 samples of total suspended particles(TSP) were collected in Beijing at three sites in north suburb Changping, downtown, and south suburb Liangxiang, respectively. Lead and other 28 elements were measured using inductively coupled plasma-mass spectrometry(ICP-MS) and atomic emission spectroscopy(ICP-AES). Cluster analysis based on elemental compositions presented five classes as clean and polluted aerosol samples. Clean samples account for 48.8% of the total, being mainly from north suburb site; while polluted samples account for 51.2%, being largely from downtown and south suburb sites. Four classes of polluted samples had different chemical compositions, featured respectively by soil mineral dusts with high aluminium, iron and rare earth elements contents, and construction dust with high calcium and magnesium contents from manufactories and application sites, and sulphate dominating particles from coal combustion and other combustion processes, and particles with high lead and zinc contents most likely from non-ferrous industry emissions. Cluster analysis results are compatible with those of previous studies on aerosol source identification and apportionment. This kind of information is needed for Beijing air quality management and air pollution control. It will facilitate efficient air pollution control and management and effective environmental investment.