Polycyclic aromatic hydrocarbons in urban air particulate matter:: Decadal and seasonal trends, chemical degradation, and sampling artifacts
Polycyclic aromatic hydrocarbons in urban air particulate matter:: Decadal and seasonal trends, chemical degradation, and sampling artifacts
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DOI：
10.1021/es034059s
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发表时间：
2003-07-01
影响因子：
11.4
通讯作者：
Pöschl, U
中科院分区：
文献类型：
--
作者：
Schauer, C;Niessner, R;Pöschl, U
在一个主要的城市交通路口（LKP）和郊区住宅区（IWC）在大都市地区的慕尼黑（德国）在整个2001年和2002年收集的气溶胶过滤器样品进行了分析的12个EPA优先多环芳烃（PAH）污染物的液相色谱荧光检测。在LKP采样的空气中，所有调查的PAH总和的平均质量浓度（1.9-5.0 ng m（-3））大约是IWC（0.8-2.9 ng m（-3））的两倍，在这两个地点，冬季（供暖季节）比夏季和春季或秋季高出约2-3倍。与早期测量活动的比较表明，从1980年到1993年，多环芳烃丰度急剧下降了近一个数量级，此后下降速度要慢得多。对于半挥发性的3环和4环多环芳烃以及颗粒结合的5环和6环多环芳烃，观察到了明显不同的季节趋势和短期波动。基于系统的相关性分析与广泛的空气质量参数，大部分的差异可以归因于不仅不同的排放量，但也与大气氧化剂的化学反应，发现发挥重要作用。扩散管实验的结果证明，特别有毒的示踪剂苯并[a]芘和其他研究的5-和6-环多环芳烃的大量降解可以发生在过滤器采样和空气中的颗粒（形成氧化和硝化衍生物）。过滤器反应文物显示，导致低估的实际PAH含量的城市空气颗粒物的测量值的100%或更多，与臭氧体积混合比的近线性依赖。臭氧的作用和适用性作为示踪剂的大气氧化能力的颗粒结合的多环芳烃进行了讨论和确认，通过比较与早期的调查和补充实验室实验（反应动力学和产品的研究）。
Aerosol filter samples collected at a major urban traffic junction (LKP) and at a suburban residential location (IWC) in the metropolitan area of Munich (Germany) throughout the years 2001 and 2002 have been analyzed for 12 of the 16 EPA priority polycyclic aromatic hydrocarbon (PAH) pollutants by liquid chromatography with fluorescence detection. The mean mass concentration of the sum of all investigated PAH in the sampled air at LKP (1.9-5.0 ng m(-3)) was roughly two times higher than at IWC (0.8-2.9 ng m(-3)), and at both locations it was about 2-3 times higher in winter (heating season) than in summer and spring or autumn. Comparisons with earlier measurement campaigns indicate a steep decrease of PAH abundance by almost an order of magnitude from 1980 to 1993 and a much slower decrease since then. Distinctly different seasonal trends and short-term fluctuations have been observed for semivolatile 3- and 4-ring PAH and for particle-bound 5-and 6-ring PAH. Based on systematic correlation analyses with a wide range of air quality parameters, most of the differences can be attributed to not only varying emissions but also chemical reactions with atmospheric oxidants which were found to play an important role. The results of denuder experiments prove that substantial degradation of the particularly toxic tracer benzo[a]pyrene and of the other investigated 5- and 6-ring PAH can occur during filter sampling and on airborne particles (formation of oxygenated and nitrated derivatives). Filter reaction artifacts are shown to lead to an underestimation of the actual PAH content of urban air particulate matter by up to 100% of the measurement value or more, with a near-linear dependence on ozone volume mixing ratio. The role and applicability of ozone as a tracer of atmospheric oxidizing capacity for particle-bound PAH is discussed and confirmed by comparison with earlier investigations and by complementary laboratory experiments (reaction kinetics and product studies).