Trends in hazardous trace metal concentrations in aerosols collected in Beijing, China from 2001 to 2006
Trends in hazardous trace metal concentrations in aerosols collected in Beijing, China from 2001 to 2006
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DOI：
10.1016/j.chemosphere.2008.03.033
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发表时间：
2008-06-01
期刊：
影响因子：
8.8
通讯作者：
Jia, Yingtao
中科院分区：
文献类型：
--
作者：
Okuda, Tomoaki;Katsuno, Masayuki;Jia, Yingtao
对2001 ~ 2006年北京地区气溶胶中有害微量金属的浓度进行了逐日观测。通过相关性分析和对金属富集因素和相对组成的研究，我们认为煤燃烧是一些人为金属的主要来源。某些特定金属（如Cu和Sb）的可能额外来源是刹车磨损颗粒，然而，我们认为与运输相关的颗粒不是有害人为金属的主要来源，即使它们可能来自汽车尾气和刹车/轮胎磨损颗粒。采用时间趋势模型来描述五年期间化学成分浓度的时间变化。Al、Ti、V、Cr、Mn、Fe、Co等地壳元素的年增率在-15.2% ~ 3.6%之间，没有明显的增加。另一方面，几种有害微量金属的含量呈严重上升趋势。根据回归模型，Cu、Zn、As、Cd和Pb主要来源于煤炭燃烧等人为来源，其年变化速率较高（4.9 ~ 19.8%,p < 0.001）。特别是Cd和Pb浓度显著升高。我们假设，空气中金属浓度增加的趋势反映了煤炭燃烧过程中发生的变化，即使用更高的温度进行煤炭燃烧导致这些金属的排放量增加。低等级煤使用的增加也可以解释观察到的趋势。此外，有色金属冶炼厂被认为是北京市大气中人为有害金属浓度增加的一个潜在原因，尽管是次要原因。(C) 2008 Elsevier Ltd版权所有。
Daily observations of hazardous trace metal concentrations in aerosols in Beijing, China were made in the period from 2001 to 2006. We considered coal combustion as a major source of some anthropogenic metals by achieving a correlation analysis and by investigating enrichment factors and relative composition of metals. A possible extra source of some specific metals, such as Cu and Sb, was brake abrasion particles, however, we did not think the transport-related particle was a major source for the hazardous anthropogenic metals even though they could originate from vehicle exhaust and brake/tire abrasion particles. A time-trend model was used to describe temporal variations of chemical constituent concentrations during the five-year period. Several crustal elements, such as Al, Ti, V, Cr, Mn, Fe, and Co, did not show clear increases, with annual rates of change of -15.2% to 3.6%. On the other hand, serious increasing trends were noted from several hazardous trace metals. Cu, Zn, As, Cd, and Pb, which are derived mainly from anthropogenic sources, such as coal combustion, showed higher annual rate of change (4.9-19.8%, p < 0.001) according to the regression model. In particular, the Cd and Pb concentrations increased remarkably. We hypothesize that the trend towards increasing concentrations of metals in the air reflects a change that has occurred in the process of burning coal, whereby the use of higher temperatures for coal combustion has resulted in increased emissions of these metals. The increasing use of low-rank coal may also explain the observed trends. In addition, nonferrous metal smelters are considered as a potential, albeit minor, reason for the increasing atmospheric concentrations of anthropogenic hazardous metals in Beijing city. (C) 2008 Elsevier Ltd. All rights reserved.