Speciation of elements in NIST particulate matter SRMs 1648 and 1650
Speciation of elements in NIST particulate matter SRMs 1648 and 1650
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DOI：
10.1016/s0304-3894(99)00195-8
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发表时间：
2000-05-29
影响因子：
13.6
通讯作者：
Robertson, JD
中科院分区：
文献类型：
--
作者：
Huggins, FE;Huffman, GP;Robertson, JD
对美国国家标准与技术研究所（NIST）的两种颗粒物（PM）标准参考物质：城市PM （SRM 1648）和柴油PM (SRM 1650)，分别获得了S、Cl、V、Cr、Mn、Cu、Zn、As、Br、Cd和Pb的x射线吸收精细结构（XAFS）光谱和Fe的穆斯堡尔光谱。光谱数据，加上质子诱导x射线发射（PIXE）光谱的元素浓度信息，被用来解释这些复杂材料中这些元素的形态。似乎所有被调查的金属元素都以氧化形式出现，主要是柴油PM SRM中的硫酸盐，以及城市PM中的硫酸盐，氧化物和可能的其他形式（例如粘土？）。硫的一小部分和卤素的主要部分Cl和Pr分别以有机硫化物（噻吩）和有机卤化物的形式出现，这必然与构成两种PM SRMs的主要成分的丰富的碳质物质有关。然而，大多数硫在城市PM中以硫酸盐形式存在，在柴油PM中以硫酸氢盐形式存在。此外，元素的氧化态也可以用光谱技术直接测定。这些信息往往是确定PM中特定元素的毒性和溶解度的关键参数，这两者对于了解这些元素可能对人类健康构成的威胁都很重要。对于毒性很大程度上取决于氧化态的两种HAP元素Cr和As， XAFS数据表明，这两种元素主要以毒性较小的氧化态Cr（III）和As(V)存在于两种SRMs中。通过参考铬，可以看出XAFS光谱作为源分配特征的潜力，铬在这两种PM SRMs中以非常不同的形式存在。(C) 2000 Elsevier Science B.V.版权所有
X-ray absorption fine structure (XAFS) spectra for S, Cl, V, Cr, Mn, Cu, Zn, As, Br, Cd and Pb and Mossbauer spectra for Fe have been obtained for two National Institute of Standards and Technology (NIST) particulate matter (PM) standard reference materials (SRMs): urban PM (SRM 1648) and diesel PM (SRM 1650). The spectral data, complemented by information on elemental concentrations from proton-induced X-ray-emission (PIXE) spectroscopy, were used to interpret the speciation of these elements in these complex materials. It appears that all the metallic elements investigated occur in oxidized forms, principally as sulfates in the diesel PM SRM and as sulfates, oxides, and possibly other forms (e.g. clays?) in the urban PM. A minor fraction of the sulfur and major fractions of the halogens, Cl and Pr, occur as organosulfide (thiophene) and organohalide occurrences, respectively, that must be associated with the abundant carbonaceous matter that constitutes the major component of the two PM SRMs. Most of the sulfur, however, occurs as sulfate in the urban PM and as bisulfate in the diesel PM. In addition, elemental oxidation states have been determined directly by the spectroscopic techniques. Such information is often the key parameter in determining the toxicity and solubility of specific elements in PM, both of which are important in understanding the threat that such elements may pose to human health. For the two HAP elements, Cr and As, for which the toxicity depends greatly on oxidation state, the XAFS data showed that both elements are present in both SRMs predominantly in the less toxic oxidation states, Cr(III) and As(V). The potential of the XAFS spectra for use as source apportionment signatures is illustrated by reference to chromium, which exists in these two PM SRMs in very different forms. (C) 2000 Elsevier Science B.V. All rights reserved.