Department of Geology, Kansas State University, Manhattan, Kansas 66506, United States.
Environ Sci Technol. 2012 Mar 20;46(6):3101-9. doi: 10.1021/es203435n. Epub 2012 Mar 1.
The purpose of this study is to characterize manganese oxidation states and speciation in airborne particulate matter (PM) and describe how these potentially important determinants of PM toxicity vary by location. Ambient PM samples were collected from five counties across the US using a high volume sequential cyclone system that collects PM in dry bulk form segregated into "coarse" and "fine" size fractions. The fine fraction was analyzed for this study. Analyses included total Mn using ICP-MS and characterization of oxidation states and speciation using X-ray absorption spectroscopy (XAS). XAS spectra of all samples and ten standard compounds of Mn were obtained at the National Synchrotron Light Source. XAS data was analyzed using Linear Combination Fitting (LCF). Results of the LCF analysis describe differences in composition between samples. Mn(II) acetate and Mn(II) oxide are present in all samples, while Mn(II) carbonate and Mn(IV) oxide are absent. To the best of our knowledge, this is the first paper to characterize Mn composition of ambient PM and examine differences between urban sites in the US. Differences in oxidation state and composition indicate regional variations in sources and atmospheric chemistry that may help explain differences in health effects identified in epidemiological studies.
本研究的目的是描述大气颗粒物（PM）中锰的氧化态和形态特征，并描述这些可能对 PM 毒性有重要影响的因素如何因地点而异。使用大容量顺序旋风系统从美国五个县采集环境 PM 样本，该系统以干燥块状形式收集 PM，并分为“粗”和“细”粒径。本研究对细颗粒进行了分析。分析包括使用 ICP-MS 进行总 Mn 分析以及使用 X 射线吸收光谱（XAS）进行氧化态和形态特征分析。在国家同步辐射光源处获得了所有样品和十种 Mn 标准化合物的 XAS 光谱。使用线性组合拟合（LCF）对 XAS 数据进行了分析。LCF 分析结果描述了样品之间成分的差异。所有样品中均存在乙酸锰(II)和氧化锰(II)，而碳酸锰(II)和氧化锰(IV)则不存在。据我们所知，这是第一篇描述环境 PM 中 Mn 组成并研究美国城市地区之间差异的论文。氧化态和组成的差异表明，来源和大气化学存在区域性变化，这可能有助于解释在流行病学研究中发现的健康影响差异。
