DeYoung Jessica L, Akporere Uchechukwu Grace, Cheng Zezhen, China Swarup, Vandergrift Gregory W, Anderton Christopher R, Zhou Yadong, Zhu Zihua, Shaw Scott K
University of Iowa, Iowa City, Iowa state 52242, United States.
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
ACS Earth Space Chem. 2024 Nov 14;8(12):2411-2419. doi: 10.1021/acsearthspacechem.4c00170. eCollection 2024 Dec 19.
Environmental films form when airborne particles and molecular species adsorb on solid surfaces. Recent studies have characterized these films but overlook how collection methods and host-surface character (orientation, chemical functionality, or height) change the deposition process. In this work, environmental films are collected at a rural location on gold and silicon surfaces (water contact angles of ca. 57° and <1°, respectively) to determine how the different substrate changes the properties of the accumulated environmental film. Results show that gold surfaces have a homogeneous distribution of film mass across the surface, while silicon surfaces collect films with irregular patchy domains. The two surfaces also develop different surface coverages and particle number densities, and the particles' packing arrangements are quantified by analyzing nearest-neighbor distances. Computer-controlled scanning electron microscopy with energy-dispersive X-ray spectroscopy suggests that, despite morphological differences, larger (>5 μm) particles have similar elemental compositions. Minor variations are observed at smaller particle sizes (∼5 μm), which include carbon-rich particles primarily attributed to pollen or biotic activity. Chemical analysis shows the presence of nitrate and sulfate, as well as heterogeneous cation pools on the surfaces.
当空气中的颗粒和分子物种吸附在固体表面时，环境薄膜就会形成。最近的研究已经对这些薄膜进行了表征，但忽略了收集方法和宿主表面特性（取向、化学官能团或高度）如何改变沉积过程。在这项工作中，在农村地区的金和硅表面（水接触角分别约为57°和<1°）收集环境薄膜，以确定不同的基底如何改变累积的环境薄膜的性质。结果表明，金表面的薄膜质量在整个表面上分布均匀，而硅表面收集的薄膜具有不规则的斑块状区域。这两个表面还形成了不同的表面覆盖率和颗粒数密度，并且通过分析最近邻距离来量化颗粒的堆积排列。带有能量色散X射线光谱的计算机控制扫描电子显微镜表明，尽管形态不同，但较大（>5μm）的颗粒具有相似的元素组成。在较小的颗粒尺寸（约5μm）处观察到微小变化，其中包括主要归因于花粉或生物活动的富碳颗粒。化学分析表明表面存在硝酸盐和硫酸盐以及异质阳离子池。
