Soils and vegetation as a record of anthropogenic pollutants: Mn in the Shale Hills CZO

众所周知，金属由人类活动排放到空气中，然后沉积到陆地表面。美国目前的法规要求监测空气排放；然而，过去对陆地表面的输入在很大程度上是未知的。土壤记录了进入S地表的自然和人为通量，包括大气沉积，因此可以使用质量平衡模型进行分析，以限制输入和输出。在宾夕法尼亚州立大学萨斯奎哈纳页岩山临界区天文台(CZO)开始的工作中，调查人员证明，大气输入已经污染了宾夕法尼亚州的土壤。具体地说，CZO土壤中一半以上的锰很可能是过去200年来工业来源的大气沉积增加的。对已公布的土壤数据库的调查表明，在美国和欧洲的许多工业化地区，锰污染普遍存在，但高度局部化。这些结果强调，大气输送现在是全球锰循环的一个重要组成部分。在这个项目中，研究人员正在努力了解锰是如何从大气沉积中通过土壤和植被进入溪水的。锰在影响生态系统过程中很重要，因为它具有很高的反应活性，而且它的化合物对氧化还原反应敏感。锰对光合作用和酶功能是必不可少的，但过多的锰对森林和人类也是有害的。此外，锰氧化物可以隔离大量的重金属，可以影响污染物的迁移，还可以影响土壤中的生物功能。该项目将1)量化CZO植被中的锰浓度；2)使用最先进的光谱技术检查CZO中的锰储量；3)建立土壤中锰循环的模型；4)继续挖掘和综合已发表的文献中的数据，以检验工业化地区表层土壤普遍存在锰污染的假设。这项拟议的工作将有助于在NSF资助的页岩山CZO研究风化层的合作努力，该项目已经支持了多个学科的18名学生和17名教师。该项目将支持博士生贝丝·赫恩登。研究人员还将开始与宾夕法尼亚州立大学课程与教学教授合作，改进地球科学课程，并为附近学区的K-8学生开展外联活动。

It is well known that metals are emitted to the air by human activities and subsequently deposited to the land surface. Current regulations in the U.S.A. require that air emissions be monitored; however, past inputs to the land surface are largely unknown. Soils record natural and anthropogenic fluxes to the Earth?s surface, including atmospheric deposition, and can therefore be analyzed using mass balance models to constrain inputs and outputs. In work started at the Penn State Susquehanna Shale Hills Critical Zone Observatory (CZO), the investigator has demonstrated that atmospheric inputs have contaminated soils with Mn in Pennsylvania. Specifically, over half the Mn in the soil in the CZO was most likely added by atmospheric deposition from industrial sources over the last 200 years. Investigation of published soil databases shows that Mn contamination is widespread but highly localized in many industrialized areas in the U.S.A. and Europe. These results emphasize that atmospheric transport is now a critical component of the global Mn cycle. In this project, the investigator is working to understand how Mn moves from atmospheric deposition through the soil and vegetation and into stream water. Mn is important in impacting ecosystem processes because of its high reactivity and because its compounds are redox-sensitive. Mn is essential for photosynthesis and enzymatic function but can also be toxic to forests and humans in high amounts. Additionally, Mn-oxides can sequester large concentrations of heavy metals, can affect mobility of contaminants, and can impact biotic function in soils. This project will 1) quantify concentrations of Mn in CZO vegetation; 2) examine the reservoirs of Mn in the CZO using state-of-the-art spectroscopic techniques; 3) develop models of Mn cycling in the soils; and 4) continue to mine and synthesize data from published literature to test the hypothesis of widespread Mn contamination of topsoils in industrialized regions. The proposed work will contribute to collaborative efforts to study regolith weathering at the NSF-funded Shale Hills CZO, which has supported 18 students and 17 faculty across multiple disciplines. The project will support doctoral student Beth Herndon. The researchers will also begin to collaborate with a Pennsylvania State University professor of Curriculum and Instruction to improve the Earth science curriculum and develop outreach activities for K-8 students in a nearby school district.