Molecular Insights into the Oxidation of Atmospheric Mercury

在这个由美国国家科学基金会化学部环境化学科学计划资助的项目中，纽约州立大学环境科学与林业学院的西奥多·迪布尔教授和密西西比州立大学的王楚基博士正在研究汞原子如何在大气中反应，形成易于转移到生态系统中的分子。 汞在大气中的反应并不为人所知。 汞在何处、何时进入生态系统，以及如何在地球仪中迁移，这些问题特别令人感兴趣。汞对人类和野生动物有毒。汞在大气中的浓度并不有害，但一旦汞进入生态系统，它就会在动物组织中集中到被其他动物或人类食用时危险的水平。Dibble博士与高中教师合作，开发基于含汞化学的动力学教学模块。这项工作的更广泛影响包括首次通过实验测定含汞分子在大气中反应的产物，以及将这项研究的结果纳入汞化学和沉积的大气模型。腔衰荡光谱（CRDS）用于监测HgBr自由基与大气微量气体反应的结果。CRDS实验和计算化学首次用于确定HgBr自由基与臭氧、挥发性有机化合物（VOCs）和大气中丰富的自由基（Y.自由基，其中Y. = NO、NO2、HOO、ClO、BrO和IO）。速率常数被确定为温度和压力的函数，以跨越整个大气条件范围。进行实地研究、建模和实验室工作的科学家之间的协同互动加速了对全球汞循环的理解。

In this project, funded by the Environmental Chemical Sciences Program in the Chemistry Division at the National Science Foundation, Professor Theodore Dibble at the State University of New York (SUNY) College of Environmental Science and Forestry and Dr. Chuji Wang of Mississippi State University are investigating how atoms of mercury react in the atmosphere to form molecules that are readily transferred into ecosystems. Atmospheric reactions of mercury are not well known. Questions of where and when mercury enters ecosystems and how it is transported around the globe are of special interest. Mercury is toxic to people and wildlife. Mercury in the atmosphere is not present in harmful concentrations, but once mercury enters ecosystems it is concentrated in animal tissues to levels that are dangerous when eaten by other animals or humans. Dr. Dibble works with high school teachers to develop modules to teach kinetics based on mercury-containing chemistry. The broader impacts of this work include the first experimental determination of the products of atmospheric reactions of mercury-containing molecules, and the incorporation of the results of this research into atmospheric models of mercury chemistry and deposition.This project focuses on mercury oxidation by atomic bromine (Br). Cavity ringdown spectroscopy (CRDS) is used to monitor the fate of the HgBr radical in reactions with atmospheric trace gases. CRDS experiments and computational chemistry are used to determine, for the first time, the rate constants for reactions of HgBr radicals with ozone, volatile organic compounds (VOCs), and atmospherically abundant radicals (Y. radicals, where Y. = NO, NO2, HOO, ClO, BrO, and IO). Rate constants are determined as a function of temperature and pressure to span the full range of atmospheric conditions. Synergistic interactions between scientists doing field studies, modeling, and laboratory work accelerate progress towards understanding global mercury cycling.