Photochemical Reactions of Particulate Mercury Species at the Water-Particle Interface in Aquatic Environments

在这个项目中，佛罗里达国际大学的蔡勇、刘光良和凯文·奥谢博士得到了美国国家科学基金会化学部环境化学科学项目的资助，研究汞（Hg）与水生环境中颗粒物的反应。这些微粒汞（pHg）在自然沃茨中非常常见，通常被认为是不活泼的，移动的不多。然而，它们确实会在阳光的影响下发生反应（光化学反应），因此，要准确描述汞的循环，特别是汞的空气-水交换，就必须考虑到它们。该项目旨在提供对这些光化学反应的基本了解，并探索pHg在空气-水汞交换中的作用。该项目有一个广泛的利益，研究，教育和推广在西班牙裔服务机构。它为博士和本科生提供培训。少数民族学生获得研究经验。独特的以环境化学为重点的博士轨道计划的课程开发正在加强。该项目还提高了公众对汞污染和健康风险的认识。由于水生颗粒是半导体和光敏性的性质，研究人员集中在pHg涉及电子空穴对和活性氧的光化学反应。他们定义的pHg光转化的反应途径和量化的动力学的光化学还原的氧化汞物种和元素pHg的氧化。他们还研究了与pHg光反应相关的机制。使用模型铁，钛，锰氧化物粒子的不同带隙能量和场收集粒子的实验与量子化学计算相结合。带隙能量分析使用光谱测量。使用电感耦合等离子体质谱（ICP-MS）和扫描电子显微镜（SEM）测定颗粒的化学组成和光学性质。溶解态和颗粒态元素汞和氧化态汞的分析基于同位素稀释、吹扫和捕集、热解吸和ICP-MS方法。该研究有望阐明汞的光化学转化过程中pHg物种的参与以及在空气-水汞交换中的作用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project, Drs. Yong Cai, Guangliang Liu, and Kevin O'Shea at the Florida International University are funded by the Environmental Chemical Sciences Program of the NSF Division of Chemistry to study the reactions of mercury (Hg) that is associated with particles in aquatic environments. These particulate Hg species (pHg) are very common in natural waters, and they are often thought of as unreactive and not very mobile. However, they do react under the influence of sunlight (photochemical reactions) and need to be considered for an accurate description of Hg cycling, especially the air-water exchange of Hg. This project aims to provide a basic understanding of these photochemical reactions and explore the role of pHg in the air-water Hg exchange. The project has a broad range of benefits to research, education, and outreach at a Hispanic Serving Institution. It provides training for PhD and undergraduate students. Underrepresented minority students gain research experience. The curriculum development of the unique Environmental Chemistry-focused PhD track program is being enhanced. The project also promotes public awareness on Hg contamination and health risks. Since the aquatic particles are semiconducting and photosensitizing in nature, the investigators focus on the photochemical reactions of pHg involving electron-hole pairs and reactive oxygen species. They define the reaction pathways of pHg phototransformations and quantify the kinetics of photochemical reduction of oxidized Hg species and the oxidation of elemental pHg. They also study the mechanisms related to the pHg photoreactions. Experiments using model iron, titanium, and manganese oxide particles of different band gap energies and field-collected particles are combined with quantum chemistry calculations. The bandgap energies analysis uses spectrometric measurements. Particle chemical composition and optical properties are determined using inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy (SEM). The analysis of elemental and oxidized Hg in the dissolved and particulate phases is based on an isotope dilution, purge and trap, thermal desorption, and ICP-MS method. The research is expected to clarify the involvement of pHg species in Hg photochemical transformation and the role in air-water Hg exchange.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.