Reaction networks in environmental systems: connecting reactive oxygen species generation and particle formation during the oxidation of ferrous iron

环境系统中的反应网络：连接亚铁氧化过程中活性氧的产生和颗粒的形成

• 批准号: 1308801
• 负责人: John Ferry
• 金额: $ 40.5万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-10-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1308801&HistoricalAwards=false
• 关键词: Reaction; networks; environmental; systems; connecting

The Environmental Chemical Sciences Program in the Chemistry Division at the National Science Foundation supports the research of Professor John L. Ferry at the University South Carolina at Columbia. There have been several important works describing the oxidation of dilute (nanomolar) Fe(II) by oxygen and many describing electron transfer from ferrous/ferric solids in anoxic solutions. However, these have not been integrated into a predictive, Fe-based continuous model for estimating ROS production. In the natural environment, Fe(III) can be reduced to the Fe(II) state through photochemical processes, direct reaction with reductants (e.g. sulfides) or via microbially mediated reduction. The net cycling between the two oxidation states leads to the apparent catalytic production of ROS (which include hydroperoxyl radical and its conjugate base superoxide, hydroxyl radical and hydrogen peroxide) and provides kinetically and energetically facile connections between the elemental Fe, O, C, S and N cycles. The researchers have developed a high throughput, combinatorial approach to explore the effect of solution variation on Fe(II) oxidation and ROS yield in the presence of Fe(III). Work proposed will test the specific hypothesis that ROS production is maximized when resulting Fe(III) is sequestered in phases that can undergo atom transfer as well as electron transfer with reactants in the solution phase. ROS will be measured in the aqueous phase through the addition of a series of organic probes. The concentration of dissolved metals will be determined by a combination of spectrophotometric and mass spectrometric techniques. Solids will be characterized for 56Fe to 58Fe to O ratios using electron backscatter and mass spectrometric techniques. The exchange of isotopically labeled Fe(II) with particulate Fe will be determined using high resolution mass spectrometric techniques. These observables will be correlated to the conditional initiating matrix to develop response surfaces describing the systemic ROS generation response to oxygen addition.The outcomes of this study will result in a new understanding of how rapid Fe(II)/Fe(III) cycling is affected by co-solutes and colloids. These outcomes have significance to the general public in the context of carbon turnover driven by the by-product ROS (and hence climate change) as well as public health concerns. Results from this work will be incorporated into workshops designed to educate students and faculty outside of the field. The workshops will be developed in collaboration with the Hanse Institute for Advanced Study in Delmenhorst; Germany, and extended to the South Carolina State Museum. The proposed work will provide support for two graduate and two undergraduate students. Professors John Ferry and Tim Shaw have a well-documented record of mentoring underrepresented minorities and female students; 34 out of the 60 researchers in their laboratories have been female, and nine have been from underrepresented groups.

美国国家科学基金会化学部的环境化学科学项目支持约翰·L。渡船在哥伦比亚的南卡罗来纳州。已经有几个重要的作品描述了氧化稀（纳摩尔）Fe（II）的氧气和许多描述电子转移从亚铁/铁固体在缺氧溶液中。然而，这些还没有被整合到一个预测性的，铁为基础的连续模型，估计活性氧生产。在自然环境中，Fe（III）可以通过光化学过程、与还原剂（如硫化物）直接反应或通过微生物介导的还原为Fe（II）状态。两种氧化态之间的净循环导致ROS（包括过氧化氢自由基及其共轭碱超氧化物、羟基自由基和过氧化氢）的表观催化产生，并提供元素Fe、O、C、S和N循环之间的动力学和能量上容易的连接。研究人员开发了一种高通量的组合方法来探索溶液变化对Fe（III）存在下Fe（II）氧化和ROS产量的影响。提出的工作将测试的具体假设，即ROS的生产最大化时，产生的Fe（III）被隔离的阶段，可以进行原子转移，以及与反应物在溶液中的电子转移。通过加入一系列有机探针，在水相中测量ROS。溶解金属的浓度将通过分光光度计和质谱技术的组合来确定。将使用电子背散射和质谱技术表征固体的56 Fe至58 Fe与O的比率。将使用高分辨率质谱技术测定同位素标记的Fe（II）与颗粒Fe的交换。这些观测值将相关的条件启动矩阵开发响应面描述系统的ROS生成响应氧addition.The结果的本研究将导致一个新的理解如何快速Fe（II）/Fe（III）循环的影响，共溶质和胶体。这些结果对公众在由副产品ROS驱动的碳周转（因此气候变化）以及公共卫生问题方面具有重要意义。这项工作的结果将被纳入旨在教育学生和教师以外的领域研讨会。这些讲习班将与德国德尔门霍斯特的汉斯高级研究所合作开发，并扩展到南卡罗来纳州博物馆。拟议的工作将为两名研究生和两名本科生提供支持。约翰·费里（John Ferry）教授和蒂姆·肖（Tim Shaw）教授在指导代表性不足的少数民族和女学生方面有着良好的记录;他们实验室的60名研究人员中有34名是女性，9名来自代表性不足的群体。