Superoxide Dynamics in Irradiated Seawater

这项研究将提高对活性氧（ROS）循环如何受到海洋中光线影响的理解，这是一个研究不足的研究课题，其速率可能被低估，并对海洋表层地球化学产生影响。活性氧通过影响微量金属的可用性、细胞应激和有机化合物的性质来影响海洋中的初级生产力和碳循环。超氧化物是控制过氧化氢形成和光氧化中二氧化物（O2）命运的主要ROS。研究人员将使用一系列对照实验研究来解决有关光与暗海水中超氧化物形成的衰减速率和途径以及波长如何影响超氧化物产生的问题。该项目将支持一个早期的职业科学家，以及研究生和本科生谁将接受现场和实验室研究，光学，数据分析，光化学建模，在会议和手稿准备演示培训。研究人员将与当地高中化学教师合作，帮助他们在课堂上使用项目数据来展示环境应用和教授基本动力学。活性氧（ROS）、超氧化物（O2-）和过氧化氢（H2 O2）共同参与有机污染物的降解、有机碳循环、铁、铜和锰的氧化还原循环，这反过来又影响海洋浮游植物的分布，并有助于海洋生物主要类群的外部氧化应激。对O2-氧化还原化学中微生物作用的新认识，光学定义的光化学暴露系统的进展，以及在环境水平上用灵敏的实时化学发光同时测量O2-和H2 O2的能力，为重新研究海水中光氧化还原反应的未解问题创造了机会。本研究的目的是通过进行受控实验来捕获衰减率和途径，并没有照射和组装一个改进的，全光谱的超氧化物光化学模型，提高了在阳光照射的海洋沃茨原位ROS动态的估计，以促进了解海水中的ROS光化学。研究人员将使用各种标准和收集的溶解在人工溶液和天然海水中的有机成分的矩阵，并：1）确定，量化和限制光化学和热反应速率的范围和机制，负责在辐照期间观察到的海水中的O2-浓度; 2）量化O2-和H2 O2生产的光谱光化学效率; 3）利用基于光学的光化学模型的结果，在时间和空间尺度以及各种光学和化学限制条件下估算海水中O2和H2 O2的光化学产生率。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。

This study will improve understanding of how cycling of reactive oxygen species (ROS) is affected by light in the ocean, a research topic that has been understudied, with rates likely underestimated, and with implications for surface ocean biogeochemistry. ROS affect primary productivity and carbon cycling in the ocean by influencing availability of trace metals, cellular stress, and properties of organic compounds. Superoxide is the primary ROS controlling hydrogen peroxide formation and the fate of dioxide (O2) in photooxidation. The investigators will use a series of controlled experimental studies to address questions about decay rates and pathways of superoxide formation in light versus dark seawater and how wavelength affects superoxide production. This project will support an early career scientist, as well as graduate and undergraduate students who will receive training in field and lab research, optics, data analysis, photochemical modeling, presentations at meetings and manuscript preparation. The investigator will collaborate with local high school chemistry teachers to help them use project data in the classroom to show environmental applications and teach basic kinetics. Together, the reactive oxygen species (ROS) superoxide (O2-) and hydrogen peroxide (H2O2) are involved in the degradation of organic pollutants, organic carbon cycles, redox cycling of iron, copper, and manganese which in turn affect marine phytoplankton distributions and contribute to external oxidative stress in major taxa of marine organisms. New understanding of microbial roles in O2- redox chemistry, advances in optically defined photochemical exposure systems, and the ability to simultaneously measure both O2- and H2O2 at environmental levels with sensitive, real-time chemiluminescence create an opportunity to re-examine unanswered questions about photo-redox reactions in seawater. The objective of this study is to advance understanding of ROS photochemistry in seawater by conducting controlled experiments to capture decay rates and pathways with and without irradiation and to assemble an improved, fully spectral photochemical model for superoxide that improves estimates of in situ ROS dynamics in sunlit ocean waters. The investigators will use a matrix of various standard and collected organic constituents dissolved in constructed solutions and natural seawater and: 1) identify, quantify, and constrain the range of photochemical and thermal reaction rates and mechanisms responsible for observed O2- concentrations in seawater during irradiation; 2) quantify the spectral photochemical efficiency of O2- and H2O2 production; and 3) use results in optically-based photo-chemical models to estimate O2-and H2O2 photochemical production rates in seawater across temporal and spatial scales and various optical and chemical constraints.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.