Deployable in Situ Electrochemical Analyzer (ISEA) for Remote and Automatic Analysis of O2, H2S and Sulfur Species in Hydrothermal Vent Environments

P.I. Luther 0136671本项目拟购买一台原位电化学分析仪（ISEA），该分析仪可部署在任何海洋深度的着陆器，系泊和CTD型剖面仪上，用于水域和孔隙水域的远程水生实验。使用该仪器，在一次电位扫描期间，许多氧化还原物质可以在金汞合金固态电极上通过伏安法同时测定。这些物质包括溶解氧、硫化物、硫代硫酸盐、多硫化物、碘化物、Fe（II）、Mn（II）和FeS。氧和总溶解硫化物的测量精度和灵敏度都很高。测量不需要化学操作，最多四个工作电极可以安装在不同的深度和位置，以获取水柱中的化学信息。该分析仪是监测重要氧化还原机制的理想选择，如在近岸和陆架环境中季节性缺氧的发展，热液喷口硫化学的变化以及沉积物中氧化还原物种的概况，停滞的海湾，河口和盆地。在之前提交的报告中，这些研究领域的目标是进行测量，但审稿人指出，这太过雄心勃勃，只应该选择一个领域进行进一步的工作。本文的研究重点是热液喷口研究。事件中的一个主要问题是；喷口和扩散流化学的变化会影响生物体在不同地点的定居方式？最近的研究表明，不同的生物有机体生活在不同的化学生态位中。因此，能够测量各种氧化还原物种的原位传感器将是提高我们对这些环境中水化学在时间和空间尺度上的生物地球化学研究的理解的理想选择。原位电化学分析仪的原型已经成功地用于DSV Alvin，现在可以从分析仪器系统公司买到。该系统被设计为使用DSV Alvin的直流电源，电极部署在给定的通风口位置，由潜水器中的操作员控制。该技术发展的下一步是向系统添加远程或自动功能，以监视各种系统中的时间变化。虽然ISEA是一个单一的系统，但它将有四个Au/Hg工作电极，每个工作电极上集成了四个温度和pH传感器。本质上，ISEA是一个分析仪中用于伏安法，温度和pH值的四个独立仪器包，允许分析四个单独的位置/深度。作为该提案的一部分，将对金汞合金（Au/Hg）电极进行长期部署测试。测试将包括在特拉华大学港口的河口水域和热液喷口水域进行长期部署。

P.I. Luther 0136671This project proposes to purchase an in situ electrochemical analyzer (ISEA) that can be deployed at any ocean depth on landers, moorings and CTD type profilers for remote aquatic experiments in waters and porewaters. With this instrument, many redox species can be determined simultaneously by voltammetry at a gold-amalgam solid-state electrode during one potential scan. These species include dissolved oxygen, sulfide, thiosulfate, polysulfides, iodide, Fe(II), Mn(II), and FeS. Oxygen can be measured with high precision and sensitivity as can total dissolved sulfide. No chemical manipulations are necessary for measurement and up to four working electrodes can be mounted at different depths and locations to obtain chemical information in the water column. This analyzer is ideal for monitoring important redox regimes such as the development of seasonal anoxia in nearshore and shelf environments, the changes in sulfur chemistry at hydrothermal vents and the profiles of redox species in sediments, stagnant bays, estuaries and basins. In a previous submission, these areas of study were targeted for making measurements but the reviewers indicated that this was too ambitious and only one should be selected for further work. In this proposal, the focus is on hydrothermal vent research. A major concern at vents is; what are the changes in vent and diffuse flow chemistry that affect the way organisms colonize different sites? Recent work has shown that different biological organisms reside in different chemical niches. Thus, in situ sensors that can measure a variety of redox species would be ideal for improving our understanding of biogeochemical studies of water chemistry on temporal and spatial scales in these environments.A prototype in situ electrochemical analyzer has been successfully used on the DSV Alvin and is now commercially available from Analytical Instrument Systems, Inc. This system was designed to use DC power from DSV Alvin with electrodes deployed at given vent locations by the submarine's manipulators controlled by an operator in the submersible. The next step in development of this technology is to add remote or automatic capability to the system to monitor temporal changes in a variety of systems. Although the ISEA is a single system, it will have four Au/Hg working electrodes with four temperature and pH sensors integrated with each of the working electrodes. In essence, the ISEA is four separate instrument packages for voltammetry, temperature and pH in one analyzer, which permits analysis of four separate locations/depths. As part of this proposal the gold-amalgam (Au/Hg) electrodes will be tested for long-term deployment. The testing will include long-term deployment in estuarine waters at the University of Delaware's harbor and at hydrothermal vent waters.