Unisense MicroProfiling System for High-Resolution Aqueous Geochemical Measurements

所要求的设备是Unisense公司的自动微谱分析系统（MPS），将允许在微米空间分辨率下对水、沉积物、土壤和生物膜中的氧、氮、硫化物、氢、氧化还原和pH进行化学测量。以下是需要MPS的研究课题：(1)确定现代微生物过程如何影响沉积物（如页岩）的微量金属组成。MPS将测量现代海岸沉积物的原位生物地球化学分带，并结合孔隙水和沉积物地球化学分析，揭示在埋藏过程中微量金属模式的改变。反过来，这对于评估古页岩的组成是否可以用来推断古海水的组成很重要。(2)确定生物炭（热解碳）对全球元素循环、土壤化学和氧化还原性质以及污染物运输的影响。在氧化还原条件变化迅速的土壤上部，需要MPS来测量颗粒尺度上的氧化还原变化和微生物呼吸，以及旨在模拟受控环境下生物炭迁移的实验室柱实验。(3)通过水族箱研究，确定海水中溶解氧降低对海底沉积物中动物大小和多样性的影响，在水族箱中，在受控条件下饲养沉积物栖息群落。MPS可以观察动物种群的大小和多样性对氧气降低和硫化物上升的反应，这些反应可以用来解释岩石记录中的痕量化石数据。(4)研究构成生命的元素（如碳、氮、硫）和关键金属（如铁）的循环及其对深层地下水和温泉宜居性的影响。MPS允许在高空间分辨率下对氧化还原条件进行原位测量，特别是在这种环境中缺乏数据的氮物种。(5)研究微生物形成矿物的机制及其对矿物相变的影响。MPS将使收集环境和实验室水族箱中沉积物-水界面的pH值、氧化还原条件和微量气体浓度剖面成为可能。这些数据将与电子和同步加速器显微镜相结合，在微米尺度上提供前所未有的生物矿化图像。(6)表征加拿大北极冰川融水中的营养物质如何影响海洋微生物群落。MPS将通过确定底层沉积物的生物地球化学分带来扩展这些研究，从而阐明生物量及其同化的营养物质是如何被处理的。这种水和沉积物柱数据集的配对将显示生物质如何保存在现代沉积物中，并最终了解地球历史上过去广泛的冰川时期（例如“雪球地球”）对海洋浮游植物进化的影响。

The equipment requested, an automated MicroProfiling System (MPS) from Unisense, will allow for chemical measurements of oxygen, nitrogen species, sulfide, hydrogen, redox and pH at micrometer spatial resolution in water, sediments, soils, and biofilms. The following are research topics that require the MPS: (1) Determining how modern microbial processes impact the trace metal composition of sediments, such as shales. The MPS will measure the in situ biogeochemical zonation in modern coastal sediment, which combined with the analyses of porewater and sediment geochemistry, shows how trace metal patterns are modified during burial. This is, in turn, important for assessing whether the composition of ancient shales can be used to infer paleo-seawater composition. (2) Ascertaining the influence of biochar (pyrolyzed carbon) on global elemental cycling, soil chemistry and redox properties, and contaminant transport. The MPS is needed to measure redox changes and microbial respiration at the grain scale in the upper part of soils where redox conditions change rapidly, and in laboratory column experiments that aim to simulate biochar migration in a controlled environment. (3) Establishing the influence of lowered dissolved oxygen in marine waters on animal size and diversity in seafloor sediments through aquaria studies where sediment-dwelling communities are held under controlled conditions. The MPS allows an observation of animal-population size and diversity responses to lowered oxygen and rising sulfide that can be used to interpret trace fossil data in the rock record. (4) Examining the cycles of life-constituting elements (e.g., carbon, nitrogen, sulfur) and critical metals (e.g., iron) and their impacts on the habitability in deep subsurface groundwaters and hot springs. The MPS allows for in situ measurements of redox conditions at a high spatial resolution, specifically nitrogen species for which there is a dearth of data in such environments. (5) Studying the mechanisms by which microbes form minerals and how they influence mineral phase transitions. The MPS will make it possible to collect profiles of pH, redox conditions, and trace gas concentrations at the sediment-water interface in both the environment and laboratory aquaria. This data will be combined with electron and synchrotron microscopy to provide an unprecedented picture of biomineralization at the micron scale. (6) Characterizing how nutrients in glacial meltwaters of the Canadian Arctic impact marine microbial communities. The MPS will extend these studies by determining the biogeochemical zonation of underlying sediments, thus elucidating how biomass and their assimilated nutrients are processed. This pairing of water and sediment column datasets will show how biomass is preserved in modern sediment, and ultimately to understand the effects of past periods of extensive glaciation in Earth's history (e.g., `Snowball Earth') on the evolution of marine phytoplankton.