Development of an oceanic in situ carbon dioxide sensor for high spatial and temporal resolution measurements

我们建议开发和试验一种新的基于高性能荧光寿命的技术来传感海洋、大气和表层海洋中的二氧化碳(CO2)浓度。这项技术有望在气候研究的科学能力方面迈出重要的一步，类似于基于荧光寿命指示器的坚固而准确的氧传感器的出现，如果不是更大的话。二氧化碳是全球变暖和海洋酸化的主要载体。自工业革命以来，全球约30%的人为二氧化碳排放被海洋吸收。海洋继续充当汇的能力对大气二氧化碳、气候和海洋酸化的未来趋势至关重要。至关重要的是，来自海-气界面上方和下方表层的二氧化碳数据对通量研究具有科学意义。这类研究能够估计目前二氧化碳在大气和海洋之间的转移率。有证据表明，海-气通量背后的驱动力正在减弱，这是大气二氧化碳浓度年增长率加快的部分原因。该博士项目的总体目标是开发下一代海洋就地二氧化碳传感器，该传感器将利用荧光寿命技术，使用先进的双寿命参考指示器和采用高频光子计数和荧光衰减曲线拟合的光学询问技术。该传感器将利用二氧化碳的酸性特性来确定市场上可获得的(即GMBH)指示材料内的pH随二氧化碳的变化。传感器由pH敏感的荧光指示剂、CO2敏感的缓冲液、CO2不敏感的参考指示剂和支持气体渗透(但离子不渗透)的膜基质组成。博士项目的目标是1)优化荧光询问方法，2)确定传感器的精密度/准确度，3)确定传感器的温度和盐度相关性，4)开发温度补偿算法，5)微型外壳中的封装传感器，6)在沿海/海洋航行中测试二氧化碳传感器。这项研究将为英国在海洋传感器开发、二氧化碳海气交换、海洋酸化、海洋生物地球化学等方面的研究做出重要贡献，并将加强我们在气候变化研究方面的国际地位。这位博士生将利用NOCS现有的海洋微系统技术实验室和英国海洋酸化碳酸盐化学设施(使用NERC和EPSRC Capital Grants建立)，因此将在出色的分析设施中工作。博士生将在分析化学、传感器开发、碳酸盐化学和海洋生物地球化学方面接受出色的实践培训，并将学习分析化学和海洋生物地球化学的适当课程。南安普敦国家海洋学中心的海洋微系统中心[NOCS]将南安普顿大学的技能和科学资源与国家海洋研究中心的自然环境研究理事会传感器部门结合起来，提供了一个致力于海洋传感器技术前沿的国际知名研究小组[见www.soton.ac.uk/rmst]。这一庞大的群体的兴趣从微流体学和微机械专业知识延伸到生物污垢研究，为拟议领域的研究生培训提供了良好的环境。该小组的几个海洋就地传感器已经达到技术准备级别4-6，并通过Pi Achterberg为拟议的项目提供了额外的化学分析和生物地球化学技能。除了关键技能培训外，研究团队还将促进NERC资助的领先技术由博士生开发，以回答关键的环境问题。

We propose to develop and trial a novel high performance fluorescence lifetime based technology for sensing of carbon dioxide (CO2) concentrations in the marine atmosphere and surface ocean. The technology promises a significant step in scientific capability in climate research, similar if not greater than that enabled by the advent of robust and accurate oxygen sensors based on fluorescence lifetime indicators. CO2 is the main vector for global warming and ocean acidification. Since the industrial revolution, ca. 30% of the global anthropogenic CO2 emissions have been taken up by the oceans. The continued ability of the oceans to act as a sink is of critical importance for future trends in atmospheric CO2, climate and ocean acidification. Crucially, CO2 data from the surface zone immediately above and below the air-sea interface, is of scientific interest for flux studies. Such studies enable estimation of current transfer rates of CO2 between the atmosphere and the oceans. There is evidence that the driving force behind the air-sea flux of CO2 is decreasing and that this is partly responsible for the acceleration of atmospheric CO2 concentration annual growth rate. The overall aim of this PhD project is to develop the next generation of marine in situ pCO2 sensors that will utilise fluorescence life-time technology, using advanced dual lifetime referenced indicators and optical interrogation techniques employing high frequency photon counting and fluorescence decay curve fitting. The sensor will use the acidic character of CO2 to determine CO2-dependent change of pH inside a commercially available (Presens GmbH) indicator material. The sensors are built from a pH sensitive fluorescence indicator, a CO2 sensitive buffer, a CO2 insensitive reference indicator and a supporting gas-permeable (but ion impermeable) membrane matrix. The objectives of the PhD project are to 1) optimise the fluorescence interrogation approach, 2) determine precision/accuracy of sensor, 3) determine temperature and salinity dependency of sensor, 4) develop temperature compensation algorithm, 5) package sensor in miniaturised housing, 6) trial the CO2 sensor on coastal/oceanic voyages. This study will provide an important contribution to UK research on marine sensor development, air-sea exchange of CO2, ocean acidification, marine biogeochemistry, and the proposed research will strengthen our international position in climate change research. The PhD student will utilise the established laboratories for Marine Microsystem technology at NOCS and the UK Ocean Acidification Carbonate Chemistry Facilities (set-up using NERC and EPSRC Capital Grants), and therefore will work in excellent analytical facilities. The PhD student will receive an excellent hands-on training in analytical chemistry, sensor development, carbonate chemistry and marine biogeochemistry, and will undertake appropriate courses in analytical chemistry and marine biogeochemistry. The Centre for Marine Microsystems at the National Oceanography Centre, Southampton [NOCS] combines skills and scientific resources from across the University of Southampton with the Natural Environment Research Council sensor section at NOCS to provide an internationally known research group working at the leading edge of marine sensor technology [see www.soton.ac.uk/rmst]. This large group with interests extending from micro fluidics and micromechanical expertise to studies on biofouling, provides an excellent environment for the training of a research student in the proposed area. Several marine in situ sensors from the group are already at technology readiness levels 4-6, and additional chemical analytical and biogeochemical skills are provided through the PI Achterberg for the proposed project. The research team will facilitate NERC funded leading technology to be developed by the PhD student to answer crucial environmental questions, in addition to key skills training.