Fluorescence Lifetime In situ Carbon Dioxide Sensors for Oceanic Flux and Acidification Studies at High Spatial and Temporal Resolution

该项目将研究高性能传感器，用于对海洋沃茨和海洋表面附近大气中的二氧化碳（CO2）浓度进行高质量测量。这项技术同样可以用于其他应用，包括淡水研究。该传感器技术基于一种指示剂材料，该材料在CO2存在时会改变其光学特性。具体地，指示剂是荧光的（即，当暴露于高频光时，其发射较低频率的光）。这种荧光在高频光关闭后持续很短的时间。荧光持续的时间长度（荧光寿命）随CO2的浓度而变化。荧光技术特别适合于低水平和高性能的测量。目前尚未对这些指标在表层海洋中的使用进行评估，而且这些指标可能会长期漂移。为了解决这个问题，拟议的研究将调查用于测量荧光寿命的光学测量的新技术（减少指示剂的漂白），将调查即使在远程操作时也能解释传感器漂移的新方法，并将全面评估这种新技术的新应用。这是朝着创建适合在该应用中广泛使用的鲁棒且低成本的原位CO2传感技术迈出的第一步。二氧化碳（CO2）是全球变暖的主要原因，也溶解在海水中，增加了海洋的酸度，这可能对海洋生物和环境产生进一步的负面影响。在一些地点，特别是在海洋表层和海洋低层大气中，准确测定CO2浓度，并在短时间内进行测量，对于评估海洋对大气CO2浓度增加的反应至关重要。至关重要的是，来自海-气界面上方和下方的数据具有重要的科学意义，特别是对于预测海洋吸收或排放多少二氧化碳。使用基于船的系统或大型复杂的潜水系统的电流测量技术太昂贵且体积太大而不能实现广泛的重复测量。这就需要一千万份空气中一份CO2的精确度（在空气中）和类似的测量水中溶解CO2的性能。我们建议在代表常见远洋航行工具的条件下评估该技术，例如浮子，剖面浮子（即定期下沉到一定深度，然后浮出水面），并在商业船舶上使用机会性部署（例如通过分析渡轮和货船上的发动机冷却水）。这包括在大气中的测量，其中冲洗和喷雾是常见的，并在水中，而受到振动和大的压力变化。这项研究的潜在商业价值将与切尔西技术集团（一家英国公司）一起探讨。

This project will investigate high performance sensors for making high quality measurements of carbon dioxide (CO2) concentrations in both ocean waters and the atmosphere close to the ocean surface. This technology could equally be used in other applications including freshwater studies. The sensor technology is based on an indicator material that changes its optical properties in the presence of CO2. Specifically the indicator is fluorescent (i.e. when exposed to a high frequency light it emits lower frequency light). This fluorescence persists for a short time after the high frequency light is turned off. The length of time that the fluorescence persists (the fluorescence lifetime) changes with the concentration of CO2. Fluorescence techniques are particularly well suited to low level and high performance measurement. Currently such indicators have not been evaluated for use in the surface ocean, and can suffer from long-term drift. To combat this the proposed research will investigate novel techniques for the optical measurement used to measure fluorescence lifetime (that reduce bleaching of the indicator), will investigate novel methods of accounting for sensor drift even when operated remotely, and will comprehensively evaluate this new technology for this new application. This is the first step towards the creation of robust and low cost in situ CO2 sensing technology suitable for widespread use in this application. Carbon dioxide (CO2) is the main cause of global warming and also dissolves in seawater, increasing the acidity of the oceans which can have further negative consequence on marine life and the environment. The accurate determination of CO2 concentration in a number of locations and with short intervals between measurements, particularly in the surface ocean and lower oceanic atmosphere, is critical for assessing the response of the oceans to increasing atmospheric CO2 concentrations. Crucially data from immediately above and below the air-sea interface is of critical scientific interest particularly for predicting how much CO2 is absorbed or emitted by the oceans. Current measurement techniques using ship based systems or large complex submersible systems are too expensive and bulky to enable widespread repeated measurements. This requires accuracy of one part CO2 in ten million parts air (in air) and a similar performance for measurement of dissolved CO2 in water. We propose to evaluate the technology in conditions representative of common ocean going vehicles such as floats, profiling floats (i.e. periodically sinking to depth and then surfacing), and using opportunistic deployments on commercial ships (e.g. by analysing engine coolant water on ferries and cargo vessels). This includes measurements in the atmosphere where wash-over and spray are common, and in water whilst subject to vibration and large pressure changes. The potential commercial value of this research will be explored with Chelsea Technologies Group (a UK company).