A laser based sensor for in situ, real time measurement of dissolved gas: application to CO2 in water

用于原位实时测量溶解气体的激光传感器：应用于水中二氧化碳

• 批准号: NE/L012367/1
• 负责人: Timothy Nightingale
• 金额: $ 18.72万
• 依托单位: Science and Technology Facilities Council
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FL012367%2F1
• 关键词: laser; based; sensor; situ; real

We propose the development of an instrument concept anticipated to enable for the first time the measurement of gases dissolved in water in-situ, in real time, at good resolution and in a compact and deployable package. Current measurement techniques for CO2 dissolved in water typically involve the equilibration of the amount of CO2 dissolved in water with that in a volume of gas, followed by an optical measurement of the CO2 in the gas; or equilibration with an electrolyte behind a semi-permeable membrane and a measurement of the acidity of the resulting liquid. Neither process is especially fast and the former is not suited to immersion in the ocean. Equilibration is a relatively slow process. Consequently it is difficult to measure oceanic CO2 profiles with high spatial or temporal resolution.We propose to develop some innovative laser-based methods to monitor gases dissolved in liquids. The first application targeted is dissolved CO2 in ocean water. With the proposed approach, no equilibration is required and good precision should be achievable in real time (seconds or better). The measurement is in principle tolerant of fouling and should be insensitive to a number of major instrumental and environmental parameters. The main tasks on the project will include initial design and trade-offs of the laser sensors, assembly and initial characterization, development of modulation schemes and quantitative data processing, and final laboratory tests to validate the technology. A fully developed instrument would be compact, have moderate power requirements, be immersible to significant depths and should be compatible with ship inlets, CTD (conductivity, temperature and depth) rosette water samplers and other ocean profilers.The proposed sensor would significantly contribute to the overall study of the Earth carbon cycle by enabling three dimensional measurements of CO2. More specific research areas include carbon chemistry and surface CO2 flux studies, CO2 exchange between marine biosphere and ocean, ocean CO2 circulation, and evaluation of CO2 seeps at ocean ridges and submarine volcanoes to understand deep carbon pathways to the oceans. Good spatial and temporal sampling, including at depth, are also potentially applicable to studies of small-scale or dynamic CO2 distributions, for validating CO2 sequestration experiments and for monitoring oil drilling operations.While we will be demonsrating our technique on CO2, the sensor concepts are widely applicable to the sensing of any molecular species dissolved in liquids. As such other numerous applications would be unlocked such as applications to water quality studies, or industrial characterisation of liquid contamination.

我们提出了一种仪器概念的发展，预计第一次能够测量溶解在水中的气体原位，在真实的时间，在良好的分辨率和紧凑和可部署的包。目前用于溶解在水中的CO2的测量技术通常涉及溶解在水中的CO2的量与一定体积的气体中的CO2的量的平衡，然后对气体中的CO2进行光学测量;或者用半透膜后面的电解质进行平衡并测量所得液体的酸度。这两个过程都不是特别快，前者不适合浸入海洋。平衡是一个相对缓慢的过程。因此，很难测量海洋CO2剖面的高空间或时间分辨率，我们建议开发一些创新的激光为基础的方法来监测溶解在液体中的气体。第一个目标应用是溶解在海水中的二氧化碳。利用所提出的方法，不需要平衡，并且应该在真实的时间（秒或更好）内实现良好的精度。测量原则上是耐污染的，并且应该对许多主要的仪器和环境参数不敏感。该项目的主要任务将包括激光传感器的初步设计和权衡，组装和初步表征，调制方案和定量数据处理的开发，以及验证该技术的最终实验室测试。一个充分开发的仪器将是紧凑的，具有中等的功率要求，可浸入相当深的深度，并应与船舶入口、CTD（电导率、温度和深度）玫瑰形水取样器和其他海洋剖面仪兼容，拟议的传感器将通过对CO2的三维测量，大大有助于对地球碳循环的全面研究。更具体的研究领域包括碳化学和表面二氧化碳通量研究、海洋生物圈和海洋之间的二氧化碳交换、海洋二氧化碳环流以及评估洋脊和海底火山的二氧化碳渗漏，以了解进入海洋的深层碳路径。良好的空间和时间采样，包括在深度，也有可能适用于小规模或动态CO2分布的研究，验证CO2封存实验和监测石油钻井作业。虽然我们将展示我们的技术对CO2，传感器的概念是广泛适用于任何分子物种溶解在液体中的传感。因此，其他许多应用将被解锁，例如水质研究或液体污染的工业表征的应用。