Characterization of a Time-Domain Dual Lifetime Referencing pCO2 Optode and Deployment as a High-Resolution Underway Sensor across the High Latitude North Atlantic Ocean
Characterization of a Time-Domain Dual Lifetime Referencing pCO2 Optode and Deployment as a High-Resolution Underway Sensor across the High Latitude North Atlantic Ocean
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DOI：
10.3389/fmars.2017.00396
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发表时间：
2017-01-01
影响因子：
3.7
通讯作者：
Achterberg, Eric P.
中科院分区：
文献类型：
--
作者：
Clarke, Jennifer S.;Humphreys, Matthew P.;Achterberg, Eric P.
海洋是人为二氧化碳（CO2）的主要汇，CO2吸收导致海洋化学变化。为了监测这些变化，并为生物和地球化学研究提供化学背景，需要高质量的CO2分压（pCO（2））传感器，具有适当的准确度和精度的海洋测量。光电二极管具有原位测量pCO（2）的潜力，而不需要pCO（2）系统中通常使用的湿化学品或庞大的气体平衡室。然而，与更成熟的基于平衡器的pCO（2）系统相比，光选元件仍处于早期开发阶段。在这项研究中，我们进行了一个基于实验室的表征时域双寿命参考pCO（2）光电管系统。用低强度光（0.2mA，0.72mW）照射pCO（2）光电二极管点以使点光漂白最小化。在部署之前使用实验气体校准装置校准该点，在25摄氏度下确定的响应时间（τ（63））为50秒。pCO（2）光电探测器作为一个自主的舰载航行系统部署在高纬度北大西洋，分辨率为每小时约10次测量。光电二极管数据通过基于二级船载平衡器的红外pCO（2）仪器进行验证，并根据溶解无机碳和总碱度的离散样本计算pCO（2）。使用营养物和溶解氧等补充变量进一步验证pCO（2）光电二极管数据。pCO（2）传感器的船载精度为9.5 μ atm，这是根据经认证的参考物质的重复测量和在站上海水测量的标准偏差确定的。最后，光电探测器部署数据用于评估对pCO（2）的物理和地球化学控制。
The ocean is a major sink for anthropogenic carbon dioxide (CO2), with the CO2 uptake causing changes to ocean chemistry. To monitor these changes and provide a chemical background for biological and biogeochemical studies, high quality partial pressure of CO2 (pCO(2)) sensors are required, with suitable accuracy and precision for ocean measurements. Optodes have the potential to measure in situ pCO(2) without the need for wet chemicals or bulky gas equilibration chambers that are typically used in pCO(2) systems. However, optodes are still in an early developmental stage compared to more established equilibrator-based pCO(2) systems. In this study, we performed a laboratory-based characterization of a time-domain dual lifetime referencing pCO(2) optode system. The pCO(2) optode spot was illuminated with low intensity light (0.2 mA, 0.72 mW) to minimize spot photobleaching. The spot was calibrated using an experimental gas calibration rig prior to deployment, with a determined response time (tau(63)) of 50 s at 25 degrees C. The pCO(2) optode was deployed as an autonomous shipboard underway system across the high latitude North Atlantic Ocean with a resolution of ca.10 measurements per hour. The optode data was validated with a secondary shipboard equilibrator-based infrared pCO(2) instrument, and pCO(2) calculated from discrete samples of dissolved inorganic carbon and total alkalinity. Further verification of the pCO(2) optode data was achieved using complimentary variables such as nutrients and dissolved oxygen. The shipboard precision of the pCO(2) sensor was 9.5 it mu atm determined both from repeat measurements of certified reference materials and from the standard deviation of seawater measurements while on station. Finally, the optode deployment data was used to evaluate the physical and biogeochemical controls on pCO(2).