Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements
Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements
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DOI：
10.1016/j.aca.2015.09.026
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发表时间：
2015-10-15
影响因子：
6.2
通讯作者：
Mowlem, Matthew C.
中科院分区：
文献类型：
--
作者：
Clarke, Jennifer S.;Achterberg, Eric P.;Mowlem, Matthew C.
海洋是人类活动产生的大气二氧化碳的主要汇，二氧化碳的吸收引起海洋碳酸盐系统的变化，并对植物群和动物群产生广泛的影响。这是至关重要的，以开发分析系统，使我们能够遵循增加海洋pCO（2）和相应的减少pH值。微型传感器系统使用固定化荧光指示点是有吸引力的，因为它们的简单的设计和低功耗的要求。该技术越来越多地用于海洋溶解氧的测量。我们提出了一个详细的方法，使用固定的荧光指示斑点，以确定在海洋沃茨的pH值范围内的pH值7.6-8.2。我们表征了温度（-0.046 pH/℃，从5到25 ℃）和盐度依赖性（-0.01 pH/psu，超过5-35），并对叶绿素对pH测量的影响进行了初步调查。在20 ℃下，传感器斑点的表观pK（a）为6.93。0.00014 R的漂移（约。0.0004 pH，25 ℃，盐度35），在3天的时间内，在基于实验室的漂移实验中观察到。我们实现了0.0074 pH单位的精度，并在南大洋作为正在进行的表面海洋传感器进行为期5周的测试部署期间观察到0.06 pH单位的漂移，并使用经过认证的参考材料进行了校正。用该算法对温度和盐度的依赖性进行了解释，R =（0.00034 - 0.17.pH + 0.15.S-2 + 0.0067.T - 0.0084.S）。1.075.这项研究提供了第一步的pH光电管系统适合自主部署。使用短持续时间的低功率照明（LED电流0.2 mA，5 μ s照明时间）提高了光斑的寿命和精度。pH指示剂点操作的进一步改进包括定期应用经认证的参考材料进行漂移校正和与分光光度pH系统的交叉校准。期望的未来发展应包括具有改进的响应时间和更接近海洋表面沃茨的pH的表观pK（a）值的新型荧光斑点。(C)2015年，作者。由爱思唯尔公司出版
The oceans are a major sink for anthropogenic atmospheric carbon dioxide, and the uptake causes changes to the marine carbonate system and has wide ranging effects on flora and fauna. It is crucial to develop analytical systems that allow us to follow the increase in oceanic pCO(2) and corresponding reduction in pH. Miniaturised sensor systems using immobilised fluorescence indicator spots are attractive for this purpose because of their simple design and low power requirements. The technology is increasingly used for oceanic dissolved oxygen measurements.We present a detailed method on the use of immobilised fluorescence indicator spots to determine pH in ocean waters across the pH range 7.6-8.2. We characterised temperature (-0.046 pH/degrees C from 5 to 25 degrees C) and salinity dependences (-0.01 pH/psu over 5-35), and performed a preliminary investigation into the influence of chlorophyll on the pH measurement. The apparent pK(a) of the sensor spots was 6.93 at 20 degrees C. A drift of 0.00014 R (ca. 0.0004 pH, at 25 degrees C, salinity 35) was observed over a 3 day period in a laboratory based drift experiment. We achieved a precision of 0.0074 pH units, and observed a drift of 0.06 pH units during a test deployment of 5 week duration in the Southern Ocean as an under way surface ocean sensor, which was corrected for using certified reference materials. The temperature and salinity dependences were accounted for with the algorithm, R = (0.00034 - 0.17.pH + 0.15.S-2 + 0.0067.T - 0.0084.S) . 1.075. This study provides a first step towards a pH optode system suitable for autonomous deployment. The use of a short duration low power illumination (LED current 0.2 mA, 5 mu s illumination time) improved the lifetime and precision of the spot. Further improvements to the pH indicator spot operations include regular application of certified reference materials for drift correction and cross-calibration against a spectrophotometric pH system. Desirable future developments should involve novel fluorescence spots with improved response time and apparent pK(a) values closer to the pH of surface ocean waters. (C) 2015 The Authors. Published by Elsevier B.V.