Oxygen optodes as fast sensors for eddy correlation measurements in aquatic systems
Oxygen optodes as fast sensors for eddy correlation measurements in aquatic systems
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DOI：
10.4319/lom.2012.10.304
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发表时间：
2012-05-01
影响因子：
2.7
通讯作者：
Wenzhoefer, Frank
中科院分区：
文献类型：
--
作者：
Chipman, Lindsay;Huettel, Markus;Wenzhoefer, Frank
水涡相关技术可通过分析海底上方小测量体积内垂直流速和氧浓度的协方差，无创地确定沉积物 - 水界面的氧交换。该方法需要快速传感器，以便能够跟踪水流的快速变化以及由该水流输送的氧气，从而计算由湍流运动驱动的瞬时平流通量。在本文中，我们证明快速光学氧传感器（即光学探头）是此类测量中传统克拉克型电化学微电极的良好替代品。光学探头相对于微电极具有以下优势：对水流不敏感、不易受信号漂移影响、在典型野外条件下更耐用、价格更低且可维修。对光学探头和微电极对快速氧变化的响应时间的比较表明，优化后的光学探头与微电极具有相同的响应时间（162±66毫秒对160±57毫秒），并且足够快以捕捉与涡相关通量计算相关的氧波动。在淡水和海洋环境中，使用基于微电极的涡相关仪器和基于光学探头的涡相关仪器收集的底栖O - 2通量数据的并排比较表明，测量的通量之间没有显著差异。光学探头使得能够开发出更用户友好的涡相关仪器，该仪器结合了无创测量以及在较大覆盖面积上通量积分的优势，且使用相对坚固且价格较低的传感器。
The aquatic eddy-correlation technique can be used to noninvasively determine the oxygen exchange across the sediment-water interface by analyzing the covariance of vertical flow velocity and oxygen concentration in a small measuring volume above the sea bed. The method requires fast sensors that can follow the rapid changes in flow and the oxygen transported by this flow to calculate the momentary advective flux driven by turbulent motions. In this article, we demonstrate that fast optical oxygen sensors, known as optodes, represent a good alternative to the traditional Clark-type electrochemical microelectrodes for such measurements. Optodes have the advantage over microelectrodes of being insensitive to flow, less susceptible to signal drift, more durable under typical field conditions, less expensive, and repairable. Comparisons of the response times of optodes and microelectrodes to rapid oxygen changes showed that optimized optodes had the same response time (162 +/- 66 ms) as the microelectrodes (160 +/- 57 ms) and were fast enough to capture the oxygen fluctuations that are relevant for the eddy correlation flux calculations. Side by side comparisons of benthic O-2 flux data collected with microelectrode-based eddy correlation instruments and optode-based eddy correlation instruments in freshwater and marine environments showed no significant differences between the measured fluxes. The optodes allow the development of more user-friendly eddy correlation instruments that combine the advantages of non-invasive measurements and integration of fluxes over a large footprint area, using a relatively rugged and less expensive sensor.