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首页> 外文期刊>Marine Chemistry >A new method for continuous measurements of O_2 in surface water in combination with pCO_2 measurements: Implications for gas phase equilibration
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A new method for continuous measurements of O_2 in surface water in combination with pCO_2 measurements: Implications for gas phase equilibration

机译：结合pCO_2测量连续测量地表水中O_2的新方法：气相平衡的意义

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An autonomous system for the recording of the surface water pCO_2 in the Baltic Sea was complemented by a module for continuous O_2 measurements. An optical O_2 sensor was used and in analogy to the determination of the pCO_2, the pO_2 was determined in the headspace of an equilibrator. By this procedure the automatic periodic calibration was considerably facilitated and biofouling was avoided. Uncertainties were associated with the use of a vented equilibrator. Due to the continuous pressure equalization with the ambient atmosphere, the headspace partial pressure of any gas (e.g. pO_2, pCO_2) reflects a steady state that may deviate substantially from the equilibrium. To calculate the true equilibrium pO_2 and thus the O_2 concentration in the water sample, we derived an equation that is based on the measurement of the headspace O_2 mol fraction, x_(O_2), and on the assumption that the surface water was saturated with atmospheric N_2 and Ar. Model calculations indicated that deviations from this assumption are less then 2% for most of the year. The combined pO_2/pCO_2 measurement system was deployed in July 2005 on a cargo ship that commutes regularly between the southwestern Baltic Sea and the Gulf of Finland. First results showed a reasonable agreement with O_2 data obtained at a measurement platform in the vicinity of the ship's track. The spatial resolution of the O_2 measurements was similar to that of the pCO_2 system and allowed the identification of small scale ( < 1 nautical mile) biogeochemical and hydrographical inhomogeneities.
机译：一个用于记录波罗的海中地表水pCO_2的自治系统由一个用于连续O_2测量的模块进行了补充。使用光学O_2传感器，类似于确定pCO_2，在平衡器的顶部空间确定了pO_2。通过该程序，大大方便了自动定期校准，避免了生物污染。不确定性与使用排气平衡器有关。由于与周围大气的连续压力平衡，任何气体（例如，pO_2，pCO_2）的顶部空间分压都反映出可能实质上偏离平衡状态的稳态。为了计算真实的平衡pO_2，从而计算出水样品中的O_2浓度，我们导出了一个基于顶空O_2摩尔分数x_（O_2）的测量，并假设地表水被大气饱和的方程N_2和Ar。模型计算表明，一年中大部分时间与该假设的偏差小于2％。组合的pO_2 / pCO_2测量系统于2005年7月部署在定期在波罗的海西南部和芬兰湾之间往返的货船上。初步结果表明，该数据与在船舶航迹附近的测量平台上获得的O_2数据具有合理的一致性。 O_2测量的空间分辨率与pCO_2系统的空间分辨率相似，可以识别小规模（<1海里）的生物地球化学和水文不均匀性。

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