Measuring pH in glacial meltwaters is challenging, because they are cold, remote, subject to freeze‐thaw cycles and have low ionic strength. Traditional methods often perform poorly there; glass electrodes have high drift and long response times, and spectrophotometric techniques are unpractical in cold, remote environments. Ion selective field effect transistor (ISFET) sensors are a promising alternative, proven in marine and industrial applications. We assess the suitability of two models of ISFET, the Honeywell Durafet and Campbell Scientific Sentron, for use in glacial melt through a series of lab and field experiments. The sensors have excellent tolerance of freeze‐thaw and minimal long‐term drift, with the Durafet experiencing less drift than the Sentron model. They have predictable response to temperature, although the Durafet housing causes some lag during rapid cycling, and the impact of stirring is an order of magnitude less than that of glass electrodes. At low ionic strength (< 1 mmol L⁻¹), there is measurable error, but this is quantifiable, and less than glass electrodes. Field tests demonstrated low battery consumption, excellent longevity and resistance to extreme conditions, and revealed biogeochemical processes that were unlikely to be recorded by standard methods. Meltwater pH in two glacial catchments in Greenland remained > 7 with consistent diurnal cycles from the very first meltwater flows. We recommend that ISFET sensors are used to assess the pH of glacial meltwater, since their tolerance is significantly better than alternative methods: the Durafet is accurate to ± 0.2 pH when waters are > 1 mmol L⁻¹ ionic strength, and ± 0.3 pH at < 1 mmol L⁻¹.

中文翻译：

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使用离子选择性场效应晶体管（ISFET）技术测量低离子强度冰川融化水中的pH

测量冰川融化水中的pH值具有挑战性，因为它们寒冷，偏远，易受冻融循环的影响，并且离子强度低。传统方法在该处通常效果不佳；玻璃电极漂移高且响应时间长，而分光光度技术在寒冷，偏远的环境中不切实际。离子选择性场效应晶体管（ISFET）传感器是一种有前途的替代产品，已在船舶和工业应用中得到验证。我们通过一系列实验室和现场实验评估了两种ISFET模型（霍尼韦尔·杜拉夫特和坎贝尔科学Sentron）在冰川融化中的适用性。传感器具有出色的抗冻融能力，并且长期漂移极小，Durafet的漂移比Sentron模型要小。他们对温度有可预测的响应，尽管Durafet外壳在快速循环过程中会引起一些滞后，并且搅拌的影响要比玻璃电极小一个数量级。在低离子强度（<1 mmol L^-1），存在可测量的误差，但这是可量化的，并且小于玻璃电极。现场测试表明电池消耗低，寿命长，对极端条件具有抵抗力，并揭示了用标准方法不太可能记录的生物地球化学过程。格陵兰岛两个冰川集水区的融水pH值始终保持> 7，并且从最初的融水流开始就具有一致的昼夜周期。我们建议将ISFET传感器用于评估冰川融化水的pH值，因为它们的耐受性明显优于其他方法：当水的离子强度> 1 mmol L ^-1时，Durafet的准确度为±0.2 pH，在水的离子强度为±0.3 pH时，准确度为±0.3 pH。 <1 mmol L ^-1。