Measuring <scp>pH</scp> in low ionic strength glacial meltwaters using ion selective field effect transistor (ISFET) technology

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