Guidelines for sampling and determination of pH in seawater.

Abstract

Since ocean acidification is a growing concern, monitoring of pH is necessary for studies of acidification and its effects on the carbonate buffer system. As many important biological processes are likely to be affected by rapid changes in pH, it is important to include accurate determination of pH among monitoring parameters. pH is operationally defined, and a number of pH scales are used in environmental monitoring. The NBS (National Bureau of Standards) scale is suitable for waters of low ionic strength, and used for freshwater monitoring. The total hydrogen ion scale is often used for pH determinations in oceanic waters. The salinity gradient from the Bothnian Bay to Skagerrak, or from surface to deep water in the Baltic Proper, makes it difficult to select a pH scale that would be suitable for the entire Baltic area. pH is also used in marine environmental monitoring as a co-factor in measurements of primary production.