Buffers of known quality for the calibration of seawater pHTmeasurements are not widely or commercially available. Although there exist published compositions for the 0.04 mol kg‐H2O−1equimolar buffer 2‐amino‐2‐hydroxymethyl‐1,3‐propanediol (TRIS)‐TRIS · H+in synthetic seawater, there are no explicit procedures that describe preparing this buffer to achieve a particular pHTwith a known uncertainty. Such a procedure is described here which makes use of easily acquired laboratory equipment and techniques to produce a buffer with a pHTwithin 0.006 of the published pHTvalue originally assigned by DelValls and Dickson (1998), 8.094 at 25°C. Such a buffer will be suitable for the calibration of pH measurements expected to fulfil the “weather” uncertainty goal of the Global Ocean Acidification Observation Network of 0.02 in pHT, an uncertainty goal appropriate to “identify relative spatial patterns and short‐term variation.”
Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
-
more » « less
Abstract -
Abstract. The number and quality of ocean pH measurements have increasedsubstantially over the past few decades such that trends, variability, andspatial patterns of change are now being evaluated. However, comparing pHchanges across domains with different initial pH values can be misleadingbecause a pH change reflects a relative change in the hydrogen ionconcentration ([H+], expressed in mol kg−1) rather than anabsolute change in [H+]. We recommend that [H+] be used inaddition to pH when describing such changes and provide three examplesillustrating why.more » « less
