ments in estuaries are considered. To do this, the pH measurements with respect to the concentration (
) and NBS scales were carried out using a cell with a liquid junction:
The Measurement of pH Values in Seawater Using a Cell
without a Liquid Junction
P. Ya. Tishchenko1, R. V. Chichkin1, E. M. Il’ina1, and C. S. Wong2
1Pacific Oceanological Institute, Vladivostok, Russia
2Institute of Ocean Sciences, Sidney, Canada
Received September 12, 2000
Abstract—Based on the example of the Razdol’naya River–Amur Bay estuary, the problems of pH measure-
ments in estuaries are considered. To do this, the pH measurements with respect to the concentration () and
NBS scales were carried out using a cell with a liquid junction:
An analysis of theoretical errors appearing in measuring the pH value with cell (I) showed that, when calculat-
ing the carbonate parameters, errors arise amounting to hundreds of µatm for the partial pressure of carbon diox-
ide and to tens of µmol/kg for the dissolved inorganic carbon. The present study proposes to measure the pH
values with respect to the conventional scale by Pitzer (
) by means of a cell without a liquid junction:
To calibrate cell (II), a TRIS–TRIS · HCl–NaCl–H2O buffer solution was used (mTRIS =mTRISHCl = 0.04,
mNaCl= 0.3, pc(aH/
Na) = 8.1058; t = 25
). A standard deviation of 
0.003 pH units was obtained from the
parallel measurements with cell (II). A thermodynamically justified way to convert the 
values into the 
concentration scale using precise data on the measurements of the EMF value in a cell consisting of plat-
inum–hydrogen and silver–chloride electrodes is suggested [12].
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