FRANKLIN CRUISES FR 8/90, 5/92 AND 8/93
DATA DOCUMENTATION
JGOFS WESTERN EQUATORIAL PACIFIC PROCESS STUDY

[1] General:

Parameter:			Surface pH
Level 1:			<Yes > 
Principal Investigator:	Denis Mackey 
Institute Address:		CSIRO Division of Marine Research
E-Mail Address:		Denis.Mackey@marine.csiro.au

List of Parameters:	pH
List of Units:			Synthetic seawater, ‘free‘ hydrogen ion concentration

[2] Sampling:

Gear (e.g. CTD, pump, etc.):	Oceandata Thermosalinograph. 
Standard Depths:	Intake at 3 m
Chemicals used:			Hansson Buffers
Special Procedures:	Water taken from thermosalinograph via a T-connection. Flow was controlled at 500 ml min-1 by a peristaltic pump. pH electrode output (mV) and seawater temperature were logged at 1 sec intervals and stored as 1 min averages
Comments and Notes:	Electrode calibrated daily against Hansson buffers which were made up every 1-2 days

3] Analysis:

Instrument:	Ross electrode (Orion 81-03SC), Radiometer PHM 85 pH meter with temperature probe T801. In-house flow cell fitted with a pulse dampener and Pt earth for seawater. 

Method:	See Mackey et al,. Deep-Sea Research 42, 499-533, 1995.
Precision:	Estimated as 0.001, accuracy estimated as 0.007
Comments:	Electrode drift was taken into account by fitting a linerar (FR08/90) or cubic (FR05/92 and FR08/93) regression line to the emf. On FR08/93, two Ross electrodes were used and the RMS difference between them was 0.004. The temperature response of the Ross electrodes in seawater and in buffers were determined pre-cruise. The pH was calculated at the thermosalinograph temperature according to the method of Fuhrman and Zirino, Deep-Sea Research, 35, 197-208, 1988. 

[4] Results:

Quality of Data:	On FR05/92, the difference between pCO2 calculated from the pH and direct measurements had an RMS difference of  8 atm. 
Known Problems:	

 [5] Brief description of analytical method 
Mackey, D. J., Higgins, H. W., Mackey, M. D. and Holdsworth, D. (1998) Algal class abundances in the western equatorial Pacific: estimation from HPLC measurements of chloroplast pigments using CHEMTAX. Deep-Sea Research, 45, 1441-1468.

Mackey, D. J., Parslow, J. S., Griffiths, F. B., Higgins, H. W. and Tilbrook, B. (1997) Phytoplankton productivity and the carbon cycle in the western equatorial Pacific under ENSO and non-ENSO conditions. Deep-Sea Research, 44, 1951-1978.
. 

[6] Comments: