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CRUISE REPORT: A17
(Updated Dec 2014)


Highlights
                             Cruise Summary Information
               Section Designation  A17 (aka: FICARAM VI, HE091)
Expedition designation (ExpoCodes)  29HE20030408
                  Chief Scientists  Aida F. Rios / IIM-CSIC
                             Dates  2003 April 8 - 2003 April 24 
                              Ship  R/V Hespérides 
                     Ports of call  
                                               31° N
             Geographic Boundaries  70° W                 15° W
                                               23° N

                          Stations  7
      Floats and drifters deployed  0
    Moorings deployed or recovered  0

                                Contact Information:

                                    Aida F. Rios
          Grupo de Oceanologia • Instituto de Investigaciones Marinas.CSIC 
                       c/Eduardo Cabello 6 • 36208 Vigo, Spain 
              Tel: 34-986-231930 (Ext. 371) • Email: aida@iim.csic.es
























                             CRUISE FICARAM VI

R/V  Hespérides
Cruise:  He091
Dates:  8 to 24 April 2003
Chief scientist:  Aida F. Rios (IIM-CSIC)

Alkalinity and pH responsible (A.F. Rios)
DIC analysis responsible (coulometric method):  Rik Wanninkohf  (NOAA/AOML)
Nutrients analysis responsible:  Carmen G. Castro (IIM-CSIC) 

During the cruise FICARAM VI, seven stations were performed.  Alkalinity 
and pH were measured on board. The variables of carbon system, pH and 
alkalinity, in surface waters together with the fCO2 measured, were used to 
study the internal consistency of the measurements.

pH was measured spectrophotometrically following Clayton and Byrne (1993). 

Total Alkalinity (TA) was measured using potentiometric titrations with 
hydrochloric acid to a final pH of 4.40 (Pérez and Fraga, 1987). The 
electrodes were standardised using a buffer of pH 4.42 made in CO2 free 
seawater (Pérez et al., 2002). 

Dissolved oxygen was determined by Winkler potentiometric titration. The 
estimated analytical error was ±1 µmol⋅kg-1. Oxygen saturation was 
calculated following Benson and Krause equation (UNESCO, 1986).

Nutrient samples were frozen before the analysis. Nutrient concentrations 
were determined by segmented flow analysis with Alpkem system, following 
Hansen and Grasshoff (1983) with some improvements (Mouriño and Fraga, 
1985; Álvarez-Salgado et al., 1992). The analytical error was ±0.05 µmol⋅kg-1 
for nitrate, ±0.05 µmol⋅kg-1 for silicic acid and ±0.01 µmol⋅kg-1 for 
phosphate. 

To check the accuracy of the pH and TA measurements, samples of CO2 
reference material (CRM, batch 54 distributed by A.G. Dickson from the 
Scripps Institution of Oceanography) were analysed during the cruises. The 
uncertainties of pH and alkalinity were ±0.002 and ±0.7 µmol kg-1, 
respectively.  The corresponding theoretical pH(25T) value (7.918) for this 
batch was calculated using the dissociation constants from Lueker et al. 
(2000), which was in agreement with the theoretical value (±0.0002).

Figure 1 compares the CO2 fugacity (fCO2) values measured at every station 
sampled during FICARAM VI cruise and those calculated from pH(T) and total 
alkalinity with the Mehrbach et al. (1973) dissociation constants  refitted 
by Dickson and Millero (1987) dissociation constants. The agreement between 
both fCO2 is excellent (r(^2) =0.94), confirming the good internal consistency 
of our measurements. The average and standard deviation of the differences 
between both calculated and measured CO2 was -0.5±3.1 µatm.

Figure 2 compares the DIC measured using coulometric method with those 
calculated from pH and total alkalinity with the Mehrbach et al. (1973) 
dissociation constants  refitted by Dickson and Millero (1987). The 
agreement between both DIC is excellent (r(^2) =0.995). The average and 
standard deviation of the differences between both calculated and measured 
DIC was -5.0 ± 4.7 µmol/kg.



FIGURE 1: Relationship between measured CO2 fugacity and that calculated as 
          a function of TA and pH measured at the surface of the FICARAM VI 
          stations.

FIGURE 2: Relationship between measured DIC and that calculated as a 
          function of TA and pH 



REFERENCES

Alvarez-Salgado X.A., Fraga F., Perez F.F., 1992. Determination of nutrient 
    salts by automatic methods both in seawater and brackish waters: The 
    phosphate blank. Marine Chemistry, 39, 311-319.

Clayton T.D., Byrne R.H., 1993. Spectrophotometric seawater pH 
    measurements: total hydrogen ion concentration scale concentration 
    scale calibration of m-cresol purple and at-sea results. Deep-Sea Res. 
    I, Vol. 40, 10, 2115-2129.

Dickson A.G., Millero. F.J., 1987. A comparison of the equilibrium 
    constants for the dissociation of carbonic acid in seawater media. 
    Deep-Sea Res., 34, 1733-1743

Hansen H.P., Grasshoff K., 1983. Automated Chemical Analysis. In: K. 
    Grasshoff, M. Ehrhardt and K. Kremlig (Editors), Methods of Seawater 
    Analysis. Verlag Chemie, Weinheim, 419 pp., 1983.

Mehrbach C., Culberson C.H., Hawley J.E., Pytkowicz,R.M., 1973. Measurement 
    of the apparent dissociation constants of carbonic acid in seawater at 
    atmospheric pressure. Limnology and Oceanography, 18, 897-907

Mouriño C., Fraga F., 1985: Determinacion de nitratos en agua de mar. 
    Investigacion Pesquera, 49, 81-96.

Pérez F.F., Fraga F., 1987. A precise and rapid analytical procedure for 
    alkalinity determination. Marine Chemistry, 21, 169-182.

Pérez F.F., Ríos A.F., Rellán T., Álvarez M., 2000. Improvements in a fast 
    potentiometric seawater alkalinity determination. Ciencias Marinas, 26, 
    463-478.



DATA PROCESSING NOTES

2010-08-26  BTL     Website Updated  Copied from CARINA collection
    Justin  This bottle file was part of the CARINA collection compiled 
    Fields  by Bob Key.   

2014-12-16  CrsRpt  Website Updated  PDF version online
     Jerry  I've uploaded a new PDF version of the cruise report to the
     Kappa  CCHDO website. 

            It includes all the reports provided by the cruise PIs, summary 
            pages and CCHDO data processing notes, as well as a linked 
            Table of Contents and links to figures.

2014-12-18  CrsRpt  Website Updated  TXT version online
     Jerry  I've uploaded a new TXT version of the cruise report to the
     Kappa  CCHDO website. 

            It includes all the reports provided by the cruise PIs, summary 
            pages and CCHDO data processing notes
