High spatial resolution Alkalinity and pH measurements by IIM-CSIC group along 24.5°N during the R/V Hesperides WOCE Section A05 cruise (July 14 - August 15, 1992)

Abstract

This dataset gathers discrete measurements of CO2 (pH and alkalinity) and hydrographic variables (salinity, temperature, dissolved oxygen, nitrate, phosphate and silicate) obtained during the cruise WOCE Section A05 carried out from 14 July to 15 August 1992. The pH was measured potentiometrically in the NBS scale with a combined glass electrode associated to a thermo-compensator and referred to 15ºC (Perez and Fraga, 1987a). The method had a shipboard precision of 0.005 units, based on 184 replicate analysis corresponding to two different oceanographic bottles fired at the same depth at each station (Ríos and Rosón, 1996). AT measurements were made by titration of seawater with potentiometric endpoint detection (Perez and Fraga, 1987b), reaching a precision of ±1 µmol kg-1. Dissolved oxygen was analyzed following the widely applied Winkler method. Determinations of nitrate, phosphate and silicate were carried out following methods described by Hansen and Grassoff (1983) Salinity and Temperature were recorded with a CTD probe