Estimating the contribution of organic bases from microalgae to the titration alkalinity in coastal seawaters

J. Martín Hernández-Ayon, Alberto Zirino, A. G. Dickson, Tania Camiro-Vargas,E. Valenzuela

Limnol. Oceanogr. Methods 5:225-232 (2007) | DOI: 10.4319/lom.2007.5.225

ABSTRACT: This study reports the potential contribution of organic bases to the alkalinity of seawater samples. The concentration of organic bases in these samples was inferred from the difference between the measured alkalinity and that calculated from a knowledge of pH and the concentrations of the various inorganic acid-bases species such as total carbon and total boron, etc. Significant concentrations of such organic bases were measured in cultures of the marine microalgae Rhodomonas sp. (800 µmol kg-1) and Isochrysis aff. Galbana (400 µmol kg-1), as well as in three marine environments (Northern Gulf of California, México; San Quintín Bay, B.C. Mexico and San Diego Bay). These three sites are characterized by significant biological activity and restricted mixing, and the organic bases were found at concentrations greater than 50 µmol kg-1 in each of these three locations.