Dissolved inorganic carbon profiles and fluxes determined
Limnol. Oceanogr., 43(5), 1998, 769-781 | DOI: 10.4319/lo.1998.43.5.0769
ABSTRACT: Submillimeter depth distributions of total dissolved inorganic carbon (DIC) were derived from pH and PCO2 profiles measured with microelectrodes in an organic-rich, laboratory-maintained sediment. The DTC profiles were used to calculate diffusive fluxes of DIC across the sediment-water interface. In two experiments, the calculated diffusive fluxes fell within ±50% of the total flux of DIC determined by core incubation. An assessment of errors suggests that the microelectrode-derived estimates are not significantly different from measured total DIC fluxes (P = 0.05). It is concluded, therefore, that pH and PCO2 microelectrode measurements can be paired to determine finescale pore-water DIC profiles and DIC diffusive fluxes. Problems will arise only in situations in which pH and PCO2 gradients are extremely steep or spatially heterogeneous; this is because these conditions can cause mismatching of pH and PCO2 measurements or CO2 system disequilibrium.