pump is sometimes referred to as the “hard tissue” component of the biological pump. Some surface marine organisms, like Coccolithophores, produce hard structures out of calcium carbonate, a form of particulate inorganic carbon, by fixing bicarbonate. This fixation of DIC is an important part of the oceanic carbon cycle. Ca2+ + 2 → CaCO3 + CO2 + H2O While the biological carbon pump fixes inorganic carbon (CO2) into particulate organic carbon in the form of sugar (C6H12O6), the carbonate pump fixes inorganic bicarbonate and causes a net release of CO2. In this way, the carbonate pump could be termed the carbonate counter pump. It works counter to the biological pump by counteracting the CO2 flux from the biological pump. Measurement Oceanographers and engineers continue to find novel and more accurate methods of measuring carbon content in seawater. One method is to collect water samples and directly measure the DIC by using a TOC analyzer. Samples can be combined with stable isotope ratios 13C/12C, alkalinity measurements, and estimation of physical processes, to create diagnostic techniques. Researchers at Scripps Institution of Oceanography developed a tool that uses flow injection analysis to measures microfluidic samples of seawater and continuously monitor dissolved inorganic carbon content. See also Alkalinity (total alkalinity; AT) Bjerrum plot Dissolved organic carbon Fugacity (carbon dioxide fugacity; fCO2) Ocean acidification pH Total organic carbon References Chemical oceanography Analytical chemistry