Spectrophotometric Determination of Carbonate Ion Concentrations: Elimination of Instrument-Dependent Offsets and Calculation of In Situ Saturation States
This work describes an improved algorithm for spectrophotometric determinations of seawater carbonate ion concentrations ([CO32–]spec) derived from observations of ultraviolet absorbance spectra in lead-enriched seawater. Quality-control assessments of [CO32–]spec data obtained on two NOAA research cruises (2012 and 2016) revealed a substantial intercruise difference in average Δ[CO32–] (the difference between a sample’s [CO32–]spec value and the corresponding