Ocean pCO2 calculated from dissolved inorganic carbon, alkalinity, and equations for K1 and K2: validation based on laboratory measurements of CO2 in gas and seawater at equilibrium

摘要: Abstract The partial pressure of carbon dioxide in the ocean's surface waters, precisely expressed as fugacity ( f CO 2 ) is determined from dissolved inorganic (DIC) and total alkalinity (TA), first second dissociation constants carbonic acid, K 1 . original measurements reported by Mehrbach et al. [Mehrbach, C., Culberson, C.H., Hawley, J.E., Pytkowicz, R.M., 1973. Measurement apparent acid seawater at atmospheric pressure. Limnol. Oceanogr. 18, 897–907] are reformulated to give equations for p (p =−log 10 a function temperature salinity, consistent with “total hydrogen ion” concentration scale: =3633.86/T−61.2172+9.67770 ln T−0.011555 S+0.0001152 S =471.78/T+25.9290−3.16967 T−0.01781 S+0.0001122 By equilibrating solutions gas mixtures known composition, we demonstrate that above formulations calculated values agree equilibrated 0.07±0.50% (95% confidence interval, up 500 μatm). Formulations based on other studies resulted approximately 10% lower than measurements. Equilibrations μatm yielded measured higher average 3.35±1.22% interval). cause dependence results not known. uncertainties were combined analytical typical contemporary DIC TA reveal expected reliability these parameters. For example, an uncertainty 1.0 μmol kg −1 (1 standard deviation (s.d.)) will result 1% or ±3.5 350 s.d.).