Solubility of oxygen in the major sea salts as a function of concentration and temperature

Frank J. Millero, Fen Huang, Arthur L. Laferiere

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70 Scopus citations


The solubility of oxygen has been measured in NaCl, Na2SO4, MgCl2 and MgSO4 solutions from 5 to 45°C from 0.1 to saturation. The solubilities, [O2], have been fitted to a Setschenow [J. Phys. Chem. 4 (1899) 117] type equation ln{[O2]0/[O2]} = lnγ = Am + Bm2 where the superscript zero is the solubility of oxygen in water, m is the molality and γ is the activity coefficient of O2. The adjustable parameters A and B are determined by least squares to equations of the form (T/K)A=a00+a01/T+a02ln T and B=b00 + b01/T+ b02ln T. The standard errors of all the fits of [O2] are less than ± 2.0 μmol (kg H2O)-1 for all the salts. The limiting values of ks=A for the solutions have been determined from the fits. The ionic values of ks for SO42- are not additive due to the strong interactions between Mg2+ and SO42-. The results have been interpreted using the Pitzer equations lnγO2 = 2 ∑c λO2cmc + 2 ∑a λO2ama + 2 ∑ca mcmaζO2ca where λO2i is a parameter that accounts for the interaction of O2 with cations (c) and anions (a) and ζO2ca accounts for interactions for O2 with the cation and anion (c-a). The coefficients (λO2i) determined for Na+, Cl- and SO42- are in reasonable agreement with the tabulations of Clegg and Brimblecombe [J. Phys. Chem. 93 (1990) 7237]. The values of λO2c for the interactions of Na+, Mg2+, SO42- and ζO2ca for the interactions of NaCl, Na2SO4, MgCl2 and MgSO4 with O2 from 5 to 45°C (T/K) have been fitted to equations of the form (λO2Cl=0) λO2Na = -24.2231 + 1169.14/T + 3.58915lnT λO2Mg = -40.3039 + 1912.70/T + 5.99055lnT λO2SO4 = 44.8440 - 1956.75/T - 6.69935lnT ζO2NaCl = 5.7292 - 260.89/T - 0.85431lnT ζO2MgCl2 = 19.715 - 888.35/T - 2.93893lnT ζO2Na2SO4 = 18.8007 - 862.37/T - 2.79870lnT ζO2MgSO4 = 25.4448 - 1186.25/T - 3.77264lnT These parameters represent the oxygen solubilities to ± 2.0 μmol (kg H2O)-1 over the entire range of temperature and concentration. The resulting coefficients for the major sea salts can be used to estimate the solubility of oxygen in all natural waters over a wide range of temperature and ionic strength.

Original languageEnglish (US)
Pages (from-to)217-230
Number of pages14
JournalMarine Chemistry
Issue number4
StatePublished - Jul 24 2002


  • Concentration
  • Major sea salts
  • Solubility of oxygen
  • Temperature

ASJC Scopus subject areas

  • Oceanography
  • Chemistry(all)
  • Environmental Chemistry
  • Water Science and Technology


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