## Abstract

The solubility of oxygen has been measured in NaCl, Na_{2}SO_{4}, MgCl_{2} and MgSO_{4} solutions from 5 to 45°C from 0.1 to saturation. The solubilities, [O_{2}], have been fitted to a Setschenow [J. Phys. Chem. 4 (1899) 117] type equation ln{[O_{2}]^{0}/[O_{2}]} = lnγ = Am + Bm^{2} where the superscript zero is the solubility of oxygen in water, m is the molality and γ is the activity coefficient of O_{2}. The adjustable parameters A and B are determined by least squares to equations of the form (T/K)A=a_{00}+a_{01}/T+a_{02}ln T and B=b_{00} + b_{01}/T+ b_{02}ln T. The standard errors of all the fits of [O_{2}] are less than ± 2.0 μmol (kg H_{2}O)^{-1} for all the salts. The limiting values of k_{s}=A for the solutions have been determined from the fits. The ionic values of k_{s} for SO_{4}^{2-} are not additive due to the strong interactions between Mg^{2+} and SO_{4}^{2-}. The results have been interpreted using the Pitzer equations lnγ_{O2} = 2 ∑_{c} λ_{O2c}m_{c} + 2 ∑_{a} λ_{O2a}m_{a} + 2 ∑_{c} ∑_{a} m_{c}m_{a}ζ_{O2ca} where λ_{O2}i is a parameter that accounts for the interaction of O_{2} with cations (c) and anions (a) and ζ_{O2}ca accounts for interactions for O_{2} with the cation and anion (c-a). The coefficients (λ_{O2}i) determined for Na^{+}, Cl^{-} and SO_{4}^{2-} are in reasonable agreement with the tabulations of Clegg and Brimblecombe [J. Phys. Chem. 93 (1990) 7237]. The values of λ_{O2}c for the interactions of Na^{+}, Mg^{2+}, SO_{4}^{2-} and ζ_{O2}ca for the interactions of NaCl, Na_{2}SO_{4}, MgCl_{2} and MgSO_{4} with O_{2} from 5 to 45°C (T/K) have been fitted to equations of the form (λ_{O2}Cl=0) λ_{O2Na} = -24.2231 + 1169.14/T + 3.58915lnT λ_{O2Mg} = -40.3039 + 1912.70/T + 5.99055lnT λ_{O2SO4} = 44.8440 - 1956.75/T - 6.69935lnT ζ_{O2NaCl} = 5.7292 - 260.89/T - 0.85431lnT ζ_{O2MgCl2} = 19.715 - 888.35/T - 2.93893lnT ζ_{O2Na2SO4} = 18.8007 - 862.37/T - 2.79870lnT ζ_{O2MgSO4} = 25.4448 - 1186.25/T - 3.77264lnT These parameters represent the oxygen solubilities to ± 2.0 μmol (kg H_{2}O)^{-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 language | English (US) |
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Pages (from-to) | 217-230 |

Number of pages | 14 |

Journal | Marine Chemistry |

Volume | 78 |

Issue number | 4 |

DOIs | |

State | Published - Jul 24 2002 |

## Keywords

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

## ASJC Scopus subject areas

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