The compressibility of seawater from 0 to 95°C at 1atm

Frank J. Millero, Fen Huang

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Abstract

Measurements on the speed of sound (U) in seawater as a function of salinity at 1atm (P=0bar applied pressure) have been measured from 25 to 95°C. The new measurements have been combined with the earlier studies to determine the adiabatic compressibility (βS=-(1/ρ)(∂ρ/∂P)S) of seawater from 0 to 95°CβS=1/ρU2where ρ is the density and S is the entropy of seawater. The isothermal compressibility of seawater were determined fromβT=βSα2T/ρCpwhere the thermal expansively, α=-(1/ρ)(∂ρ/∂T)P and heat capacity (Cp) were determine from earlier measurements. The values of the isothermal compressibility at 1atm (βT0) have been used to estimate the effect of pressure on the secant bulk modulus of seawater (KP at applied pressure P)KP=v0P/v0-vP=K0+A P+B P2where the specific volume v=1/ρ and K0=1/(βT0). The values of A and B at high pressures have been determined from literature high pressure measurements. This allows one to make reasonable estimates of the density of seawater as a function of pressure to 100°C when seawater is used as a cooling agent and for desalination (Feistel, 2010).

Original languageEnglish (US)
Pages (from-to)149-154
Number of pages6
JournalMarine Chemistry
Volume126
Issue number1-4
DOIs
StatePublished - Sep 20 2011

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Keywords

  • Compressibility of seawater
  • Effect of pressure on density of seawater
  • Equation of state of seawater
  • Secant bulk modulus
  • Speed of sound
  • Temperature

ASJC Scopus subject areas

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

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