Density and derived properties of standard seawater up to high pressure in stable and metastable states

• Published in: Deep-sea research. Part I, Oceanographic research papers Oceanographic research papers, 2021-11, Vol.177, p.103624, Article 103624
• Main Authors: Romeo, R., Giuliano Albo, P.A., Lago, S.
• Format: Article
• Language: English
• Subjects: Density; Metastable states; Pycnometer; Seawater; Thermal properties
• ISSN: 0967-0637; 1879-0119
• DOI: 10.1016/j.dsr.2021.103624

In this work, a consolidated experimental apparatus for measuring the density of liquids, such as high pressure and metastable states, based on the isochoric method, was exploited to measure thermal properties of seawater. Density of standard seawater was measured in a wide range of temperature and pressure, specifically from (261.15 to 313.15) K and up to 110 MPa. All terms contributing to the uncertainty in determining the volume and the mass of the specimen were evaluated, obtaining a relative expanded uncertainty of seawater density around 0.03% (k=2). Experimental results were fitted by using a 8-parameters function of specific volume as a function of temperature and pressure. Using the obtained expression, density, isobaric thermal expansion, and isothermal compressibility of seawater were calculated from (263.15 to 313.15) K and for pressures between (1 and 105) MPa. A comparison with the predictions obtained by the Thermodynamic Equation of Seawater - 2010 (TEOS-10) shows a general good agreement that worsens when metastable states are considered. •Density measurements of standard seawater from (261.15 to 313.15) K and up to 110 MPa.•Estimation of the relative uncertainty of seawater density.•Comparison between the experimental results and the reference equation of state.•Implementation of a 8-parameters function of specific volume to calculate density.•Calculation of seawater isobaric thermal expansion and isothermal compressibility.