The effect of pressure on transition metals in seawater

Frank J Millero, Fen Huang

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The effect of pressure (P) on the activity coefficients (γiPi0) of ions (i) in seawater can be estimated from the partial molal volumes and compressibilities of the ions in water (V-0 and κ-0) and seawater (V-* and κ-*) ln(γP0)=(V-*-V-0)P/RT-0.5(κ-*-0)P2/RT where R and T have their normal meaning. One can also use the partial molal volumes and compressibilities of ions to estimate the effect of pressure (KP/K0) on ionic equilibria constants M2++X2-=MX, K = [MX]/[M2+][X2-]from the changes in the volume for the chemical reaction in seawater. δV*=V-*(MX)-V-*(M2+)-V-*(X2-), ΔV* = V-*(MX)-V-*(M2+)- V-*(X2-) using ln (K*P/K*0)=(ΔV*/RT)P-0.5 (Δκ*/RT)P2 The densities and sound speeds of a number of transition metal chlorides have been determined in 0.725m NaCl solutions (the ionic strength of average seawater, S~35) at 25°C. These results have been used to determine the partial molal volumes and compressibilities of transition metal ions (Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+). These results and our earlier measurements (Mg2+, Ca2+, Sr2+ and Ba2+) were used to develop correlations between the values in water and NaCl. These correlations were used to predict the values of other divalent ions in water and NaCl (Be2+, Pb2+, Hg2+ and Fe2+) that were difficult to directly measure. These studies allow one to make estimates of the effect of pressure on the activity coefficients of these ions in seawater and ionic equilibria in the deep oceans. The lower stability constants will result in increased concentrations of free transition metals in the deep ocean.

Original languageEnglish (US)
Pages (from-to)298-305
Number of pages8
JournalDeep-Sea Research Part I: Oceanographic Research Papers
Volume58
Issue number3
DOIs
StatePublished - Mar 2011

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transition elements
transition element
seawater
compressibility
ions
ion
sodium chloride
activity coefficient
oceans
water
chemical reactions
ionic strength
metal ions
ocean
chlorides
chemical reaction
effect
iron
calcium
chloride

Keywords

  • Complex formations
  • Compressibility
  • Pressure
  • Seawater
  • Transition metals
  • Volume

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography

Cite this

The effect of pressure on transition metals in seawater. / Millero, Frank J; Huang, Fen.

In: Deep-Sea Research Part I: Oceanographic Research Papers, Vol. 58, No. 3, 03.2011, p. 298-305.

Research output: Contribution to journalArticle

Millero, Frank J ; Huang, Fen. / The effect of pressure on transition metals in seawater. In: Deep-Sea Research Part I: Oceanographic Research Papers. 2011 ; Vol. 58, No. 3. pp. 298-305.
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