Chemical Speciation of Hg(ii) with Environmental Inorganic Ligands

Kipton J. Powell, Paul L. Brown, Robert H. Byrne, Tamas Gajda, Glenn Hefter, Staffan Sjöberg, Hans Wanner

Research output: Contribution to journalArticlepeer-review

Abstract

Complex formation between Hg(ii) and the common environmental ligands Cl , OH , CO 3 2− , SO 4 2− , and PO 4 3− can have profound effects on Hg(ii) speciation in natural waters with low concentrations of organic matter. Hg(ii) is labile, so its distribution among these inorganic ligands can be estimated by numerical modelling if reliable values for the relevant stability constants are available. A summary of critically reviewed constants and related thermodynamic data is presented. Recommended values of log 10 β p,q,r ° and the associated reaction enthalpies, Δ r H m °, valid at I m = 0 mol kg −1 and 25°C, along with the equations and specific ion interaction coefficients required to calculate log 10 β p,q,r values at higher ionic strengths and other temperatures are also presented.

Under typical environmental conditions Hg(ii) speciation is dominated by the reactions Hg 2+ + 2Cl ↔ HgCl 2(aq) (log 10 β 2 ° = 14.00 ± 0.07), Hg 2+ + Cl + H 2 O ↔ Hg(OH)Cl (aq) + H + (log 10 β ° = 4.27 ± 0.35), and Hg 2+ + 2H 2 O ↔ Hg(OH) 2(aq) + 2H + (log 10 * β 2 ° = −5.98 ± 0.06).

Original languageAmerican English
JournalAustralian Journal of Chemistry
Volume57
DOIs
StatePublished - Jan 1 2004

Disciplines

  • Life Sciences

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