Chemical Speciation of Hg(ii) with Environmental Inorganic Ligands

Authors

Kipton J. Powell, University of Canterbury
Paul L. Brown, Monash University
Robert H. Byrne, University of South FloridaFollow
Tamas Gajda, A. József University
Glenn Hefter, Murdoch University
Staffan Sjöberg, Umeå University
Hans Wanner, Swiss Federal Nuclear Safety Inspectorate, 5232 Villigen, Switzerland.

Document Type

Article

Publication Date

2004

Digital Object Identifier (DOI)

https://doi.org/10.1071/CH04063

Abstract

Complex formation between Hg(ii) and the common environmental ligands Cl⁻, OH⁻, CO₃²⁻, SO₄²⁻, and PO₄³⁻ 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 log₁₀β_p,q,r° and the associated reaction enthalpies, Δ_rH_m°, valid at I_m = 0 mol kg⁻¹ and 25°C, along with the equations and specific ion interaction coefficients required to calculate log₁₀β_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 Hg²⁺ + 2Cl⁻ ↔ HgCl_2(aq) (log₁₀β₂° = 14.00 ± 0.07), Hg²⁺ + Cl⁻ + H₂O ↔ Hg(OH)Cl_(aq) + H⁺ (log₁₀β° = 4.27 ± 0.35), and Hg²⁺ + 2H₂O ↔ Hg(OH)_2(aq) + 2H⁺ (log₁₀*β₂° = −5.98 ± 0.06).

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Australian Journal of Chemistry, v. 57, issue 10, p. 993-1000

Scholar Commons Citation

Powell, Kipton J.; Brown, Paul L.; Byrne, Robert H.; Gajda, Tamas; Hefter, Glenn; Sjöberg, Staffan; and Wanner, Hans, "Chemical Speciation of Hg(ii) with Environmental Inorganic Ligands" (2004). Marine Science Faculty Publications. 1632.
https://digitalcommons.usf.edu/msc_facpub/1632