Experimental study of mass-independence of Hg isotope fractionation during photodecomposition of dissolved methylmercury
- 23 February 2010
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of Analytical Atomic Spectrometry
- Vol. 25 (7), 950-956
- https://doi.org/10.1039/b926650j
Abstract
Experiments modelling photolytic decomposition of methylmercury chloride in aqueous solutions of different chemical composition have been performed. Ion-exchange chromatographic separation using Chelex® 100 resin was used in order to separate methylmercury from inorganic mercury prior to the isotope ratio measurements by solution nebulization multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The performance of the chromatographic separation has been evaluated in terms of recovery of both methylmercury and inorganic Hg using synthetic solutions. Both mass-dependent and mass-independent fractionation of Hg isotopes concomitant with the decomposition process have been observed. Mass-independent Hg isotope fractionation (MIF) resulted in selective enrichment of 199Hg and 201Hg relative to the other isotopes in the methylmercury molecules and has been attributed to the magnetic isotope effect. The highest extent of MIF of Hg isotopes, expressed as Δ199Hg and Δ201Hg values, has been observed in acidified solution with low concentration of total dissolved solids (TDS). Progressive decrease in Δ199Hg and Δ201Hg values in acidified solution with higher concentration of TDS, alkaline solutions of both low and high concentration of TDS, and in a solution of ascorbic acid has been attributed to suppression of the radical pair reaction mechanism, responsible for the occurrence of the magnetic isotope effect, by substances acting as radical scavengers, such as OH − or ascorbic acid. The data obtained in this study demonstrate the significance of spin chemistry effects in the isotope fractionation of mercury.Keywords
This publication has 42 references indexed in Scilit:
- Evidence for mass-independent and mass-dependent fractionation of the stable isotopes of mercury by natural processes in aquatic ecosystemsApplied Geochemistry, 2008
- Anion-Exchange Chromatographic Separation of Hg for Isotope Ratio Measurements by Multicollector ICPMSAnalytical Chemistry, 2008
- Mercury isotope fractionation during volatilization of Hg(0) from solution into the gas phaseJournal of Analytical Atomic Spectrometry, 2007
- Production of artifact methylmercury during the analysis of certified reference sediments: Use of ionic exchange in the sample treatment step to minimise the problemAnalytica Chimica Acta, 2007
- Mercury isotope fractionation in fossil hydrothermal systemsGeology, 2005
- A consistent set of nuclear rms charge radii: properties of the radius surface R(N,Z)Atomic Data and Nuclear Data Tables, 2004
- Magnetic Isotope Effect: Nuclear Spin Control of Chemical ReactionsThe Journal of Physical Chemistry A, 2001
- DEGRADATION OF QUINOLINE BY WET OXIDATION— KINETIC ASPECTS AND REACTION MECHANISMSWater Research, 1998
- Critical Review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (⋅OH/⋅O− in Aqueous SolutionJournal of Physical and Chemical Reference Data, 1988
- Pulse radiolysis of mercuric oxide in neutral aqueous solutionsThe Journal of Physical Chemistry, 1975