Computer Science
Scientific paper
May 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007gecoa..71.2170s&link_type=abstract
Geochimica et Cosmochimica Acta, Volume 71, Issue 9, p. 2170-2189.
Computer Science
24
Scientific paper
Equilibrium stable isotope fractionations of mercury and thallium are estimated for molecules, atoms and ions using first-principles vibrational frequency and electronic structure calculations. These calculations suggest that isotopic variation in nuclear volume is the dominant cause of equilibrium fractionation, driving 205Tl/203Tl and 202Hg/198Hg fractionations of up to 3‰ at room temperature. Mass-dependent fractionations are smaller, ca. 0.5 1‰ for the same isotopes. Both fractionation mechanisms tend to enrich the neutron-rich isotopes in oxidized mercury- and thallium-bearing phases (Tl3+ and Hg2+) relative to reduced phases (Tl+ and Hg0). Among Hg2+-bearing species, inorganic molecules and complexes like HgCl2, HgCl42- and Hg(HO)62+ will have higher 202Hg/198Hg than coexisting methylmercury species, suggesting a possible application of Hg-isotope measurements to understanding mercury methylation and increasing methylmercury concentrations at the top of the food chain. Estimated 205Tl/203Tl fractionation between Tl(HO)63+ and Tl(HO)3+ is in reasonable agreement with the fractionations previously observed between seawater and Fe Mn crusts, supporting an equilibrium-like reduction/oxidation fractionation mechanism. More generally, nuclear-volume isotope fractionation will concentrate larger (heavier) nuclei in species where the electron density at the nucleus is small—due to lack of s-electrons (e.g., Hg2+—[Xe]4f145d106s0 vs. Hg0—[Xe]4f145d106s2) or enhanced s-electron screening by extra p, d, or f electrons (e.g., Tl0—[Xe]4f145d106s26p1 vs. Tl+—[Xe]4f145d106s26p0). Nuclear-volume fractionations become much smaller for lighter elements, declining from ˜1‰/amu for thallium and mercury to ˜0.2‰/amu for ruthenium and ˜0.02‰/amu for sulfur.
No associations
LandOfFree
Role of nuclear volume in driving equilibrium stable isotope fractionation of mercury, thallium, and other very heavy elements does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Role of nuclear volume in driving equilibrium stable isotope fractionation of mercury, thallium, and other very heavy elements, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Role of nuclear volume in driving equilibrium stable isotope fractionation of mercury, thallium, and other very heavy elements will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-767007