Revised Hydrolysis Constants for Thallium(I) and Thallium(III) and the Environmental Implications

Abstract

The hydrolysis constants for Tl(I) and Tl(III) have been determined by combining potentiometric measurement with the PKAS computer program. The log hydrolysis constants (Kh i ) for Tl

Sediment–water interactions of thallium under simulated estuarine conditions

“…doi:10. 1016/j.gca.2010.09.004 at least 200 lg L À1 because the s-electrons display a low propensity to be displaced or bound covalently (Lin and Nriagu, 1997;Kaplan and Mattigod, 1998;Gao et al, 2007). In both oxygenated and anoxic systems, Tl(I) is predicted to exist predominantly as the free ion in fresh waters and, additionally, as TlCl 0 in saline environments.…”

“…In some cases, reported concentrations of Tl(III) exceed those of Tl(I), although Cheam (2000) suggests that the contribution of the former may have been significantly overestimated because of sample acidification and the nature of the standards employed to validate the method. Inorganic equilibrium calculations predict that the higher oxidation state exists mainly as the sparingly soluble and relatively unreactive Tl(OH) 3 0 , and as chloro and hydroxy complexes (Lin and Nriagu, 1997). Covalent Tl complexes are more stable in the trivalent form and experimental evidence suggests that dimethylthallium, Tl(CH 3 ) 2 + , may also be produced under anaerobic conditions (Thayer, 2002).…”

“…Equilibrium complexation constants for Tl(I) used in the speciation calculations(Lin and Nriagu, 1997;Laforte et al, 2005 and references therein).…”

Thallium diagenesis in lacustrine sediments

“…Only a few studies have been carried out in the water column of marine (Batley and Florence, 1975;Flegal and Patterson, 1985;Flegal et al, 1986;Flegal et al, 1989) and freshwater (Lin and Nriagu, 1998a;Nriagu, 1999a, 1999b;Ralph and Twiss, 2002;Twining et al, 2003;Twiss et al, 2003;Twiss et al, 2004) systems; these studies yielded information on Tl distribution and speciation in the water column and on its uptake and redox transformation by phytoplankton.…”

Photochemical reaction of Tl in aqueous solution and its environmental significance

“…Locally about 1000 people were affected by endemic Tl poisoning during the 1960s-1970s (Zhou and mals, and is readily transferred into human body through the food chain. However, Tl(III) usually exists in aqueous solution in the form of Tl(OH) 3 , with a solubility product K sp = 10 -45.2 , among the least soluble metal hydroxides (Lin and Nriagu, 1998), so Tl(III) is easy to be deposited or be adsorbed. It is commonly considered that thallium contamination in the environment is controlled mainly by soluble Tl(I).…”