Isotopic Tracing of Thallium Contamination in Soils Affected by Emissions from Coal-Fired Power Plants

Abstract

Here, for the first time, we report the thallium (Tl) isotope record in moderately contaminated soils with contrasting land management (forest and meadow soils), which have been affected by emissions from coal-fired power plants. Our findings clearly demonstrate that Tl of anthropogenic (high-temperature) origin with light isotope composition was deposited onto the studied soils, where heavier Tl (ε(205)Tl ∼ -1) naturally occurs. The results show a positive linear relationship (R(2) = 0.71) between 1/Tl and the isotope record, as determined for all the soils and bedrocks, also indicative of binary Tl mixing between two dominant reservoirs. We also identified significant Tl isotope variations within the products from coal combustion and thermo-desorption experiments with local Tl-rich coal pyrite. Bottom ash exhibited the heaviest Tl isotope composition (ε(205)Tl ∼ 0), followed by fly ash (ε(205)Tl between -2.5 and -2.8) and volatile Tl fractions (ε(205)Tl between -6.2 and -10.3), suggesting partial Tl isotope fractionations. Despite the evident role of soil processes in the isotope redistributions, we demonstrate that Tl contamination can be traced in soils and propose that the isotope data represent a possible tool to aid our understanding of postdepositional Tl dynamics in surface environments for the future.

Thallium concentration and thallium isotope composition of lateritic terrains

“…This application relies on the existence and preservation of an 'anthropogenic' Tl stable isotope signature. However, the potential secondary Tl stable isotope effects from lithospheric and pedospheric processes remain poorly defined and require further investigation to better aid reliable tracing of industrial Tl emissions (Kersten et al, 2014;Voegelin et al, 2015;Vaněk et al, 2016). Potential sources of fractionation include riverine transport processes and continental weathering: the latter providing the impetus for the current study.…”

“…Surface soil Tl concentrations have been shown to depend not only on substrate lithology but also on the presence of anthropogenic Tl contamination, for example from cement plants (e.g. Jacobson et al, 2005;Pavlíčková, 2006;Vaněk et al, 2009;Kersten et al, 2014;Vaněk et al, 2016;Vaněk et al, 2018). Studies of heavily contaminated soils (hundreds to thousands of µg/g Tl) have…”

“…Furthermore, in soils with lower Tl concentrations (few tens of µg/g Tl) the Tl adsorption appears dominated by Mn-oxides, with negligible adsorption onto Fe(III) oxides such as goethite (Vaněk et al, 2009;Vaněk et al, 2011;Voegelin et al, 2015;Vaněk et al, 2016).…”

Monitoring Impacts of Urbanisation and Industrialisation on Air Quality in the Anthropocene Using Urban Pond Sediments

“…FIGURE 6 | Historical fuel consumption trends for Chongqing (Fumin and Zesheng, 2016) showing coal, natural gas and oil consumption from 1949 to 2013, plotted alongside pollution flux data from SKP (1960SKP ( -2015. SIRM, a proxy for PM 10 and PM 2.5 pollution (Speak et al, 2012;Wang et al, 2017); SCPs, unambiguous indicator of fossil fuel combustion (Rose, 2015); Tl, a tracer for coal emissions (Vaněk et al, 2016) and smelting (Karbowska, 2016); and Cd, a tracer for industry, smelting and coal combustion (Gao et al, 2013;Shi et al, 2018) are presented. Tl and Cd were selected as metals representative of anthropogenic enrichment (Table 3).…”

Epithermal Origin and Environmental Evolution of Iron-Hosted Thallium and Kerogen Deposits: The Lodares Area Case (Soria, Spain)

“…The high toxicity of Tl and its presence in coals and carbonaceous sediments had prompted studies on its bioavailability and geochemical cycling in smelting ashes, soils, coals, etc. [8][9][10][11][12][13][14]. The Lodares (Soria, Spain) area deposits and other similar carbonate rock-hosted epithermal deposits could be interesting polymetallic sources, e.g., the Jas Roux deposit (France) with Tl phases hosted in Triassic calcareous rocks [15], the Alshar Au-As-Sb-Tl deposit (Macedonia) developed as a mineralized breccia at the contact of volcanic rocks with dolomites, jasperoid beds in the carbonate rocks, and vein-disseminated zones in dolomites and Tertiary volcanic rocks [16], or the case of Agdarreh (Iran) [17] which includes: (1) pre-ore decalcification with dolomite dissolution re-precipitation, (2) a first-stage silicification process associated with pyrite, (3) a second-stage silicification linked with precipitation of galena and, Hg-Tl-Sb-As sulfides, (4) late-stages of cinnabar and baryte in pockets; (5) oxide ore stage and carbonate alteration, e.g., complex Mn-Fe-rich oxy-hydroxides, arsenates, sulfates in residual leached rock and infill of karstic cavities.…”