Speciation Of Thallium Research Articles

Development and evaluation of diffusive gradients in thin-films technique with a novel titanium peroxide binding gel for in situ measurement of Tl in natural waters and sediments

Speciation of thallium (Tl) controls its fate and biogeochemical behaviors. Thus, a sensitive and accurately approach for Tl monitoring is of great demand due to its ultra-low concentration and sensitivity to redox change. In this study, diffusive gradients in thin-films technique (DGT) assembled with novel titanium peroxide (TP) binding gels (TP-DGT) was developed for in situ measurement of dissolved Tl(I) and Tl(III) in waters and sediments. Laboratory test showed a linear mass accumulation of Tl(I) and Tl(III) on the TP binding gels with the deployment time from 4 to 72 h. A fascinating performance of this novel DGT was achieved in a pH range of 4–9, ionic strength range of 0.1–200 mmol L−1, and humic acid concentration of 0–30 mg L−1 with a low detection limit of 0.3 ng L−1 for Tl(I) and 0.6 ng L−1 for Tl(III). The TP binding gels own excellent stability (1–365 d) and high capacity (73.5 μg Tl disc−1) which are suitable for long-term monitoring. Field application in a river indicated that TP-DGT could work effectively, comparable to the grab sampling in waters. For the first time, the TP-DGT coupled with oxygen optode was successfully applied to map 2D distribution patterns of Tl and oxygen simultaneously in the rhizosphere of M. verticillatum L. This study confirms TP-DGT is a promising tool for routine monitoring of Tl in waters and for investigating biogeochemical processes of Tl in sediments.

Geochemical distribution and speciation of thallium in groundwater impacted by acid mine drainage (Southern China)

Thallium (Tl) commonly occurs in shallow groundwater affected by acid mine drainage (AMD); however, our knowledge of the occurrence of Tl in shallow groundwater is limited. This study observes that the shallow groundwater in an AMD-impacted area in Southern China contains an elevated Tl concentration (22 μg/L) under the oxidizing conditions and a low Tl concentration (<1 μg/L) in the reducing environment. The groundwater Tl concentration is positively correlated with oxidation-reduction potential (Eh) and negatively correlated with Cl content. The modelling results of the Tl species demonstrate that Tl+, TlSO4−, TlCl, and TlNO3 are the main forms of Tl in groundwater. Tl may precipitate as Tl(OH)3 under weakly acidic to alkaline conditions. Drill-core analysis of wells indicates that the Tl content in the vadose zone is equal to the background soil Tl content under oxidizing conditions. However, under artificial reducing conditions, the Tl content at the 3–4 m depth below the groundwater level ranges from 1.6 to 3.5 μg/g. This finding demonstrates that Tl solute in groundwater migrates into the aquifer when redox conditions change. Mn-oxides and illite in the weak permeable aquifer are the key minerals for Tl adsorption; some major sites of illite start to uptake Tl from pH 8.0. This study highlights not only the geochemical distribution of Tl in groundwater but also the influences of changes in redox conditions caused by human activities on Tl enrichment in groundwater. Enhancing our understanding of the aqueous geochemistry of Tl is of significance for the prevention and control of Tl pollution.

Dispersive micro-solid phase extraction with a magnetic nanocomposite followed by electrothermal atomic absorption measurement for the speciation of thallium

A magnetic dispersive micro-solid phase extraction procedure for the determination of the thallium content in waters is presented. The incorporation in the sample (10 mL) of a small amount of graphene-Fe3O4 composite (3.6 mg) in the presence of 10−4 mol L−1 Aliquat 336 at pH 2 results in the complete retention of both thallium(I) and thallium(III). After separation with a magnet, the micro-solid phase recovered is treated with 0.05 mL of a 0.1 mol L−1 sodium ethylenediaminetetracetate solution at pH 9, and the supernatant obtained after application of the magnet is introduced in the electrothermal atomizer of an atomic absorption spectrometer to obtain the signal corresponding to the total thallium content. For speciation, the trivalent form in a second sample aliquot is separated by means of a liquid-liquid extraction stage with chloroform and methyl trioctyl ammonium in the presence of bromide, and the signal corresponding to the monovalent form is obtained, the concentration of thallium(III) being obtained by difference. The enrichment factor is 185, which permits a detection limit as low as 0.01 μg L−1 of the analyte to be achieved. The relative standard deviation for five measurements at the 0.1 μg L−1 thallium level is below 5%. The reliability of the procedure is verified by analysing five certified reference samples for which speciation data are also given.

A new simple, highly sensitive and selective spectrofluorimetric method for the speciation of thallium at pico-trace levels in various complex matrices using N-(pyridin-2-yl)-quinoline-2-carbothioamide.

A very simple and non-extractive new spectrofluorimetric method for the determination of TlI and TlIII individually and for mixtures of both analytes at pico-trace levels using N-(pyridin-2-yl)-quinoline-2-carbothioamide (PQCTA) has been developed. PQCTA reacts in a slightly acidic (0.0025–0.05 M H2SO4) solution with TlIII in 20% ethanol and is oxidized itself to produce highly fluorescent oxidized product in aqueous solution, which has the excitation and emission wavelengths of λex = 324 nm and λem = 379 nm, respectively. The determination of TlI is based on the rapid oxidation of this ion by bromine water heating for 15 min with the concomitant formation of fluorescent TlIII-PQCTA. Fluorescence due to the sum of TlI and TlIII is measured and TlI is determined from the difference in fluorescence values. Constant and maximum fluorescence intensities were observed for the period between 2 min and 24 h. Linear calibration graphs were obtained for 0.001–600 μg L−1 of Tl, providing a detection limit of 0.16 ng L−1. The quantification limit of the reaction system was 1.6 ng L−1 and the RSD was 0–2%. A large excess of over 80 cations, anions, and complexing agents (such as chloride, phosphate, azide, tartrate, oxalate, and SCN−) do not interfere in the determination. The developed method was successfully used in the determination of thallium in several Standard Reference Materials (SRM) as well as in some environmental waters, biological fluids, soil and food samples, solutions containing both TlI and TlIII, and complex synthetic mixtures. The results of the proposed method for biological samples, vegetables, food, soil, and water analyses were found to be in excellent agreement with those obtained by ICP-OES, AAS, and ICP-MS.

Quantification of Tl (I) and Tl (III) based on microcolumn separation through ICP-MS in river sediment pore water.

Thallium (Tl) is a typical toxic element, whose biological effects and geochemical behavior are closely related with its chemical speciation in the environment. In this context, the objective of the present study was to develope an effective method for separation of Tl (I) and Tl (III) based on solid-phase extraction (SPE) using anion exchange resin AG1-X8 as a sorbent and ICP-MS measurement. In this proposed method, Tl (I) and Tl (III) could be separated by selective adsorption of Tl (III)-DTPA in the resin, while Tl (III) was eluted by the solution mixed with HCl and SO2. The validity of this method was confirmed by assays of standard solutions of Tl (I) and Tl (III), as well as with spike of contaminated samples. The present study results revealed that higher concentration of Tl (I) (245.48μg/l) and Tl (III) (20.92μg/l) had been found near the acid mine drainage (AMD) sample of sediment pore water. The results revealed that Tl (I) of 61.47μg/l and Tl (III) of 9.73μg/l were present in the river water contaminated by acid mine drainage. This thallium speciation analysis implied that the dominant Tl (I) species in the river water studied might be due to the weathering of sulfide mineral-bearing rocks, mining, and smelting activities in the studied area.

The speciation of thallium in (Tl,Sb,As)-rich pyrite

Three samples of (Tl,Sb,As)-rich pyrite from the ore deposits of the southern Apuan Alps (Tuscany, Italy) were studied through a multi-technique approach in order to constrain the speciation and incorporation mechanism of thallium in pyrite. High concentrations of Tl, Sb, and As were detected in all the studied samples through laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Average Tl contents were 1299 ppm, 1967 ppm, and 2623 ppm in samples from Sennari, Canale della Radice, and Fornovolasco, respectively. The LA-ICP-MS time-resolved down-hole ablation profiles were smooth indicating that Tl, Sb, and As are dissolved in the pyrite matrix, or occur in homogeneously distributed nanoparticles (NPs). X-ray absorption spectroscopy (XAS) data revealed that Tl, Sb, and As occurs as Tl+, Sb3+, As3+, and As−. In all the studied samples, bond distances and coordination numbers for Sb3+ and As3+ are constant, whereas Tl displays a range of coordination numbers (∼3 to ∼6), revealing the occurrence of different local environments. Moreover, no hints of features corresponding to coordination shells higher than the first were observed, suggesting an extremely disordered environment around Tl. Transmission electron microscopy (TEM) investigations revealed the presence of dislocations and As-rich “fluid” inclusions, whereas no Tl-rich NPs were observed. The study suggests that Tl+ could occur in structural defects in pyrite, lacking any long-range order. The ‘loose’ nature of Tl in pyrite favours its ready loss during the metamorphic recrystallization of pyrite and its redistribution within ore bodies and country rocks, with important implications from an economic and environmental point of view.

A modified method of separating Tl(I) and Tl(III) in aqueous samples using solid phase extraction

In spite of the development of new measurement techniques in recent years, the rapid and accurate speciation of thallium in environmental aqueous samples remains a challenge. In this context, a novel method of solid phase extraction (SPE), involving the anion exchange resin AG1-X8, is proposed to separate Tl(I) and Tl(III). In the presence of diethylene triamine pentacetate acid (DTPA), Tl(III) and Tl(I) can be separated by selective adsorption of Tl(III)-DTPA onto the resin, Tl(III) is then eluted by a solution of HCl with SO2. The validity of this method was confirmed by assays of standard solutions of Tl(I) and Tl(III). The proposed method is shown to have an outstanding performance even in solutions with a high ratio of Tl(I)/Tl(III), and can be applied to aqueous samples with a high concentration of other electrolytes, which could interfere with the measurement. Portable equipment and reagents make it possible to use the proposed method routinely in the field.

Combination of Solid Phase Extraction With Dispersive Liquid-liquid Microextraction for Speciation of Thallium in Water Sample by Electrothermal Vaporization ICP-MS

Combination of Solid Phase Extraction With Dispersive Liquid-liquid Microextraction for Speciation of Thallium in Water Sample by Electrothermal Vaporization ICP-MS

Influence of environmental and anthropogenic parameters on thallium oxidation state in natural waters

The abandoned mining area of Valdicastello Carducci (Tuscany, Italy) is characterized by the massive presence of thallium in the acid mine drainages and in the valley stream crossing the region. We previously found that Tl(III), generally considered the less stable oxidation state of thallium, is present both in the stream and in tap water distributed in the area, whereas acid mine drainages only contain Tl(I). These findings posed some concern related to the reactivity and dispersion of this toxic element in the environment. Since the valence state of thallium determines its toxicity, distribution and mobility, the study of thallium redox speciation appears crucial to understand its environmental behaviour.In this work, water samples collected from the mine drainages and the contaminated stream were adopted as model to study the distribution of aqueous Tl(I)/Tl(III) as a function of light exposure and solution properties and composition. The influence of three light sources and organic acids was evaluated. Thallium speciation was also assessed in tap water after treatment with common oxidizing agents, and in the rust crust collected from the public waterworks.

Solid phase extraction with titanium dioxide nanofibers combined with dispersive liquid-liquid microextraction for speciation of thallium prior to electrothermal vaporization ICP-MS

The authors describe a method for speciation of thallium that is based on solid phase extraction (SPE) combined with dispersive liquid-liquid microextraction (DLLME) prior to electrothermal vaporization ICP-MS determination. The method is shown to be applicable to the determination of total, suspended, soluble, organic and inorganic Tl, and of Tl(I) and Tl(III) in tea leaves and tea infusion. The SPE step involves the use of titanium dioxide nanofibers for preconcentration of the Tl analytes and simultaneous removal of the matrix components such as polyphenols, soluble sugars, catechin, caffeine and tea pigments. Following elution of Tl with dilute HNO3, the eluate was further preconcentrated and separation by DLLME. After optimization of the method, it has a detection limits of 0.015 pg mL−1 for Tl(I) and of 0.020 pg mL−1 for Tl(III), with relative standard deviations of 6.5% and 7.3% (at 0.10 ng mL−1; for n = 9), respectively. The technique has an enrichment factor of 450 and is highly selective. It was successfully applied to the speciation and distribution of thallium in tea leaves and tea infusions. A certified reference material of tea leaves was analyzed by this method, and the obtained values were in good agreement with the certified values.

Preconcentration and speciation of thallium by ferrofluid based dispersive solid phase extraction and flame atomic absorption spectrometry

A dispersive solid phase extraction method based on ferrofluid has been proposed for the separation and preconcentration of thallium (I) before its determination by flame atomic absorption spectrometry. The ferrofluid was rapidly injected into the aqueous sample containing the thallium (I) and dibenzo-18-crown-6 (DB18C6) as the chelating agent with a syringe. The separation of the sorbent from the aqueous phase was achieved by the application of an external magnet. The main factors affecting the extraction of thallium (I) were investigated and optimized. Total thallium was determined after the reduction of Tl(III) to Tl(I) by hydroxylamine hydrochloride. Under the optimized conditions with a sample volume of 150.0mL, the detection limit (based on 3Sb/m) and the enhancement factor were found to be 0.85μgL–1 and 298, respectively. The relative standard deviation at 50μgL–1 concentration level of Tl(I) was 3.2%. The method was successfully applied to the determination of thallium species in water and waste water samples as well as total thallium in nail, hair, cabbage and iron ore samples. The validity of the method was checked through the recovery experiments besides the analysis of a certified reference material.

Stability of Tl(III) in the context of speciation analysis of thallium in plants.

The paper presents both "good" and "bad" results obtained during speciation analysis of thallium in plant tissues of a hyperaccumulator of this metal. The object was white mustard - Sinapis alba L. In this plant there were found traces of trivalent thallium. The crucial point of this study (especially in the case of so unstable thallium form as Tl(III)) was to prove that the presence of Tl(III) was not caused by the procedure of sample preparation itself, and that the whole analytical method provides reliable results. Choice of the method for conservation of the initial speciation, extraction with the highest efficiency and proving the correctness of the obtained data were the most difficult parts of the presented study. It was found that: both freezing and drying cause significant changes in the speciation of thallium; quantitative analysis could be performed only with fresh tissues of mustard plants; only short-term storage of an extract from fresh plant tissues is possible; the methodology is not the source of thallium (III); only the presence of DTPA can greatly limit the reduction of TI(III) to TI(I) (up to 1-3%); the UV irradiation results in disintegration of TI(III)DTPA in the presence of plant matrix (reduction up to 90%).

Thallium Speciation and Extractability in a Thallium- and Arsenic-Rich Soil Developed from Mineralized Carbonate Rock

We investigated the speciation and extractability of Tl in soil developed from mineralized carbonate rock. Total Tl concentrations in topsoil (0-20 cm) of 100-1000 mg/kg are observed in the most affected area, subsoil concentrations of up to 6000 mg/kg Tl in soil horizons containing weathered ore fragments. Using synchrotron-based microfocused X-ray fluorescence spectrometry (μ-XRF) and X-ray absorption spectroscopy (μ-XAS) at the Tl L3-edge, partly Tl(I)-substituted jarosite and avicennite (Tl2O3) were identified as Tl-bearing secondary minerals formed by the weathering of a Tl-As-Fe-sulfide mineralization hosted in the carbonate rock from which the soil developed. Further evidence was found for the sequestration of Tl(III) into Mn-oxides and the uptake of Tl(I) by illite. Quantification of the fractions of Tl(III), Tl(I)-jarosite and Tl(I)-illite in bulk samples based on XAS indicated that Tl(I) uptake by illite was the dominant retention mechanism in topsoil materials. Oxidative Tl(III)uptake into Mn-oxides was less relevant, probably because the Tl loadings of the soil exceeded the capacity of this uptake mechanism. The concentrations of Tl in 10 mM CaCl2-extracts increased with increasing soil Tl contents and decreasing soil pH, but did not exhibit drastic variations as a function of Tl speciation. With respect to Tl in contaminated soils, this study provides first direct spectroscopic evidence for Tl(I) uptake by illite and indicates the need for further studies on the sorption of Tl to clay minerals and Mn-oxides and its impact on Tl solubility in soils.

Assessing the fate and toxicity of Thallium I and Thallium III to three aquatic organisms

Thallium has been shown to significantly increase in both water and aquatic biota after exposure to metal mine effluent, however, there is a lack of knowledge as to its fate and effect in the aquatic environment. The objectives of this project were to assess (1) fate of thallium by conducting speciation analysis and determining the influence of water quality on toxicity and (2) effects of thallium (I) and (III) on three aquatic species; the algae, Pseudokirchneriella subcapitata, the invertebrate Ceriodaphnia dubia and the vertebrate Pimephales promelas.Speciation analysis proved challenging with poor recovery of thallium (I), however analysis with solutions >125μg/L revealed that over a 7-d period, recovery of thallium (III) was less than 15%, suggesting that the majority of thallium (III) was converted to Thallium (I). It was only in fresh solutions where recovery of Thallium (III) was greater than 80%.The lowest IC25s generated during our effects assessment for both Thallium (I) and (III) were more than 10-fold greater than the highest concentration recorded in receiving environments (8μg/L) and more than 100-fold greater than the current guideline (0.8μg/L).To assess the influence of water quality on thallium toxicity, the concentrations of both potassium and calcium were reduced in dilution water. When potassium was reduced for both C. dubia and P. subcapitata tests, the lowest IC25 generated was 5-fold higher than the current guideline, but within the range of concentrations reported in receiving environments for both Thallium (I) and (III). When calcium was reduced in dilution water, toxicity only increased in the Tl (III) tests with C. dubia; the IC25 for Tl(III), similar to the exposures conducted with reduced potassium, was within the range of total thallium concentrations reported in the receiving environment.Without an accurate, repeatable method to assess thallium speciation at low concentrations it is not possible to draw any firm conclusions as to whether the IC25s for Tl (III) are relevant to concentrations present in receiving environments. Based on the results of our study we recommend that any test, to determine Thallium (III) toxicity, use fresh solutions, made daily, to get good recovery and accurate toxicity results. The results generated in our effects and exposure assessment would indicate that the current guideline of 0.8μg/L is protective. Special attention should be placed on the concentration of potassium in receiving environments when estimating thallium toxicity.

Arsenic, Antimony, Chromium, and Thallium Speciation in Water and Sediment Samples with the LC-ICP-MS Technique.

Chemical speciation is a very important subject in the environmental protection, toxicology, and chemical analytics due to the fact that toxicity, availability, and reactivity of trace elements depend on the chemical forms in which these elements occur. Research on low analyte levels, particularly in complex matrix samples, requires more and more advanced and sophisticated analytical methods and techniques. The latest trends in this field concern the so-called hyphenated techniques. Arsenic, antimony, chromium, and (underestimated) thallium attract the closest attention of toxicologists and analysts. The properties of those elements depend on the oxidation state in which they occur. The aim of the following paper is to answer the question why the speciation analytics is so important. The paper also provides numerous examples of the hyphenated technique usage (e.g., the LC-ICP-MS application in the speciation analysis of chromium, antimony, arsenic, or thallium in water and bottom sediment samples). An important issue addressed is the preparation of environmental samples for speciation analysis.

Indirect Speciation Analysis of Thallium in Plant Extracts by Anodic Stripping Voltammetry

AbstractA sensitive voltammetric method (DPASV) was developed for the determination of Tl(I) and Tl(III) in plant extracts. To limit the influence of the organic matrix on the measurements, UV irradiation and addition of Amberlite XAD‐7 resin was studied. The application of 0.5 g of the resin allowed defining thallium speciation in 10.0 mL of a solution containing 0.20 mL of Sinapis alba extract. The quantification limit of 0.5 ng mL−1 Tl(I) was found for only 10 min of preconcentration, and is low enough to allow dilution of the sample before thallium determination. The procedure was validated using the recovery study and intermethod comparison with HPLC ICP MS.

Thallium speciation in plant tissues—Tl(III) found in Sinapis alba L. grown in soil polluted with tailing sediment containing thallium minerals

Besides the dominant species in plants—Tl(I), noticeable amounts of Tl(III) (about 10% of total Tl content) were found in extracts of plants cultivated in the presence of tailing sediments, which are the main source of anthropogenic thallium already present in the environment. It is an important step of gaining knowledge about the detoxification mechanisms developed by Sinapis alba. This plant species is highly tolerant to Tl and it is able to cumulate high amounts of Tl and transport it into the above-ground organs. For more adequate estimation of accumulating abilities of S. alba, the elements’ bioavailability was taken into consideration. The obtained bioconcentration factors of Cd (AF=0.6) and Zn (AF=1–2) were significantly lower than of Tl (AF=100–200). The biomass production was similar to the biomass of control cultivation. The results were based on ICP MS measurements of total elements’ content and HPLC ICP MS for speciation analysis. The quality of obtained results was evaluated based on the intermethod comparison with voltammetry as a reference method. Comparison of data obtained using ICP MS and electrochemical methods (after a proper chemical treatment) was also used for indication of Tl(III) presence and for proving that Tl(I) was not transferred into Tl(III) during analytical procedures.

Selective preconcentration of thallium species as chloro and iodo complexes on Chromosorb 105 resin prior to electrothermal atomic absorption spectrometry

A selective preconcentration method was described for the determination of inorganic thallium species by electrothermal atomic absorption spectrometry (ETAAS). Thallium(III) and thallium(I) as chloro and iodo complexes were selectively retained by a column containing 0.5g of Chromosorb 105 resin and quantitatively eluted by 10mL of pure acetone. The calibration graph was linear with a correlation coefficient of 0.997 at levels near the detection limit and up to at least 0.8μgL−1. The detection limits for the determination of total thallium and thallium(III) employing the proposed method by ETAAS were estimated as three values of the standard deviations, 0.050μgL−1 and 0.034μgL−1, respectively. Verification of the accuracy was carried out by the analysis of standard reference materials (GBW 07402 soil, NIST 2710 Montana soil, GBW 07309 and GBW 07310 stream sediments). The relative errors were found to be in the range of −7.7% to +4.8%. The relative standard deviations were generally found to be below 10%. The effect of potential interfering ions on the determination was studied. The proposed method was successfully applied to the determination of total thallium in five different brand cements, soils around two cement plants and metallic zinc samples. The speciation of thallium(I) and thallium(III) was applied to synthetic solutions.

Determination of thallium forms in plant extracts by anion exchange chromatography with inductively coupled plasma mass spectrometry detection (IC-ICP-MS)

The speciation of thallium was investigated in the Indian mustard plant (Sinapis alba L.), hydroponically cultivated and in moss (Entondon schreberi) used as a bioindicator. The separation of thallium species was done using anion exchange chromatography coupled with on-line ICP-MS detection with 100 mmol L−1 ammonium acetate containing 5 mmol L−1 DTPA as a mobile phase. The study indicated that Tl(I) is the dominating form in plant extracts; Tl(III) was not detected. Three species of Tl were found in the leaves, two of them remained unidentified. Additionally, the fractionation study of Tl in organs of the Indian mustard plant using water, ammonium acetate containing DTPA and sodium dodecyl sulfate solutions was performed. The highest leaching efficiency was reached using an ammonium acetate/DTPA solution. Next, the efficiency of Tl transport from roots to stems and leaves and the accumulation factors were estimated. 80% of uptaken Tl was found in above-ground plant organs.

Distribution of natural and anthropogenic thallium in the soils in an industrial pyrite slag disposing area

The total concentrations combined with the chemical speciation of thallium (Tl) were examined in order to track the distribution of natural and anthropogenic Tl in the soils in an industrial pyrite slag disposing area. Their geochemical behaviors in the soils were further discussed. Soil samples were collected from three soil profiles adjacent to a large open-disposed pile of industrial Tl-rich pyrite slag, and from one soil profile in the background area. The results show that the soil contamination with Tl derived from slag (slag-Tl) is generally limited; slag-Tl was mainly accumulated in the upper part (<16.5 cm) of the vicinal soils of the slag pile and shows large variation in concentration among different sampling sites. Basically, the soils surrounding the slag pile within 5 m are more Tl-contaminated than those under the slag pile and those far away from the slag pile. In respect of the concentrations of total Tl, the deeper soils of the studied profiles seem to be uncontaminated. However, the percentages of Tl in the easily reducible fraction indicate that these soils have been actually contaminated by slag-Tl. Natural Tl and anthropogenic Tl are distributed differently among the soil components in the studied soils. Natural Tl in the background soils is predominantly hosted in the residual fraction (∼98%), while anthropogenic Tl was significantly incorporated into the more labile fractions of the soil (up to ∼80%), especially in the acid-extractable fractions and easily reducible fraction (up to ∼30% and ∼45%, respectively). Detailed analysis of speciation data of Tl suggests that despite being predominantly controlled by the degree of Tl pollution, the distribution of slag-Tl in the soils can be further affected by the general differences in soil properties. In this study, the order for preferential immobilization of anthropogenic Tl among major soil components can be roughly summarized as: Tl(III) carbonates and hydroxides>Mn oxide–hydroxides>Fe oxide–hydroxides>adsorption sites on the surface of soil, while the order can be significantly mediated by the pH conditions in the soils. The correlations between the fractions of Tl in the slag and in the soils indicate that the anthropogenic Tl in the soils in the studied slag disposing area should be mainly derived from the dissolved slag-Tl that was leached by rainwater rather than from the washed-out particles of slag.