Behavior Of Tl Research Articles

Thallium isotopic fractionation in soils from a historic Hg[sbnd]Tl mining area: New insights on thallium geochemistry

Thallium (Tl), a highly toxic heavy metal, which may pose significant environmental threats due to extensive discharge from anthropogenic activities. It is crucial to understand geochemical behavior of Tl in soils for initiating proper measures for Tl pollution control. For this purpose, transport behavior of Tl and its dominant factors in soils collected from a typically Tl-enriched depth profile, surrounding a historical tailing dump near an independent HgTl mine area in China, were investigated by using Tl isotope compositions. Results showed that an overall enrichment of Tl (48.68–375.21 mg/kg) was accompanied with As elevation (135.00–619.00 mg/kg) in the whole depth profile, and Tl and As exhibited co-migration behavior with Fe, S, K, and Rb. Geochemical fractionation of Tl unveiled by sequential extraction further indicated that Mn-/Fe-bearing minerals and clay minerals act as main hosts of Tl in the studied soils. Thallium isotopic composition and its fractionation pattern further revealed that the major contributors to high Tl levels in the depth profile were tailing and lorandite minerals, with mean contribution rate of 51.99% and 42.47%, respectively. These findings facilitate the understanding of Tl transport behavior in highly contaminated environment, providing valuable insights for developing new technologies in mining waste treatment and historical mine reclamation.

Surface complexation adsorption of Tl(III) by Fe and Mn (hydr)oxides

Thallium(III) (Tl(III)) is mobile in acidic environments and under ligand complexation, posing a potential threat to the environment and human health. The adsorption of Tl(III) on manganese and iron (hydr)oxides will affect its environmental mobility and engineering removal efficiency. However, the adsorption behavior and interfacial reaction mechanism of Tl(III) remain largely unknown. This study is the first to elucidate the surface complexation mechanism of Tl(III) on Fe/Mn (hydr)oxides and to investigate the adsorption behavior of Tl(III) under the influence of typical environmental ligands. Deprotonation of surface hydroxyl groups contributes to the increase in adsorption capacity for Tl(III) (δ-MnO2, 1619.93 mg g−1; α-FeOOH, 48.25 mg g−1; and α-Fe2O3, 58.66 mg g−1 from Langmuir thermodynamic fitting). Surface complexation modeling reveals tridentate complexation of Tl(III) on birnessite and monodentate complexation on iron (hydr)oxides. The anionic ligand strongly inhibits the adsorption of Tl(III) (up to 16.0 %–40.0 %) by complexing with Tl(III) and occupying the adsorption sites. In addition, HA also reduces the adsorption of Tl(III) by 8.2 %–23.2 % by exacerbating the aggregation and surface coating of the adsorbent particles. New insights into the binding mechanism of Tl(III) on Fe/Mn oxides can help to guide the development of efficient Tl(III) removal adsorbents.

Applying thallium isotopic compositions as novel and sensitive proxy for Tl(I)/Tl(III) transformation and source apportionment

Thallium is a rare metal known for its highly toxic nature. Recent research has indicated that the precise determination of Tl isotopic compositions using Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP MS) provides new opportunities for understanding Tl geochemical behavior. While isotopic fractionation of Tl derived from anthropogenic activities (e.g., mining, smelting) have been reported, there is limited information regarding Tl influenced by both natural weathering processes and anthropogenic origins. Herein, we investigated, for the first time, the Tl isotopic compositions in soils across a representative Tl-rich depth profile from the Lanmuchang (LMC) quicksilver mine (southwest China) in the low-temperature metallogenesis zone. The results showed significant variations in Tl isotope signatures (ε205Tl) among different soil layers, ranging from −0.23 to 3.79, with heavier isotope-205Tl enrichment observed in the bottom layers of the profile (ε205Tl = 2.18–3.79). This enrichment of 205Tl was not solely correlated with the degree of soil weathering but was also partially associated with oxidation of Tl(I) by Fe (hydr)oxide minerals. Quantitative calculation using ε205Tl vs. 1/Tl data further indicated that the Tl enrichment across the soil depth profile was predominantly derived from anthropogenic origins. All these findings highlight that the robustness and reliability of Tl isotopes as a proxy for identifying both anthropogenic and geogenic sources, as well as tracing chemical alterations and redox-controlled mineralogical processes of Tl in soils. The nascent application of Tl isotopes herein not only offers valuable insights into the behavior of Tl in surface environments, but also establishes a framework for source apportionment in soils under similar circumstances.

Dynamic retention of thallium(I) on humic acid: Novel insights into the heterogeneous complexation ability and responsiveness

Widely distributed soil humic acid (HA) would significantly affect the environmental migration behavior of Tl(I), but a quantitative and mechanistic understanding of the dynamic Tl(I) retention process on HA is limited. A unified kinetic model was established by coupling the humic ion-binding model with a stirred-flow kinetic model, which quantified the complexation constants and responsiveness coefficients during dynamic Tl(I)-HA complexation. Furthermore, the heterogeneous complexation mechanism of HA and Tl(I) was revealed by batch adsorption experiments, stirred-flow migration experiments, and 2D-FTIR-COS analysis. An increase in pH significantly improved the responsiveness of HA organic binding sites, promoting Tl(I) dynamic retention. Monodentate carboxyl groups induced rapid Tl(I) complexation (kd = 1.9 min−1) in strongly acidic environments. Under weakly acidic conditions, Tl(I) retention on HA was mainly attributed to the synergistic complexation effect of carboxyl and amide groups. Among the groups, multidentate carboxyl-phenolic hydroxyl sites could achieve sustained Tl(I) retention due to their stable complexing properties (logK = 4.48∼7.46) and slow response (kd = 1.1 × 10−3 min−1). These findings are crucial for a comprehensive understanding of the environmental interactions of Tl(I) with humic substances in swamp environments.

Thallium adsorption on three iron (hydr)oxides and Tl isotopic fractionation induced by adsorption on ferrihydrite

Thallium (Tl) is an extraordinarily toxic metal, which is usually present with Tl(I) and highly mobile in aquatic environment. Limited knowledge is available on the adsorption and isotopic variations of Tl(I) to Fe-(hydr)oxides. Herein, the adsorption behavior and mechanism of Tl(I) on representative Fe-(hydr)oxides, i.e. goethite, hematite, and ferrihydrite, were comparatively investigated kineticly and isothermally, additional to crystal structure modelling and Tl isotope composition (205Tl/203Tl). The results showed that ferrihydrite exhibited overall higher Tl(I) adsorption capacity (1.11–10.86 mg/kg) than goethite (0.21–1.83 mg/kg) and hematite (0.14–2.35 mg/kg), and adsorption by the three prevalent Fe-minerals presented strong pH and ionic strength dependence. The magnitude of Tl isotopic fractionation during Tl(I) adsorption to ferrihydrite (αsolid-solution ≈ 1.00022–1.00037) was smaller than previously observed fractionation between Mn oxides and aqueous Tl(I) (αsolid-solution ≈ 1.0002–1.0015). The notable difference is likely that whether oxidation of Tl(I) occurred during Tl adsorption to the mineral surfaces. This study found a small but detectable Tl isotopic fractionation during Tl(I) adsorption to ferrihydrite and heavier Tl isotope was slightly preferentially adsorbed on surface of ferrihydrite, which was attributed to the formation of inner-sphere complex between Tl and ≡Fe–OH. The findings offer a new understanding of the migration and fate of 205Tl/203Tl during Tl(I) adsorption to Fe (hydr)oxides.

Microbial diversity in paddy rhizospheric soils around a large industrial thallium-containing sulfide utilization zone

Thallium (Tl) is a rare and extremely toxic metal whose toxicity is significantly higher than cadmium (Cd), lead (Pb) and antimony (Sb). The extensive utilization of Tl-bearing minerals, such as mining activities, has led to severe Tl pollution in a variety of natural settings, while little is known to date about its effect on the microbial diversity in paddy soils. Also, the geochemical behavior of Tl in the periodical alterations between dry and wet conditions of paddy soils remains largely unknown. Herein, the sequential extraction method and 16S rRNA gene sequence analysis were adopted to analyze Tl's migration and transformation behavior and the microbial diversity in the paddy soils with different pollution levels. The results indicated that Tl was mainly concentrated in reducible fraction, which is different from other types of soils, and may be closely attributed to the abundance of Fe–Mn (hydr)oxides in the paddy rhizospheric soils. Further analysis revealed that pH, total S, Pb, Sb, Tl and Cd were the dominant environmental factors, and the enrichment level of these potentially toxic metal(loid)s (PTMs) exerted obvious impacts on the diversity and abundance of microorganism in the rhizospheric soils, and regulating microbial community. The geochemical fractionation of Tl was closely correlated to soil microorganisms such as Fe reducing bacteria (Geothrix) and sulfate reducing bacteria (Anaerolinea), playing a critical role in Tl geochemical cycle through redox reaction. Hence, further study on microorganisms of paddy rhizospheric soils is of great significance to the countermeasures for remediating Tl-polluted paddy fields and protect the health of residents.

Sorption behavior and mechanisms of thallium to microplastics

Thallium (Tl) is a metal of high toxicity, and the problem of Tl pollution is being faced globally. However, environmental data on Tl are still scarce and its biogeochemical behaviors remain mostly unclear. Studies have revealed the potential transport of other heavy metal by microplastics (MPs), but there is no report on the interactions between Tl and MPs yet. Therefore, we studied the adsorption of Tl by the three most commonly detected MPs, i.e., polyethylene (PE), polystyrene (PS), and polypropylene (PP) in fresh and seawater. We considered the effects of particle size, pH and competitive cations on adsorption capacity. The results showed PS has the highest adsorption capacity for Tl which was mainly through surface complexation. PS showed the lowest crystallinity and had the most oxygen-containing functional groups among the studied MPs. The adsorption of Tl on PE and PP was dominated by physical adsorption. The adsorptions exhibited significant salinity and pH dependence. Dominant cations in seawater competed with Tl ions for adsorption sites on MPs. With the increase in pH, the deprotonation of the carboxyl functional groups on MPs was enhanced, which increased the effective adsorption sites and promoted the adsorption of Tl. However, the adsorption capacity of the studied MPs for Tl was much lower than the corresponding capacity of natural minerals (clay, iron and manganese oxides) previously reported. Therefore, MPs may not be the main factors affecting the environmental behavior of Tl. This study provides valuable information for the study of thallium’s environmental behavior and ecological risk assessment.

Thallium distribution in an estuary affected by acid mine drainage (AMD): The Ría de Huelva estuary (SW Spain)

This study investigates the behavior of Tl in the Ría de Huelva (SW Spain), one of the most metal polluted estuaries in the world. Dissolved Tl concentration displayed a general decrease across the estuary during the dry season (DS); from 5.0 to 0.34 μg/L in the Tinto and Odiel estuaries, respectively, to 0.02 μg/L in the channel where the rivers join. A slighter decrease was observed during the wet season (WS) (from 0.72 to 0.14 μg/L to 0.02 μg/L) due to the dilution effect of rainfalls in the watersheds. These values are 3 orders of magnitude higher than those reported in other estuaries worldwide. Different increases in Tl concentrations with salinity were observed in the upper reaches of the Tinto and Odiel estuaries, attributed to desorption processes from particulate matter. Chemical and mineralogical evidences of particulate matter, point at Fe minerals (i.e., jarosite) as main drivers of Tl particulate transport in the estuary. Unlike other estuaries worldwide, where a fast sorption process onto particulate matter commonly takes place, Tl is mainly desorbed from particulate matter in the Tinto and Odiel estuaries. Thus, Tl may be released back from jarositic particulate matter across the salinity gradient due to the increasing proportion of unreactive TlCl0 and K+ ions, which compete for adsorption sites with Tl+ at increasing salinities. A mixing model based on conservative elements revealed a 6-fold increase in Tl concentrations related to desorption processes. However, mining spills like that occurred in May 2017 may contribute to enhance dissolved and particulate Tl concentrations in the estuary as well as to magnify these desorption processes (up to around 1100% of Tl release), highlighting the impact of the mine spill on the remobilization of Tl from the suspended matter to the water column.

Effect of peat organic matter on sulfide weathering and thallium reactivity: Implications for organic environments

Weathering of Tl-containing sulfides in a model (12-week) peat pot trial was studied to better understand their geochemical stability, dissolution kinetics, alteration products and the associated release and mobility of anthropogenic Tl in organic environments. We also present the effect of industrial acid rainwater on sulfide degradation and Tl migration in naturally acidic peat. Sphalerite (ZnS) was much less stable in peat than other Tl-containing sulfides (galena and pyrite), and thus acted as a major phase responsible for Tl mobilization. Furthermore, Tl incongruently leached out over Zn from ZnS, and accumulated considerably more in the peat solutions (≤5 μg Tl/L) and the peat samples (≤0.4 mg Tl/kg) that were subjected to acid rain watering compared to a deionized H2O regime. This finding was in good agreement with the absence of secondary Tl-containing phases, which could potentially control the Tl flux into the peat. The behavior of Tl was not as conservative as Pb throughout the trial, since a higher peat mobility and migration potential of Tl was observed compared to Pb. In conclusion, industrial acid precipitations can significantly affect the stability of ZnS even in acidic peat/organic environments, making it susceptible to enhanced weathering and Tl release in the long term.

Thermodynamic and kinetic coupling modeling for thallium(I) sorption at a heterogeneous titanium dioxide interface

The transformations of monovalent thallium (Tl) in an aqueous environment may be affected significantly by Tl(I) partitioning at the solid-water interface during sorption. Models used to quantify the kinetics of Tl(I) adsorption on heterogeneous adsorbents and formation of multiple complexes under a wide range of water chemistry conditions can accurately predict the environmental fate of thallium. In this study, Tl(I) sorption on representative titanium dioxide at different solution pH values and loading concentrations was investigated with two unified adsorption models, diffuse layer modeling and kinetics modeling. Three Tl(I) surface complexes, TiOTl, TiOHTl+, and TiOTlOH-, were used in the diffuse layer model and successfully described batch adsorption and the results of spectroscopic analyses. The contribution of TiOHTl+ to the adsorption capacity was much higher than those of TiOTl and TiOTlOH- under neutral and weakly alkaline conditions, while the species TiOTlOH- predominated among Tl(I) complexes in strongly alkaline environments. The adsorption and desorption rate coefficients derived from thermodynamics and kinetics coupling modeling suggested the influence of different complex characteristics on adsorption and desorption of Tl(I). Our results provide a comprehensive model for predicting the dynamic binding behavior of Tl at heterogeneous solid-water interfaces.

Kinetics of Thallium(I) Oxidation by Free Chlorine in Bromide-Containing Waters: Insights into the Reactivity with Bromine Species.

The oxidation of thallium [Tl(I)] to Tl(III) by chlorine (HOCl) is an important process changing its removal performance in water treatment. However, the role of bromide (Br-), a common constituent in natural water, in the oxidation behavior of Tl(I) during chlorination remains unknown. Our results demonstrated that Br- was cycled and acted as a catalyst to enhance the kinetics of Tl(I) oxidation by HOCl over the pH range of 5.0-9.5. Different Tl(I) species (i.e., Tl+ and TlOH(aq)) and reactive bromine species (i.e., HOBr/BrO-, BrCl, Br2O, and BrOCl) were kinetically relevant to the enhanced oxidation of Tl(I). The oxidation by free bromine species became the dominant pathway even at a low Br- level of 50 μg/L for a chlorine dose of 2 mg of Cl2/L. It was found that the reactions of Tl+/BrCl, Tl+/BrOCl, and TlOH(aq)/HOBr dominated the kinetics of Tl(I) oxidation at pH < 6.0, pH 6.0-8.0, and pH > 8.0, respectively. The species-specific rate constants for Tl+ reacting with individual bromine species were determined and decreased in the order: BrCl > Br2 > BrOCl > Br2O > HOBr. Overall, the presented results refine our knowledge regarding the species-specific reactivity of TI(I) with bromine species and will be useful for further prediction of thallium mobility in chlorinated waters containing bromide.

Thallium behavior during high-pressure metamorphism in the Western Alps, Europe

Thallium (Tl) is a highly incompatible element which can be redistributed during various igneous and hydrothermal events such as mineral dehydration and low-temperature hydrothermal alteration. Despite the strong influence fluid-rock interactions can have on Tl redistribution and the importance of fluids in subduction-zone volatiles cycling, the geochemical behavior of Tl during high-P/T metamorphism has not yet been quantified. Here we provide new Tl isotope composition (ε205Tl) and concentration ([Tl]) data for a suite of 18 metapelite and metacarbonate rocks from the Schistes Lustrés Complex and the nearby Lago di Cignana exposure in the western Alps. This suite represents metamorphism over a range of peak metamorphic P-T conditions of 300–550 °C and 1.5–3.0 GPa (similar to the range of P-T experienced in most modern subduction zones).With increasing metamorphic grade, [Tl] shows no statistical variation while ε205Tl initially remains fairly constant (in order of increasing grade, Fraiteve (unit A) ε205Tlavg = −2.1 (± 0.3); Assietta (unit B) ε205Tlavg = −1.6 (± 0.6); Albergian (unit C) ε205Tlavg = −1.9 (± 0.5)) before shifting to more negative values during higher grade metamorphism (Finestre (unit D) ε205Tlavg = −2.4 (± 0.3); Cignana (unit E) ε205Tlavg = −3.5 (± 0.3)). Although it appears likely that Tl is largely retained in such rocks to depths approaching those of arc magma generation, the mineralogical hosts for Tl change during prograde devolatilization. This may contribute to a significant shift in ε205Tl related to fractionation induced by only minor amounts of loss due to fluid-mineral partitioning. Prograde metamorphism results in the breakdown of chlorite and other minor mineralogical constituents, releasing chlorite-borne Tl that could be in part incorporated into phengite and in part lost to fluids. This study emphasizes the need for prograde mineral reaction history to be considered in studies of the retention or loss of trace elements such as Tl.

Thallium in aquatic environments and the factors controlling Tl behavior.

Although thallium (Tl) usually exists in a very low level in the natural environment, it is highly toxic. With the development of mining and metallurgical industry and the wide application of Tl in the field of high technologies, Tl poses an increasing threat to the ecological environment and human health. This paper summarizes the research results of the toxicity of Tl as well as the distribution, occurrence forms, migration, and transformation mechanism of Tl in rivers, lakes, mining areas, estuaries, coastal waters, and oceans. It also discusses the influence mechanisms of pH, redox potential, suspended particulate matters, photochemical reaction, natural minerals, cation/anion, organic matters, and microorganisms on the environmental behavior of Tl. This paper points out the shortcomings of Tl research methods in water environment, and looks forward to the future development directions: First, the technology for separating Tl(III) and Tl(I) is still immature, especially it is difficult to effectively separate Tl(III) and Tl(I) in seawater. Second, the development of many advanced in situ detection technologies will bring great convenience to the studies of the dynamic mechanisms of Tl migration and transformation in the environments. Third, adsorption is the most effective mechanism to remove Tl from water, in which modified metal oxides or macrocyclic organic compounds have high application potential.

Biogeochemical cycling of molybdenum and thallium during a phytoplankton summer bloom: A mesocosm study

Molybdenum (Mo) and thallium (Tl) are known as conservative-type elements in open ocean settings, despite their involvement in bio-cycling processes. In coastal oceans like the southern North Sea, however, positive and negative anomalies of dissolved Mo and Tl concentrations occur during certain time periods of the year, which are characterized by intensive organic matter cycling. The main motivation of the present study was to identify potential drivers for the non-conservative behavior of Mo and Tl. For this purpose, we conducted an indoor mesocosm experiment with natural seawater and sediment (including a natural microorganism community) and applied close to natural light and tidal (diurnal) conditions. After an incubation time of 35 days, we initialized a storm event to examine its influence on organic matter as well as nutrient and trace metal cycling. The temporal pattern of the inorganic macronutrients (N-species, dissolved phosphorous, dissolved silicate) as well as dissolved and particulate organic matter was highly dependent on the interplay of the phytoplankton and its associated bacteria bloom. Our results suggest that the redox-sensitive trace metals manganese (Mn), vanadium (V) and iron (Fe) were involved in bio-cycling processes. While temporal pattern of dissolved Mn and V were likely induced by active (macro-)nutrient assimilation rather than redox induced phase changes, dissolved Fe was present as organo-metallic complex and shielded from the flocculation as metal oxide. Our results further reveal positive Mo and negative Tl anomalies, especially during pre-storm conditions. The additional input of Mo was derived from the oxidation of reducing bottom sediments. Thereby, the degree as well as the rate of Mo-input was dependent on the composition of the background sediment. In the water column Mo was not only present in its dissolved oxidized form but was also stabilized by organic (algae-detritus, ligands) and inorganic (aluminosilicates) binding partners, preventing its (re-)deposition. Negative Tl anomalies were found to be induced by its immobilization by organic (algae-detritus, ligands) and inorganic (aluminosilicates) carrier phases in the water column prior to its deposition and potential fixation in the sulfidic bottom sediments. Particles derived from the storm event did not have any considerable effect on dissolved organic nor inorganic compounds, as they (re-)deposited before significant remineralization processes could take place.

Development of a Bi/Tl separation scheme for the proof of 209Bi \u03b1-decay in old mineral samples

The aim of this study is the development of a separation technique for geological samples, namely bismuthinites, with the goal to isolate Tl from excess amounts of Bi. This will enable an isotopic measurement of the Tl content on the ultra-trace level to identify a possible signature of Bi α-decay. The separation of Tl from other elements like e.g. Pb has been the subject of numerous studies. However, the separation of ultra-traces of Tl from bulk Bi had not yet been investigated sufficiently. This paper describes a separation technique for the system Bi/Tl for application to ultra-trace analysis. The separation technique uses a column chromatographic system, utilizing the specific redox behavior of Tl. The results show, that Tl can be successfully separated in appearance of vast excess amounts of Bi, showing recovery rates up to 96%. The developed procedure was successfully applied for the ultra-trace analysis on a number of bimuthinites using ICP-MS. On base of the results it is discussed, which prerequisites bimuthinite samples must fulfill to be suitable for the quantification of Bi alpha decay on base of the Tl isotopic ratio.

Thallium(I) sequestration by jarosite and birnessite: Structural incorporation vs surface adsorption

Jarosite and birnessite secondary minerals play a pivotal role in the mobility, transport and fate of trace elements in the environment, although geochemical interactions of these compounds with extremely toxic thallium (Tl) remain poorly known. In this study, we investigated the sorption behavior of Tl(I) onto synthetic jarosite and birnessite, two minerals commonly found in soils and sediments as well as in mining-impacted areas where harsh conditions are involved. To achieve this, sorption and desorption experiments were carried out under two different acidic conditions and various Tl(I) concentrations to mimic natural scenarios. In addition, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) analyses were conducted to determine the performance of both minerals for Tl(I) sequestration. Our results indicate that both phases can effectively remove aqueous Tl by different sorption mechanisms. Jarosite preferentially incorporates Tl(I) into the structure to form Tl(I)-jarosite and eventually the mineral dorallcharite (TlFe3(SO4)2(OH)6) as increasing amounts of Tl are employed. Birnessite, however, favorably uptakes Tl(I) through an irreversible surface adsorption mechanism, underlining the affinity of Tl for this mineral in the entire concentration range studied (0.5–5 mmol L−1). Lastly, the presence of Tl(I) in conditions where aqueous molar ratio Tl/Mn is ∼0.25 inhibits the formation of birnessite since oxidation of Tl(I) to Tl(III) followed by precipitation of avicennite (Tl2O3) take place. Thus, the present research may provide useful insights on the role of both jarosite and birnessite minerals in Tl environmental cycles.

Adsorption of thallium(I) on rutile nano-titanium dioxide and environmental implications.

Rutile nano-titanium dioxide (RNTD) characterized by loose particles with diameter in 20–50 nm has a very large surface area for adsorption of Tl, a typical trace metal that has severe toxicity. The increasing application of RNTD and widespread discharge of Tl-bearing effluents from various industrial activities would increase the risk of their co-exposure in aquatic environments. The adsorption behavior of Tl(I) (a prevalent form of Tl in nature) on RNTD was studied as a function of solution pH, temperature, and ion strength. Adsorption isotherms, kinetics, and thermodynamics for Tl(I) were also investigated. The adsorption of Tl(I) on RNTD started at very low pH values and increased abruptly, then maintained at high level with increasing pH >9. Uptake of Tl(I) was very fast on RNTD in the first 15 min then slowed down. The adsorption of Tl(I) on RNTD was an exothermic process; and the adsorption isotherm of Tl(I) followed the Langmuir model, with the maximum adsorption amount of 51.2 mg/g at room temperature. The kinetics of Tl adsorption can be described by a pseudo-second-order equation. FT-IR spectroscopy revealed that -OH and -TiOO-H play an important role in the adsorption. All these results indicate that RNTD has a fast adsorption rate and excellent adsorption amount for Tl(I), which can thus alter the transport, bioavailability and fate of Tl(I) in aqueous environment.

Solid-phase distribution and mobility of thallium in mining-metallurgical residues: Environmental hazard implications

Thallium (Tl) and its compounds are non-essential and highly toxic for living organisms, even at low concentrations. In this paper, we analyzed the presence and geochemical distribution of Tl in different mining-metallurgical and sediment samples collected from several mining zones of Mexico. A modified BCR sequential extraction procedure was also applied to the samples to investigate the geochemical behavior and potential environmental risk of Tl according to types of ore deposit and mineral processing method applied. Results revealed the presence of Tl in the majority of the mining-metallurgical samples, with labile concentrations reaching up to values of 184.4 mg kg−1, well above the environmental standards. A comparison of Tl partitioning in different samples showed that Tl was usually found associated with labile fractions instead of entrapped in the environmentally-passive residual fraction. Specifically, high levels of Tl were extracted from the exchangeable/acid-extractable and poorly-crystalline reducible fractions, suggesting its association with both soluble and amorphous Fe-Mn oxyhydroxides, respectively. Besides, Tl was also frequently found associated with the crystalline reducible fraction, presumably bonded to manganese oxides and jarosite-like minerals. Lastly, little amounts of Tl were extracted from the oxidizable fraction. Considering the fractionation of Tl in these mining-metallurgical samples, they may pose a significant environmental hazard. This study provides useful insights into the potential sources of Tl pollution in Mexico and emphasizes the need for further research to determine the extent of its impact and to develop effective remediation protocols to protect the environment from Tl toxicity.

The behavior of chalcophile elements during magmatic differentiation as observed in Kilauea Iki lava lake, Hawaii

We quantify the behavior of Cu, Ga, Ge, As, Mo, Ag, Cd, In, Sn, Sb, W, Tl, Pb, and Bi during the differentiation of a picritic magma in the Kilauea Iki lava lake, Hawaii, using whole rock and glass differentiation trends, as well as partition coefficients in Cu-rich sulfide blebs and minerals. Such data allow us to constrain the partitioning behavior of these elements between sulfide and silicate melts, as well as the chalcophile element characteristics of the mantle source of the Kilauea lavas. Nearly all of the elements are generally incompatible on a whole-rock scale, with concentrations increasing exponentially below ∼6wt% MgO. However, in-situ laser ablation data reveal that Cu, Ag, Bi, Cd, In, Pb, and Sn are chalcophile; As, Ge, Sb, and Tl are weakly chalcophile to lithophile; and Mo, Ga, and W are lithophile. The average Dsulfide/silicate melt values are: DAg=1252±1201 (2SD), DBi=663±576, DCd=380±566, DIn=40±34, DPb=34±18, DSn=5.3±3.6, DAs=2.4±7.6, DGe=1.6±1.4, DSb=1.3±1.5, DTl=1.1±1.7, DMo=0.56±0.6, DGa=0.10±0.3, and DW=0.11±0.1. These findings are consistent with experimental partitioning studies and observations of Ni-rich sulfide liquid in mid-ocean ridge basalts (MORB), despite the different compositions of the KI sulfides. The KI glasses and whole rocks are enriched in As, Ag, Sb, W, and Bi, relative to elements of similar compatibility (as established by abundances in MORB), mimicking enrichments found in basalts from the Manus back arc basin (Jenner et al., 2012) and the upper continental crust (UCC). These enrichments suggest the presence of terrigenous sediments in the Kilauea mantle source. The KI source is calculated to be a mixture of depleted MORB mantle (DMM) and 10–20% recycled crust composed of MORB and minor terrigenous sediments.

Chemistry and phase evolution during roasting of toxic thallium-bearing pyrite

In the frame of a research project on microscopic distribution and speciation of geogenic thallium (Tl) from contaminated mine soils, Tl-bearing pyrite ore samples from Riotinto mining district (Huelva, SW Spain) were experimentally fired to simulate a roasting process. Concentration and volatility behavior of Tl and other toxic heavy metals was determined by quantitative ICP-MS, whereas semi-quantitative mineral phase transitions were identified by in situ thermo X-Ray Diffraction (HT-XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) analyses after each firing temperature.Sample with initial highest amount of quartz (higher Si content), lowest quantity of pyrite and traces of jarosite (lower S content) developed hematite and concentrated Tl (from 10 up to 72 mg kg−1) after roasting at 900 °C in an oxidizing atmosphere. However, samples with lower or absent quartz content and higher pyrite amount mainly developed magnetite, accumulating Tl between 400 and 500 °C and releasing Tl from 700 up to 900 °C (from 10–29 mg kg−1 down to 4–1 mg kg−1). These results show the varied accumulative, or volatile, behaviors of one of the most toxic elements for life and environment, in which oxidation of Tl-bearing Fe sulfides produce Fe oxides wastes with or without Tl. The initial chemistry and mineralogy of pyrite ores should be taken into account in coal-fired power stations, cement or sulfuric acid production industry involving pyrite roasting processes, and steel, brick or paint industries, which use iron ore from roasted pyrite ash, where large amounts of Tl entail significant environmental pollution.