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The prevalence of toxic element thallium (Tl) in soils is of increasing concern as a hidden hazard in agricultural systems and food chains. In the present work, pure biochar (as a comparison) and jacobsite (MnFe 2 O 4)-biochar composite (MFBC) were evaluated for their immobilization effects in Tl-polluted agricultural soils (Tl: ∼10 mg/kg). Overall, MFBC exhibited an efficient effect on Tl immobilization, and the effect was strengthened with the increase of amendment ratio. After being amended by MFBC for 15 and 30 days, the labile fraction of Tl in soil decreased from 1.55 to 0.97 mg/kg, and from 1.51 to 0.88 mg/kg, respectively. In addition, pH (3.05) of the highly acidic soil increased to a maximum of 3.97 after the immobilization process. Since the weak acid extractable and oxidizable Tl were the preponderantly mitigated fractions and displayed a negative correlation with pH, it can be inferred that pH may serve as one of the most critical factors in regulating the Tl immobilization process in MFBC-amended acidic soils. This study indicated a great potential of jacobsite-biochar amendment in stabilization and immobilization of Tl in highly acidic and Tl-polluted agricultural soils; and it would bring considerable environmental benefit to these Tl-contaminated sites whose occurrence has significantly increased in recent decades near the pyrite or other sulfide ore mining and smelting area elsewhere. [Display omitted] • Jacobsite-biochar composite (MFBC) was applied to amend Tl-contaminated soils for the first time. • MFBC showed an efficient Tl immobilization effect especially with a 30-day amendment. • After amendment, the highly acidic soils' pH increased up to 30%. • The weak acid extractable and oxidizable Tl were the most mitigated fractions. [ABSTRACT FROM AUTHOR]

Abstract Thallium (Tl) is a typical toxic metal, which poses a great threat to human health through drinking water and the food chain (biomagnification). China has rich Tl-bearing mineral resources, which have been extensively explored and utilized, leading to release of large amounts of Tl into the environment. However, research on Tl pollution and removal techniques is relatively limited, because Tl has not been listed within the scope of environmental monitoring in China for several decades. This paper reviewed Tl pollution in wastewater arising from various industries in China, as well as the latest available methods for treating Tl-containing industrial wastewater, in order to give an outlook on effective technologies for controlling Tl pollution. Conventional physical and chemical treatment technologies are efficient at removing trace amounts of Tl, but it proved to be difficult to achieve the stringent environmental standard (≤0.1–5 μg/L) cost-effectively. Adsorption by using newly developed nanomaterials, and metal oxide modified polymer materials and microbial fuel cells are highly promising and expected to become next-generation technologies for remediation of Tl pollution. With the potential for greater Tl contamination in the environment under accelerated growth of industrialization, researches based on lab-scale implementation of such promising treatment technologies should be further expanded to pilot and industrial scale, ensuring environmental protection and the safety of drinking water for sustainable development. Comprehensive insights into experiences of Tl pollution in China and in-depth perspectives on new frontier technologies of Tl removal from wastewaters will also benefit other nations/regions worldwide, which are susceptible to high exposure to Tl likewise. Highlights • Thallium (Tl) is highly toxic whereas understudied as compared to other metals. • Booming Tl pollution is occurring in China very recently. • Various sources were reviewed for soaring Tl pollution in wastewater in China. • Traditional methods are hard to meet environmental standards cost-effectively. • New frontier technologies of Tl removal benefit all nations faced high Tl exposure. [ABSTRACT FROM AUTHOR]

Abstract Thallium (Tl) is a very toxic heavy metal. As a part of ongoing investigations, the mobility, sources and fate of Tl were investigated for sediments from a watershed in the northern part of the Pearl River, South China, whose catchment has been seriously impacted by large-scale Pb Zn smelting activities onshore. A wide dispersion of severe Tl contamination was observed throughout the depth profiles. A modified IRMM (Institute for Reference Materials and Measurements, Europe) sequential extraction procedure of a selected depth profile uncovered an exceptionally high enrichment of Tl in geochemically-mobile fractions (i.e., weak-acid-exchangeable, reducible and oxidizable fractions), on average 5.94 ± 2.19 mg/kg (74.6% ± 5.1% of the total Tl content) not only in the surface sediments but also in deep sediments. The proximal quantitative source apportionment using Pb isotopic fingerprinting technique indicated that a majority (80%–90%) of Tl contamination along the depth profiles is anthropogenically derived from the Pb Zn smelting wastes. The results highlight the pivotal role of smelting activities in discharging huge amounts of geochemically-mobile Tl to the sediments down to approximately 1 m in length, which is quantitatively evidenced by Pb isotopic tracing technique. Lead isotopes combined with distribution of Tl and Pb contents identified a potential marker for a point source from the Pb Zn smelter in the river catchment, which also provides a theoretical framework for source apportionment of metal contamination in a larger river/marine system and in other sulfide mining/smelting areas likewise. Highlights • Co-existent high contamination of Tl and Pb was observed across the sediment profiles. • Overall high proportion (∼75% on average) of Tl was found in the geochemically mobile fractions of all sediments. • Pb isotopic tracer technique suggests 80%–90% of Tl contamination in the sediments arising from Pb-Zn smelting activities. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is an extremely toxic metal, whose geochemical behavior remains poorly understood. This study aims to clarify the migration pathway and source apportionment of Tl in sediments from a watershed downstream of an open and large-scale pyrite mine area in south China, using high-precised Tl isotopic compositions. Results showed that Tl isotopic fractionations were mainly influenced by the anthropogenic Tl sources in all the sediments as a whole from the studied watershed, while in situ mineral adsorption and biological activity were limited. Moreover, plot of ε 205Tl vs. 1/Tl further illustrated that three possible end-members, viz. background sediments, pyrite tailings, and sewage treatment wastes were ascribed to predominant sources of Tl enrichment in the sediments. A ternary mixing model unveiled that waste from pyrite mining activities (i.e. , both pyrite tailings and sewage treatment wastes) affected the downstream sediments up to 10 km. All these findings suggest that Tl isotopic signature is a reliable tool to trace Tl sources in the sediments impacted by mining activities. It is highly critical for further target-oriented and precise remediation of Tl contamination. [Display omitted] • Thallium isotopes provide a precise estimation of Tl source and migration pattern. • Pyrite tailings and sewage wastes act as vital sources of Tl contamination. • Thallium isotopic signatures of sources were well preserved in the sediments. • Different waste from pyrite mining affected sediments downstream up to 10 km. [ABSTRACT FROM AUTHOR]

• A novel α-FeOOH@BC composite was designed to efficiently separate Tl from synthetic industrial wastewater. • Distribution coefficients higher than 5000 mL/g were achieved for wide pH range (5.0–11.0). • Tl separation mechanism consists of electrostatic attraction, ion exchange and complexation. • α-FeOOH@BC may serve as a prospective separation material for Tl(I) containing wastewater. Thallium (Tl) is an untraditional toxic metal. Emerging Tl pollution has received increasing concerns. Despite its extreme biotoxicity, Tl is an irreplaceable element for specific high-tech fields (e.g., superconductors, semiconductors, and optical fibers) due to its peculiar physio-chemical properties. Besides, Tl has been also regarded as critical strategic metal owing to its low abundance and scarcity in the earth's crust. Herein, a novel composite of α-FeOOH@BC was facilely synthesized via biochar modification with environmentally abundant iron oxides (α-FeOOH) to separate Tl(I) from wastewater. The results showed that overall large distribution coefficient values (K d > 5000 mL/g) of Tl separation by α-FeOOH@BC in a wide pH range (5.0–11.0) were achieved, suggesting a generally promising Tl separation capacity. Multiple characterizations with Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) indicate that the dominant Tl separation mechanisms included electrostatic attraction, ion exchange and complexation. These findings indicate that the α-FeOOH@BC material may have important application in Tl separation from industrial wastewaters, which are usually moderately acidic with pH values ranging from 5.0 to 7.0. This study offers novel perspectives on using environmental abundant iron oxides modified biochar for easy and fast separation of Tl from industrial wastewater. All these findings can facilitate to develop waste-to-resources strategy for recycling Tl in the loop of circular economy and industrial symbiosis. [ABSTRACT FROM AUTHOR]

Thallium is a highly toxic element, whose geochemical dispersion, transfer and potential health risks in aquatic systems are far from understood. This study aims to investigate the distribution of Tl in the surface water from an ultra-large Tl-bearing pyrite open-mining site and its associated riverine system of Yunfu city, western of the Pearl River Basin (PRB). Concentrations of 2.75–194.4 μg/L of Tl were found in the surface water from the mining site. Compared with other trace metals measured (Al, As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn), Tl experienced little precipitation by conventional lime-dosing treatment of mine water and readily moved through the river trace. The distribution of Tl in the river watershed during both the dry season (Tl: 0.01–9.15 μg/L) and wet season (Tl: 0.03–1.92 μg/L) generally followed a decreasing concentration pattern downstream of the pyrite mining site for the upper and middle reaches. However, some unexpected Tl elevations were observed in the lower reaches. Concentrations of Tl correlated well with concentrations of Ca, Mn, Sr, sulfate, total dissolved solids and water conductivity values for both the dry season and the wet season. Finally, health risk assessment suggests that Tl may pose non-carcinogenic health risks to local residents over a long time. This study highlights not only anthropogenically-induced but also hidden naturally-occurring Tl enrichment in the hydrosphere of the PRB, and enhances the understanding of aqueous geochemistry of Tl. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Thallium(Tl), an extremely toxic metal, is posing great hazards to water safety through anthropogenic activities (e.g., Pb-Zn smelter) and natural weathering in riverine systems. However, the relative contribution from each source remains obscure. This study investigated enrichment pattern of Tl and its isotopic compositions in sediment profiles from a recipient river, which was continuously collecting various Tl-bearing wastes discharged from a large Pb-Zn smelter in South China. Results show that high Tl content and ultra-fine particles (~ μm) of Tl-bearing mineral assemblages, probably derived from Pb-Zn smelting wastes, were ubiquitously observed in both of the depth profiles. In addition, the sediments generally yielded intermediate ε 205Tl values of –3.76 to 1.01, which resembled those found in smelting wastes. A ternary mixing model was for the first time proposed for quantifying relative Tl contributions from each possible source. The calculation suggests that the smelter wastes are the major contributors, contributing approximately 80% of Tl contamination. All these results indicate that Tl isotope can be used as powerful proxies for quantitatively identifying potential different contributors in the environment. This is of critical importance to further implementation of pollution control and remediation strategy for the riverine systems in the near future. [Display omitted] • Assemblages of Tl-bearing fine particle minerals (e.g. lorandite) were observed in the sediments. • The acidic waste and smelter clinker mainly contributed Tl contamination to the sediments. • The ternary mixing model of Tl isotope can quantitatively trace Tl contamination. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is a trace metal with high toxicity. Comprehensive investigation of spatial distribution of Tl and microorganism is still limited in soils from mining area. In this study, 16S rRNA sequencing and network analysis were used for deciphering the co-occurrence patterns of bacterial communities in two different types of soil profiles around a typical Tl-bearing pyrite mine. The results showed that geochemical parameters (such as pH, S, Tl, Fe and TOM) were the driving forces for shaping the vertical distribution of microbial community. According to network analysis, a wide diversity of microbial modules were present in both soil profiles and affected by depth, significantly associated with variations in Tl geochemical fractionation. Phylogenetic information further unveiled that the microbial modules were mainly dominated by Fe reducing bacteria (FeRB), Fe oxidizing bacteria (FeOB), S oxidizing bacteria and Mn reducing bacteria. The results of metagenome indicated that Fe, Mn and S cycle in soil are closely involved in the biogeochemical cycle of Tl. The findings of co-occurrence patterns in the bacterial network and correlation between microorganisms and different geochemical fractions of Tl may benefit the strategy of bioremediation of Tl-contaminated soils with indigenous microbes. [Display omitted] • Extremely toxic thallium(Tl) can influence the composition of soil microbial community. • Geochemical factors reshape microbial distribution under the stress of Tl contamination. • Microbial cycling of Fe, Mn and S may benefit the adaption to Tl pollution in soils. [ABSTRACT FROM AUTHOR]

Thallium (Tl), vanadium (V) and arsenic (As) are considered as typical toxic elements of increased interest. Their accumulation in soils can pose a substantial health threat to human beings. In this study, Fe–Mn modified biochar (FMBC) was chemically constructed to immobilize Tl, V and As in contaminated soils. The results showed that compared with pristine biochar (BC), FMBC can achieve significantly higher passivation effects for the studied contaminated soils, which reduced the bioavailable Tl, V and As contents by 83.9%, 71.09% and 71.92%, respectively. The passivation of Tl, As, and V via FMBC application was partially attributed to a notable increase in pH, which enhances the availability of adsorptive sites. Further, the newly formed minerals, including cancrinite, gibbsite and Fe–Mn (hydr)oxides, serve as additional adsorbents, substantially reducing the mobility of Tl, V and As. Additionally, the oxidation of Tl(I) to Tl(III) by the Fe–Mn (hydr)oxide of FMBC significantly enhanced Tl immobilization, consequently diminishing its bioavailability. The findings suggest that significant environmental threats could be alleviated through the potential application of FMBC in treating Tl-As-V dominated contamination in soils, providing a new perspective for the sustainable utilization of industrially polluted soils. Highlights: FMBC effectively reduced the bioavailability of Tl, As and V in contaminated soils. Formation of new minerals during passivation can enhance adsorption of the studied elements. Effective immobilization of Tl may be mainly ascribed to oxidation of Tl(I) to Tl(III) by FMBC. [ABSTRACT FROM AUTHOR]

Abstract: The sorption behaviour of the severely toxic heavy metal thallium (Tl) as a monovalent cation onto three representative materials (goethite, pyrolusite and a natural sediment sampled from a field site) was examined as a function of pH in the absence and presence of two natural humic acids (HAs), using 204Tl(I) as a radiotracer. In order to obtain a basic understanding of trends in the pH dependence of Tl(I) sorption with and without HA, sorption of HAs and humate complexation of Tl(I) as a function of pH were investigated as well. In spite of the low complexation between Tl(I) and HAs, the presence of HAs results in obvious alterations of Tl(I) sorption onto pyrolusite and sediment. An influence on Tl(I) sorption onto goethite was not observed. Predictions of K d (distribution coefficient) for Tl(I) on goethite in the presence of HAs, based on a linear additive model, agree well with the experimental data, while a notable disagreement occurs for the pyrolusite and sediment systems. Accordingly, it is suggested that HAs and goethite may act as a non-interacting sorbent mixture under the given conditions, but more complex interactions may take place between the HAs and the mineral phases of pyrolusite or sediment. [ABSTRACT FROM AUTHOR]

• MnFe 2 O 4 -biochar composite was facilely synthesized based on common biowastes. • The novel composite has large specific surface area and rich functional groups. • The composite shows efficient and high Tl(I) removal capacity. • Multi-mechanisms involved in the effective Tl(I) removal were examined and distinguished. Thallium (Tl), is a highly toxic trace metal in the natural environment. Emerging Tl pollution in waters has gradually become a global concern. However, limited removal technologies are available for Tl-containing wastewater. Herein, MnFe 2 O 4 -biochar composite (MFBC) was successfully fabricated via coprecipitation method as a novel and efficient adsorbent for treating Tl(I)-contaminated wastewater. It was found that the MFBC, with a specific surface area of 187.03 m2/g, exhibited high performance across a wide pH range of 4–11, with the superior Tl(I) removal capacity (170.55 mg/g) based on Langmuir model (pH 6.0, a dosage of 1 g/L). The removal mechanisms included physical and chemical adsorption, ion exchange, surface complexation, and oxidation. This investigation revealed that MFBC is a promising and environmentally friendly adsorbent with a low cost, large specific surface area, magnetic properties, and high efficiency for the removal of Tl(I) from wastewater. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is an extremely toxic element, whose toxicity is even higher than mercury, arsenic, and cadmium. It is of great significance to hinder the migration and transfer of Tl from soils to the plants. A synthetic mineral amendment (SMA), mainly composed of different silicates, was evaluated for its effects on the transformation and retention of Tl in two typical highly Tl-contaminated soils from Southwest China. The results indicated that the addition of mineral amendment increased the soil of the pH by 0.46–2.13 units and distinctly reduced the content of active thallium in the soils. The extent of Tl reduction was related to the morphological characteristics of the original soil In particular, the application of the mineral amendment transformed 25.8–52.5% of the active Tl fractions in the soils to the residual fraction at 60 d. Adding mineral amendment to the soils can provide conditions to facilitate Tl to enter the silicate crystal lattice. The results of XPS evidenced that the proportion of Tl(I) in the soil was greatly reduced after adding the mineral amendment. • A synthetic mineral amendment (SMA) was applied to restore thallium (Tl) polluted soil. • SMA transformed 25.8–52.5% of the active Tl fractions to the residual fraction. • The proportion of Tl(I) in soil was greatly decreased after SMA was applied. • SMA immobilization method provides practical significance in Tl hazard mitigation. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is an uncommon toxic element, with an even greater toxicity than that of As, Hg and Cd. Steel-making industry has been identified as an emerging new significant source of Tl contamination in China. This paper presents a pilot investigation of the contamination and geochemical transfer of Tl and associated metal(loid)s in river sediments affected by long-term waste discharge from the steel-making industry. The results uncovered an overall Tl contamination (1.96 ± 0.42 mg/kg) across a sediment profile of approximately 1.5 m in length, even 10 km downstream the steel plant. Highly elevated contents of Pb, Cu, Cd, Zn and Sb were found in the fluvial sediments, displaying strong positive correlations with Tl contents. Elevated levels of geochemically mobile Tl as well as Cd, Zn, Cu and Pb occurred in the fluvial sediments, signifying anthropogenic imprints from steel production activities at high temperature. Levels of contamination and ecological risk were calculated to be moderate to considerable for Tl, Cu, Zn and high to very high for Cd, Pb, Sb. The results highlight that there is a great challenge in view of potentially considerable Tl pollution due to continuous massive steel production in many other parts of China. It is high time to initiate process-based management of Tl contamination control for the ambient aquifer system in the steel-making area. Image 1 • Steel industry is an emerging new significant source of Tl pollution in China. • Steel-making activities have generated Tl contamination imprints in river sediments. • High levels of Tl as well as Pb, Zn, Cd, and Sb were identified in the sediments. • Higher than 30% of Tl is geochemically mobile, bearing high ecological risks. • It indicates great challenge for Tl pollution in China due to massive steel industry. [ABSTRACT FROM AUTHOR]

Thallium is a highly poisonous heavy metal. Since Tl pollution control has been neglected worldwide until the present, countless Tl pollutants have been discharged into the environment, endangering the safety of drinking water, farmland soil, and food chain, and eventually posing a great threat to human health. However, the source, occurrence, pathway and fate of Tl in the environment remains understudied. As Tl in non-contaminated systems and from anthropogenic origin exhibits generally different isotopic signatures, which can provide fingerprint information and a novel way for tracing the anthropogenic Tl sources and understanding the environmental processes. This review summarizes: (i) the state-of-the-art development in highly-precise determination analytical method of Tl isotopic compositions, (ii) Tl isotopic fractionation induced by the low-temperature surface biogeochemical process, (iii) Tl isotopic signature of pollutants derived from anthropogenic activities and isotopic fractionation mechanism of Tl related to the high-temperature industrial activities, and (iv) application of Tl isotopic composition as a new tracer emerging tracer for source apportionment of Tl pollution. Finally, the limitations and possible future research about Tl isotopic application in environmental contamination is also proposed: (1) Tl fractionation mechanism in different environmental geochemistry processes and industrial activities should be further probed comprehensively; (2) Tl isotopes for source apportionment should be further applied in other different high Tl-contaminated scenarios (e.g., agricultural systems, water/sediment, and atmosphere). [ABSTRACT FROM AUTHOR]

Thallium (Tl) is a typical toxic heavy metal, with higher toxicity to mammals than Hg, Cd, and Pb. Accurate assessments of its environmental exposure and flux are central to effective management and control of Tl pollution. This paper first presents in detail the environmental exposure and flux of Tl by typical industrial activities utilizing Tl-bearing pyrite minerals to produce sulfuric acid. For this purpose, sequential extraction and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) were used to investigate total content and geo-chemical partitioning of Tl in raw pyrite ores and solid roasting wastes, thereby uncovering Tl distribution and transformation during the production process. Results showed that some portions of Tl bearing in the minerals went into vapor, which transferred Tl into different processes; and some portions of Tl went into water during the gas washing procedure, leaving some other portions remained in the solid slags. More importantly, detailed investigation revealed that 40% of Tl in the pyrite minerals was active, among which 25% of Tl originally in the pyrite minerals was washed into water during gas cleaning process and 15% of active Tl retained in the slags. The latter portion of active Tl could be possibly transferred to the soil or water with the slag deposal or being reused; and 60% of Tl remained relatively stable in the residual phase. [ABSTRACT FROM AUTHOR]

• Combination of iron salts@BC with PS can efficiently remove Tl from solution. • FeCl 3 @BC-PS shows a marginally higher removal efficacy (96.5%) than Fe(NO 3) 3 -PS (94.1%). • Iron salts@BC-PS removes Tl mainly by chemical adsorption and oxidation process. • SO 4 − and OH are the vital radicals for transforming Tl(I) into Tl(III). Thallium is an emerging metallic pollutant with extremely high toxicity which resulted in worldwide water pollution in the past decades. It is critical to develop multiple alternative methods for Tl removal to enrich control strategy towards Tl pollution in aquatic environment. It is proposed herein a highly effective and environmental-friendly Tl removal method by applying iron salt-impregnated biochar (BC) combined with persulfate (PS), using two most common iron salts (FeCl 3 and Fe(NO 3) 3). It was found that FeCl 3 @BC-PS system achieved higher Tl removal capacity (164.42 mg/g), which exhibited a comparative preponderance relative to the reported iron based adsorbent composites, partially owing to significantly enhanced specific surface area (854.48 m2/g). The dominant Tl removal mechanisms include free radical based oxidation and chemical adsorption. Radical quenching experiments confirmed that SO 4 − and OH served as vital radicals for FeCl 3 @BC-PS and Fe(NO 3) 3 @BC-PS, respectively. The study provides a reliable alternative for Tl-wastewater treatment with PS activation by catalyst based on the synergistic effect of biochar and iron salts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two manganese oxide@potassium-rich biochars were constructed using banana peel wastes. • They exhibit higher Tl(I) removal efficiency while less dosage compared to most adsorbents reported. • Tl(I) removal was even promoted by S−MnxOy@BC in presence of DTPA or EDTA. • Cation exchange and oxide-coprecipitation are the prime mechanisms for Tl(I) removal. • S−Mn x O y @BC deserves promising application prospects in Tl(I)-associated wastewater treatment. Potassium(K)-rich biochar (BC) synthesized from waste banana peels were designed as green adsorbents for removal of TI(I) from aqueous solution. Co-precipitation and solid surface deposition method were adopted to fabricate two distinct manganese oxide biochars, i.e., H−Mn 3 O 4 @BC and S−Mn x O y @BC, respectively, which showed remarkably higher efficiency but with less dosage in treating Tl(I)-containing aqueous solution with the maximum adsorption capacities at 122.91 mg/g and 136.94 mg/g, respectively, than most adsorbents reported. Besides, H−Mn 3 O 4 @BC and S−Mn x O y @BC exhibited strong resistance to co-existing cations and organics interference on Tl(I) removal. Specially, DTPA and EDTA could coordinate with Mn(III) to promote the oxidation and removal of Tl(I). According to FTIR, H−Mn 3 O 4 @BC and S−Mn x O y @BC were enriched with abundant functional groups such as O H and Mn O, while the original C O on BC surface was oxidized by MnO 4 −. The results of SEM-EDS and XPS revealed that cation exchange and oxide-coprecipitation were the main mechanisms of Tl(I) removal by H−Mn 3 O 4 @BC and S−Mn x O y @BC. This study proposes a novel approach on facile design of potassium-rich biochars, which exhibited highly effective performance on Tl(I) removal from aqueous solution. The findings provide favorable alternative for synthesis of specially designed functional materials from naturally K-rich biowastes and show promising potential in efficient treatment with increasing occurrence of Tl(I)-containing wastewater. [ABSTRACT FROM AUTHOR]

In this study, Fe-Mn binary oxides, which harbor the strong oxidative power of manganese dioxide and the high adsorption capacity of iron oxides, were synthesized for Tl(I) removal using a concurrent chemical oxidation and precipitation method. The adsorption of Tl onto the Fe-Mn adsorbent was fast, effective, and selective, with equilibrium sorption reaching over 95% under a broad operating pH (3–12), and high ionic strength (0.1–0.5 mol/L). The adsorption can be well fitted with both Langmuir and Freundlich isotherms, and the kinetics can be well described by the pseudo-second-order model. Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) spectra suggest that surface complexation, oxidation and precipitation were the main mechanisms for the removal of Tl. This study shows that the Fe–Mn binary oxides could be a promising adsorbent for Tl removal. [ABSTRACT FROM AUTHOR]

Simultaneous removal of thallium (Tl) and chloride from a highly saline industrial wastewater was investigated using modified anion ion exchange resins. The removal of thallium was mainly driven by the exchange of Tl-chlorocomplex (TlCl 4 − ) formed in the oxidation of thallous (Tl (I)) to thallic ion (Tl (III)) by hydrogen peroxide (H 2 O 2 ) under saline conditions. Over 97% of thallium and chloride removal was achieved using the modified resins, with a wide optimal conditions found to be H 2 O 2 dosage 1.0–25.0 mL/L, pH 1.6–4.3, and flow rate 0.5–4.7 mL/L. The modified resins had an exchange capacity of 4.771 mg Tl/g dry resins for thallium and 1800 mg Cl/g dry resins for chloride. Stable regeneration could be achieved with the modified resins: over 97% of thallium and 90% of chloride can be eluted using Na 2 SO 3 solution and alternating hot (60 °C) H 2 SO 4 and cold (25 °C) water, and over 98% removal of thallium and chloride was achieved after five consecutive regeneration cycles. [ABSTRACT FROM AUTHOR]

Due to extreme toxicity of the element of thallium (Tl), increasing aqueous Tl pollution incidents have aroused growing concerns. As the prevalent and stable form, i.e. , monovalent Tl, the highly efficient removal methodologies of Tl(I) from (waste)water remains limited and challenging. In this study, an advanced oxidation method, the feasibility of using zero valent iron (Fe0) coupled with persulfate (PS) to treat Tl(I)-containing synthetic wastewater was investigated. Its influence parameters, including reaction time, initial Tl concentration, dosages of PS and Fe0, initial and coagulation pH, temperature, coexisting ions and organic matter (NO 3 −, SO 4 2−, Cl− and HA) were examined. The results revealed that the system can be applied to a wide range of pH and temperature and the reaction equilibrium can be reached in about 30 min. Favorable Tl(I) removal rate (>98%) was observed in the synthetic wastewater with medium and relatively high Tl(I) concentration (≤0.250 mM). The analyses of characterization results including electron spin resonance spectrometer and X-ray photoelectron spectroscopy indicated that ·OH played a vital role in the removal of Tl(I), which was oxidized and removed by co-precipitation. Fe0 can be served as a stable source of Fe2+ to efficiently catalyze PS. The remaining Fe0 can be easily separated because of its magnetism, assuring the promising reusability of the reactant. The study aims to provide references for treatment of real Tl polluted wastewater. [Display omitted] • Zero valent iron (Fe0)-persulfate (PS) was first used to treat Tl(I) in wastewater. • Fe0-PS system can efficiently treat Tl(I) in wastewater. • Initial pH and temperature have little effect on Tl(I) removal. • Hydroxyl radical played a vital role in the removal of Tl(I) via oxidation. • Fe-containing hydroxide played a vital role in the removal of Tl(I) via co-precipitation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Thallium (Tl) is a highly toxic heavy metal widely present in the environment. Case reports have suggested that maternal exposure to high levels of Tl during pregnancy is associated with low birth weight (LBW), but epidemiological data are limited. OBJECTIVES: This study was designed to evaluate whether prenatal Tl exposure is associated with an increased risk of LBW. METHODS: This case--control study involving 816 study participants (204 LBW cases and 612 matched controls) was conducted in Hubei Province, China, in 2012--2014. Tl concentrations were measured in maternal urine collected at delivery, and associations with LBW were evaluated using conditional logistic regression. RESULTS: Higher maternal urinary Tl levels were significantly associated with increased risk of LBW [crude odds ratio (OR) = 1.52; 95% CI: 1.00, 2.30 for the highest vs. lowest tertile], and the association was similarly elevated after adjustment for potential confounders (adjusted OR = 1.90; 95% CI: 1.01, 3.58 for the highest vs. lowest tertile). Stratified analyses showed slightly higher risk estimates for LBW associated with higher Tl levels for mothers < 28 years old and for mothers with lower household income; however, there was no statistical evidence of heterogeneity in risk according to maternal age (p for heterogeneity = 0.18) or household income (p for heterogeneity = 0.28). CONCLUSION: TO our knowledge, ours is the first case--control study to investigate the association between prenatal Tl exposure and LBW. The results suggest that prenatal exposure to high levels of Tl may be associated with an increased risk of LBW. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is an extremely toxic metal, while its occurrence and fate in paddy soil environment remain understudied. Herein, the enrichment and migration mechanisms and potential health risks of Tl and metal(loid)s were evaluated in paddy soils surrounding an industrial park utilizing Tl-bearing minerals. The results showed that Tl contamination was evident (0.63–3.16 mg/kg) in the paddy soils and Tl was generally enriched in root of rice (Oryza sativa L.) with a mean content of 1.27 mg/kg. A remarkably high level of Tl(III) (30–50%) was observed in the paddy soils. Further analyses by STEM-EDS and XPS indicated that Tl(I) in the paddy soils was jointly controlled by adsorption, oxidation, and precipitation of Fe/Mn(hydr)oxide (e.g. hematite and birnessite), which might act as important stabilization mechanisms for inhibiting potential Tl uptake by rice grains. The health quotient (HQ) values indicated a potentially high Tl risk for inhabitants via consumption of the rice grains. Therefore, it is critical to establish effective measures for controlling the discharge of Tl-containing waste and wastewater from different industrial activities to ensure food safety in the rice paddy soils. [Display omitted] • High content of Tl(III) existed in paddy soil during drainage stage. • Thallium(I) was oxidized to Tl(III) and adsorbed by Fe/Mn(hydr)oxides. • The adsorption and immobilization of Tl(III) decreased its bioaccumulation for rice. [ABSTRACT FROM AUTHOR]

Thallium (Tl) pollution caused by the exploitation of uranium (U) mines has long been neglected due to its low crustal abundance. However, Tl may be enriched in minerals of U ore because Tl has both sulfurophile and lithophile properties. Herein, a semi-dynamic leaching experiment combined with statistical analysis, geochemical speciation and multi-characterization provided novel insight into the distinct features and mechanisms of Tl release from uranium mill tailings (UMT). The results showed that particle size effects prevail over the pH on Tl release, and surface dissolution is the pivotal mechanism controlling Tl release based on Fick's diffusion model. The study revealed that long-term leaching and weathering can lead to the increased acid-extractable and oxidizable fractions of Tl in UMT, and that the exposure and dissolution of Tl-containing sulfides would largely enhance the flux of Tl release. The findings indicate that UMT containing (abundant) pyrite should be paid particular attention due to Tl exposure. Besides, critical concern over the potential Tl pollution in universal U mining and hydrometallurgical areas likewise may need to be seriously reconsidered. ga1 • Thallium (Tl) in uranium mill tailings (UMT) was mainly released by surface dissolution. • Particle size effect instead of leachant pH critically influenced Tl release. • Significantly increased labile Tl fraction was observed after 20 weeks' leaching. • Weathering based sulfide exposure largely facilitated Tl mobilization. • UMT containing pyrite should receive particular attention due to highly toxic Tl release. [ABSTRACT FROM AUTHOR]

• Vegetable grown soils were highly enriched with Tl, As, Pb, Cd, Cr, Cu and Mn. • Non-negligible potential health risk of toxic Tl, As, etc. in vegetables was found. • Carcinogenic risk is higher than the threshold for As, Cd and Cr. • Steel-making activities contribute 35–80% of Pb-As in vegetables via binary mixing model. Industrial activities tend to deteriorate adjacent agricultural lands due to accumulation of potentially toxic elements in soils and crops. However, better understanding of their distinctive source partitions and transfer process remains insufficient in steel-making area. The paper focuses on the pollution levels, health risks, and provenance identification of Tl, As, Pb, Cu, Ni, Co, Sb, Cd, Zn, Be, Cr, Fe, Mn, Mo, Sn, and V in common vegetables from different farmlands near a steel-making plant. The results showed that the Tl, As, Pb, Cd, Cr, Cu and Mn were of high-level contamination in soils and generally above the maximum permissible level (MPL). Calculation using hazard quotients (HQ) exhibited that consumption of the studied vegetables may entail significant health risks to residents, especially for children, resulting from the elevated contents of Tl, As and associated toxic elements. Calculation by binary mixing model using Pb isotopic compositions suggested that steel-making activities contributed to 35–80% of the contamination of Pb and As in vegetables. It is necessary to adopt appropriate remediation measures to mitigate the farmland contamination and ensure the food safety of the agricultural products. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is a trace element with extreme toxicity. Widespread Tl pollution in riverine systems, mainly due to escalating mining and smelting activities of Tl-bearing sulfide minerals, has attracted increasing attention. Insights into the function of the microbial communities with advanced characterization tools are critical for understanding the biogeochemical cycle of Tl. Herein, microbial communities and their adaptive evolution strategies in river sediments from a representative Tl-bearing pyrite mine area in southern China were profiled via 16S rRNA gene sequence analysis and shotgun metagenomic analysis. In total, 64 phyla and 778 genera of microorganisms were observed in the studied sediments. The results showed that pH, Tl, Pb, Zn and total organic carbon (TOC) had a significant influence on microbial community structure. Some important reductive microorganisms (such as Erysipelothrix , Geobacter , desulfatiferula , desulfatihabadium and fusibacter) were involved in the biogeochemical cycle of Tl. The ruv , rec , ars and other resistance genes enhanced the tolerance of microorganisms to Tl. The study suggested that relevant C, N and S cycle genes were the main metabolic paths of microorganisms surviving in the high Tl-polluted environment. The findings were critical for establishment, operation and regulation in the microbial treatment of Tl containing or related wastewater. Unlabelled Image • The metabolism of microbes in high thallium (Tl) polluted sediments was insighted. • Metabolite of iron/sulfate-reducing microbes might change Tl geochemical fractions. • Resistance genes such as ruv , rec and ars may enhance the microbes' tolerance to Tl. [ABSTRACT FROM AUTHOR]

• Co-hyperaccumulation of thallium(Tl) and arsenic(As) was found in brake ferns. • Remarkably high BCFs were observed for As (7.8) and even higher for Tl (28.4). • Preferential uptake of Tl(I) but of both As(III) and As(V) from soils was identified. • Brake ferns (Pteris vittata L.) may serve as promising As-Tl phytoremediation plant. Both thallium (Tl) and arsenic (As) bear severe toxicity. Brake fern (Pteris vittata L.) is well-known for its hyperaccumulation capacity of As, yet its role on Tl accumulation remains unknown. Herein, brake ferns growing near an As tailing site in Yunnan, Southwestern China are for the first time discovered as a co-hyperaccumulator of both Tl and As. The results showed that the brake ferns extracted both As and Tl efficiently from the soils into the fronds. The studied ferns growing on Tl and As co-polluted soils were found to accumulate extremely high levels of both As (7215–11110 mg/kg) and Tl (6.47–111 mg/kg). Conspicuously high bio-accumulation factor (BCF) was observed for As (7.8) and even higher for Tl (28.4) among these co-hyperaccumulators, wherein the contents of As and Tl in contaminated soils were 1240 ± 12 and 3.91 ± 0.01 mg/kg, respectively. The applied advanced characterization techniques (e.g. transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS)) indicated a preferential uptake of Tl(I) while simultaneous accumulation of As (III) and As(V) from the Tl(I)/Tl(III)-As (III)/As(V) co-existent rhizospheric soils. The findings benefit the phytoremediation practice and pose implications for managing and restoring Tl-As co-contaminated soils in other countries. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is an extremely toxic metal with high risk. Sediment samples from a well dated sediment core retrieved from a heavily polluted urban lake were measured to assess the magnitude of Tl pollution and reveal its transfer mechanisms within the lake. The results show that the lake has experienced serious Tl pollution during the past 60 years, owing to a large influx of Tl-bearing wastes mostly from a neighboring copper (Cu) smelter. The Tl contents in the sediment core at different depths generally correlated positively with the production scale of Cu smelting activities in the past. Further mineralogical analysis on the electrostatic precipitator dust from the Cu smelter and highly-polluted samples from the sediment core by electronic microscopy and X-ray diffraction suggested that Tl was primarily bound to quartz and aluminosilicates. Large quantities of Tl were also observed in diatom frustules collected from the sediments, suggesting a potentially significant role of biogenic silicates in the uptake and transfer of Tl in the sediment-water system. The findings indicate a new and emerging pollution source of thallium arising from copper metallurgy activities. The results also highlight the necessity of strengthened monitoring and regulations towards Tl pollution in environmental systems impacted by Cu smelting activities in China and other nations. • The Sanqi Lake was discovered with Tl pollution lasting for 60 years. • Tl pollution was attributed to Tl-bearing wastes from a Cu smelter nearby. • Various Tl-bearing smelter-derived minerals were disseminated into the lake. • Presence of Tl in microscale particles also indicates the link to Cu smelter. [ABSTRACT FROM AUTHOR]