Arsenic（As） is a notoriously toxic pollutant of health concern worldwide with potential risk of cancer induction, but meanwhile it is used as medicines for the treatment of different conditions including hematologic...Arsenic（As） is a notoriously toxic pollutant of health concern worldwide with potential risk of cancer induction, but meanwhile it is used as medicines for the treatment of different conditions including hematological cancers. Arsenic can undergo extensive metabolism in biological systems, and both toxicological and therapeutic effects of arsenic compounds are closely related to their metabolism. Recent studies have identified methylated thioarsenicals as a new class of arsenic metabolites in biological systems after exposure of inorganic and organic arsenicals, including arsenite, dimethylarsinic acid（DMAV）, dimethylarsinous glutathione（DMAIIIGS）, and arsenosugars. The increasing detection of thiolated arsenicals,including monomethylmonothioarsonic acid（MMMTAV）, dimethylmonothioarsinic acid（DMMTAV） and its glutathione conjugate（DMMTAVGS）, and dimethyldithioarsinic acid（DMDTAV） suggests that thioarsenicals may be important metabolites and play important roles in arsenic toxicity and therapeutic effects. Here we summarized the reported occurrence of thioarsenicals in biological systems, the possible formation pathways of thioarsenicals, and their toxicity, and discussed the biological implications of thioarsenicals on arsenic metabolism, toxicity, and therapeutic effects.展开更多
The thiourea leaching of gold from the calcine of gold-bearing arsenical pyrite concentrate of Kangjiawan mine was studied.The effects of the leaching time,the concentrations of thiourea,hydrochloric acid and initial ...The thiourea leaching of gold from the calcine of gold-bearing arsenical pyrite concentrate of Kangjiawan mine was studied.The effects of the leaching time,the concentrations of thiourea,hydrochloric acid and initial ferric ion on the leaching recovery of gold were investigated,and a regressive model has been established,which showed that the concentrations of thiourea and hydrochloric acid were the most important factors,leaching time the second,and concentration of the initial ferric ion the least・Under the optimal conditions,that is,temperature 50℃,the ratio of liquid to solid 4:1,thiourea 12g/L,hydrochloric acid 1 mol/L,and initial ferric ion 1 g/L,the leaching recoveries of gold and silver were more than 81%and 73%,respectively.The increase of silver recovery and the reduction of thiourea consumption could be attained when sodium sulphite was added.展开更多
For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, eva...For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, evaluating foods as sources of exposure to arsenic is important in assessing risk and developing strategies that protect public health. Although most emphasis has been placed on inorganic arsenic as human carcinogen and toxicant, an array of arsenic-containing species are found in plants and animals used as foods. Here,we 2evaluate the contribution of complex organic arsenicals（arsenosugars, arsenolipids,and trimethylarsonium compounds） that are found in foods and consider their origins,metabolism, and potential toxicity. Commonalities in the metabolism of arsenosugars and arsenolipids lead to the production of di-methylated arsenicals which are known to exert many toxic effects. Evaluating foods as sources of exposure to these complex organic arsenicals and understanding the formation of reactive metabolites may be critical in assessing their contribution to aggregate exposure to arsenic.展开更多
It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,...It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).展开更多
Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the...Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the formation of uranyl arsenate minerals have remained largely elusive.Herein,the formation pathway of the non-charged UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 complex was investigated to elucidate the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral(where n represents the stoichiometric number of H_(2)O),a representative uranyl arsenate mineral.Based on the combination experiments of U(VI)and As(V),our findings underscore the sig-nificant dependence of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 formation on solution pH(4.0–10.0).Density functional theory(DFT)calculations reveal a two-step reaction involving two distinct pathways(Pathway 1 and Pathway 2)for the formation of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O,and the intermediate was confirmed by in situ Raman and fluorescence spec-troscopy.Specifically,the hydroxyl‑connected uranyl(UO_(2)OH^(+))reacts with the protonated arsenate(H_(2)AsO_(4)^(-))species to form the intermediate UO_(2)HAsO4·H_(2)O(Pathway 1)or UO_(2)OH–H2AsO4(Pathway 2)with a U/As ratio of 1:1.Meanwhile,all the transition states also were obtained and the energy barrier suggested that the UO_(2)(H_(2)AsO_(4))_(2)·2H_(2)O0 formed by Pathway 1 is thermodynamically favored over Pathway 2,and may serve as the primary fundamental structural unit or precursor for the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral phase.Altogether,this study contributes to advancing the understanding of the formation of uranyl arsenate min-erals at the molecular scale and provides a theoretical basis for predicting and regulating uranium and arsenic mobilization in their coexisting environment.展开更多
Manganese(Mn)is widely used to control cadmium(Cd)and arsenic(As)uptake by rice,but the effects of different Mn forms and concentrations on Cd/As movement in the soil-rice system are unclear.The study investigated the...Manganese(Mn)is widely used to control cadmium(Cd)and arsenic(As)uptake by rice,but the effects of different Mn forms and concentrations on Cd/As movement in the soil-rice system are unclear.The study investigated the mechanisms by which three Mn compounds affected the accumulation of Cd/As in rice under different application rates.MnO2,MnSO4,and MnCO_(3) treatments significantly reduced grains Cd levels by 27.6%,30.2%,and 28.1%,respectively,while As levels were less consistently affected.Three forms of Mn fertilizers enhanced the conversion of exchangeable to carbonate bound-Cd,which closely related to the increase of soil pH.MnO_(2) and MnCO_(3) reduced Cd translocation by increasing Cd/As adsorption on iron plaques,and MnSO4 and MnCO_(3) decreased Cd translocation by boosting root SOD and Cys levels.Transcriptome analysis revealed that Mn^(2+) upregulated genes involved in the antioxidant defense system,limited Cd transport by enhancing OsABCC1 and OsHMA3 expression,and promoted As translocation by increasing OsLsi2 expression.Overall,different forms of Mn fertilizers effectively reduced Cd toxicity by fixing Cd in soil carbonate and iron plaques,and restricting Cd transport.Although Mn fertilizers reduced As availability in soil and affected As absorption in rice,they have certain limitations and need to be further explored.These findings reveal the mechanism by which different forms of Mn regulate the fixation and migration behavior of Cd and As,providing new ideas and theoretical basis for reducing the environmental risk of Cd and As.展开更多
Industrial activities have caused widespread arsenic(As)contamination in soil and medicinal crops across south-ern Asia.This study constructed interplanting systems combing medicinal crops with Pteris vittata L.,aimin...Industrial activities have caused widespread arsenic(As)contamination in soil and medicinal crops across south-ern Asia.This study constructed interplanting systems combing medicinal crops with Pteris vittata L.,aiming to mitigate the risk of As exposure in medicinal crops,while simultaneously achieving ecological remediation of contaminated soil.The results revealed that interplanting with P.vittata significantly enhanced the yield of Gynos-temma pentaphyllum by 31.90%(P<0.05)compared with monoculture systems.Under monoculture conditions,the As concentration in G.pentaphyllum leaves reached 2.34 mg/kg,exceeding the national food safety standard(GB2762–2017,2 mg/kg).However,interplanting with P.vittata effectively reduced the As concentration in G.pentaphyllum leaves to 1.82 mg/kg.Furthermore,the interplanting of P.vittata with Rhus chinensis significantly inhibited As translocation from belowground to aboveground tissues in R.chinensis.Compared to monoculture,the stem biomass of P.vittata was significantly increased by 57.50%and 70.32%when interplanted with G.pentaphyllum and Cassia obtusifolia L.(P<0.05).So the As enrichment of P.vittata was enhanced in interplanting systems,which is beneficial for the As removal from contaminated soil.The study demonstrated that interplant-ing primarily regulates plant As uptake through modifications of rhizosphere physicochemical properties and As bioavailability,especially for water-soluble As that is easily absorbed by plants.In conclusion,the interplant-ing models integrating medicinal crops and P.vittata can achieve the goal of“remediating while producing”in As-contaminated soil.展开更多
The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623−773 K and pressure ranges of 10−10000 Pa.The experimental results reveal that the evaporation rate...The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623−773 K and pressure ranges of 10−10000 Pa.The experimental results reveal that the evaporation rate increases with increasing temperature and decreasing pressure.Surface reaction control dominates at low pressures(<100 Pa),whereas diffusion control dominates at high pressures(>5000 Pa).The evaporation behavior is successfully described by an Arrhenius-type model for temperature dependence and Logistic model for pressure dependence.Key kinetic parameters,including the critical pressure,maximum evaporation rate and evaporation coefficient,were calculated.The evaporation coefficient varies between 0.010 and 0.223,and the critical pressures vary between 281 and 478 Pa with temperature.展开更多
This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The finding...This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The findings revealed that the addition of 5wt%CRCF yields optimal performance,with compressive strengths reaching approximately 1.83,12.59,and 42.81 MPa at 1,3,and 28 d,respectively.These values represented significant increases of 408.3%,10.0%,and 14.3%compared to the reference sample.The improvement was attributed to the synergistic effects of ultrafine CRCF particles acting as fillers and nucleation sites,as well as the high reactivity of silica gels,which promoted the formation of additional hydration gels.Microstructural analysis confirmed that CRCF addition refined pore structure,and enhanced the stiffness of C-S-H gels.Furthermore,CRCF served as a net CO_(2) sink,sequestering 0.268 kg CO_(2) per kilogram of CRCF and thereby reducing the carbon footprint of SSC.In addition,the feasibility of applying CRCF-modified SSC in cemented paste backfill(CPB)is highlighted,given the high cement-related carbon footprint of conventional CPB.When 5wt%CRCFmodified SSC was employed in CPB,its 3-d compressive strength attained over 70%of that of ordinary Portland cement(OPC),while the 28-d strength was comparable to that of OPC.The proposed binder thus provides a sustainable pathway for BW valorization,combining waste utilization,carbon sequestration,and improved engineering performance.展开更多
Excessive phosphorus and arsenic in water bodies not only destroy ecosystems but also pose a serious threat to human health.In this study,a series of Al-doped modified metal-organic frameworks(Zr-Al-MOF)were prepared ...Excessive phosphorus and arsenic in water bodies not only destroy ecosystems but also pose a serious threat to human health.In this study,a series of Al-doped modified metal-organic frameworks(Zr-Al-MOF)were prepared by solvothermal method,which achieved efficient removal of phosphate and arsenate in water.Due to the use of inexpensive Al salts,the material has a lower cost and is more economical.The molar ratio of metal salts,adsorption time,solution pH,initial concentration,temperature and coexisting anions were studied,and it was found that when the molar ratio of Zr:Al was 2,Zr-Al-MOF had the best adsorption performance for phosphate and arsenate,and the maximum adsorption capacity was 93.04 mg P/g and 173.83 mg As/g,respectively.It traps phosphate and arsenate at a fast reaction rate and can be recycled repeatedly.In addition,0.15 g/L of 2Zr-Al-MOF can effectively reduce the phosphate and arsenate content in the contaminated spring water samples of Yangzonghai Lake to the standard range of drinking water,which further confirms the application potential of 2Zr-Al-MOF.By FT-IR and XPS analysis,it was found that the adsorption mechanism was ligand exchange,electrostatic attraction and hydrogen bond formation.The theoretical calculation shows that the adsorption energy is negative,which indicates that 2Zr-Al-MOF is attractive to phosphate and arsenate,and the adsorption state is stable.The results show that 2Zr-Al-MOF is an effective phosphate and arsenate adsorbent and has broad application prospects in eutrophication water treatment.展开更多
Violet phosphorus,a recently explored layered elemental semiconductor,has attracted much attention due to its unique photoelectric,mechanical properties,and high hole mobility.Herein,violet arsenic phosphorus has for ...Violet phosphorus,a recently explored layered elemental semiconductor,has attracted much attention due to its unique photoelectric,mechanical properties,and high hole mobility.Herein,violet arsenic phosphorus has for the first time been synthesized by a molten lead method.The crystal structure of violet arsenic phosphorus(P^(83.4)As_(0.6),CSD-2408761)was determined by single crystal X-ray diffraction to have similar structure as that of violet phosphorus,where P12 is occupied by arsenic/phosphorus(As/P)atoms as mixed occupancy sites As1/P12.The arsenic substitution has been demonstrated to tune the band structure of violet phosphorus,switching p-type of violet phosphorus to high-performance n-type violet arsenic phosphorus.The effective electron mass along the<010>direction is significantly reduced from 1.792 to 0.515 m_(0)by arsenic substitution,resulting in an extremely high electron mobility of 2622.503 cm^(2)V^(-1)s^(-1).The field effect transistor built with P_(83.4)As_(0.6)nanosheets was measured to have a high electron mobility(137.06 cm^(2)V^(-1)s^(-1),61.2 nm),even under ambient conditions for 5 h,much higher than the hole mobility of violet phosphorene nanosheets(4.07 cm^(2)V^(-1)s^(-1),73.3 nm).This work provides a new idea for designing phosphorus-based materials for field effect transistors,giving significant potential in complementary metal-oxide-semiconductor applications.展开更多
In this study,synthetic wastewater containing 110μg/L arsenate(As(V)),0-20 mg/L fulvic acid(FA),and 0-12.3 mg/L phosphate was treated with 3 mg/L Fe3+.The mechanisms of FA and phosphate effects on As(V)removal by fer...In this study,synthetic wastewater containing 110μg/L arsenate(As(V)),0-20 mg/L fulvic acid(FA),and 0-12.3 mg/L phosphate was treated with 3 mg/L Fe3+.The mechanisms of FA and phosphate effects on As(V)removal by ferric chloride were determined using 0.22-10μm pore-size filtration,Zetasizer analysis,and in situ flow through cell ATR-FTIR.The results showed that up to 20mg/L FA had almost no effect on the solubility of ferric hydroxide precipitates and adsorption of As(V)by the precipitates.When FA concentration increased from 0 to 20 mg/L,the adsorption of FA led to higher negative zeta potential of the precipitates and the strong electrostatic repulsion between the precipitates decreased the particle size of ferric hydroxide flocs fromlarger than 10μmto smaller than 1μm.In the presence of 5-20 mg/L FA,46%-63%As(V)was adsorbed onto the flocs with particle size in the range of 0.45-1μm.On the other hand,phosphate did not affect the size of ferric hydroxide flocs and significantly increased the dissolved As(V)concentration because it competed with As(V)for adsorption sites on ferric hydroxide precipitates.The addition of 5mg/L cationic organic flocculant significantly reduced the effect of FA on As(V)removal,but did not reduce the effect of phosphate on As(V)removal.The findings of this study will help develop effective arsenic treatment techniques and predict the mobility of arsenic in the environment.展开更多
Arsenic(As)pollution seriously threatens human and ecological health.Microalgal cell wall and extracellular polymeric substances(EPS)are known to interactwith As,but their roles in the As resistance,accumulation and s...Arsenic(As)pollution seriously threatens human and ecological health.Microalgal cell wall and extracellular polymeric substances(EPS)are known to interactwith As,but their roles in the As resistance,accumulation and speciation inmicroalgae remain unclear.Here,we used two strains of Chlamydomonas reinhardtii,namely CC-125(wild type)and CC-503(cell walldeficientmutant),to examine the algal growth,EPS synthesis,As adsorption,absorption and transformation under 10–1000μg/L As(III)and As(V)treatments for 96 h.In both strains,the As absorption increased after the EPS removal,but the growth,As adsorption,and transformation of C.reinhardtii declined.The CC-125 strain was more tolerant to As stress and more efficient in EPS production,As accumulation,and redox transformation than CC-503,irrespective of EPS presence or absence.Three-dimension excitation-emission matrix(3DEEM)and attenuated total reflectance infrared spectroscopy(ATR-IR)analyses showed that As was bound with functional groups in the EPS and cell wall,such as-COOH,NH and-OH in proteins,polysaccharides and amino acids.Together,this study demonstrated that EPS and cell wall acted as barriers to lower the As uptake by C.reinhardtii.However,the cell wall mutant strain wasmore susceptible to As toxicity due to lower EPS induction and higher As absorption.展开更多
With the increasing severity of arsenic(As)pollution,quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the pr...With the increasing severity of arsenic(As)pollution,quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the precise control strategies.Taking the industrialintensive Jinsha River Basin as typical area,a two-dimensional hydrodynamic water quality model coupled with Soil andWater Assessment Tool(SWAT)model was developed to accurately simulate the watershed-scale distribution and transport of As in the terrestrial and aquatic environment at high spatial and temporal resolution.The effects of hydro-climate change,hydropower station construction and non-point source emissions on Aswere quantified based on the coupled model.The result indicated that higher As concentration areas mainly centralized in urban districts and concentration slowly decreased from upstream to downstream.Due to the enhanced rainfall,the As concentration was significantly higher during the rainy season than the dry season.Hydro-climate change and the construction of hydropower station not only affected the dissolved As concentration,but also affected the adsorption and desorption of As in sediment.Furthermore,As concentration increased with the input of non-point source pollution,with the maximum increase about 30%,resulting that non-point sources contributed important pollutant impacts to waterways.The coupled model used in pollutant behavior analysis is generalwith high potential application to predict and mitigate water pollution.展开更多
Arsenic and cadmium contamination frequently coexist in the real environment.However it remains a challenge for their simultaneous removal due to their distinct physicochemica properties at low cost.To this end,a cost...Arsenic and cadmium contamination frequently coexist in the real environment.However it remains a challenge for their simultaneous removal due to their distinct physicochemica properties at low cost.To this end,a cost-effective magnetic biochar adsorbent (ITBNa800was prepared using biomass waste and iron tailings slag.This composite adsorbent exhibits excellent performance in the simultaneous removal of aqueous As(Ⅴ) and Cd(Ⅱ) even at high concentrations with removal efficiencies of up to 99.98%and 96.04%,respectively.Electro static action,precipitation,and complexation were adsorption mechanisms.As(Ⅴ) and Cd(Ⅱ were synergistic and competitive adsorption.As(Ⅴ) removal was mainly due to physical and chemical adsorption,and 42.40%-58.59%of As(Ⅴ) had been converted to As(Ⅲ ).Cd(Ⅱ) re moval was mainly due to chemical adsorption.Iron oxide and aluminum oxide in ITBNa800were the keys to As(Ⅴ),As(Ⅲ ),and Cd(Ⅱ) adsorption.DFT calculations revealed iron oxide complex As(Ⅴ),As(Ⅲ ),and Cd(Ⅱ) molecular clusters through bidentate binuclear,bidentate binuclear,and monodentate binuclear pathways,respectively.Aluminum oxide complex Cd(Ⅱ) molecular cluster through a bidentate mononuclear pathway.We hope the ITBNa800adsorbent and its involved mechanism could offer inspiration in the simultaneous treat ment of As and Cd pollution.展开更多
The Qinghai-Tibet Plateau,with its high altitude and cold climate,is one of the most fragile ecological environments in China and is distinguished by its naturally elevated arsenic(As)levels in the soil,largely due to...The Qinghai-Tibet Plateau,with its high altitude and cold climate,is one of the most fragile ecological environments in China and is distinguished by its naturally elevated arsenic(As)levels in the soil,largely due to its rich mineral and geothermal resources.This review provides a comprehensive analysis of As content,focusing on its distribution,environmental migration,and transformation behavior across the plateau.The review further evaluates the distribution of As in different functional areas,revealing that geothermal fields(107.2 mg/kg),mining areas(53.8 mg/kg),and croplands(39.3 mg/kg)have the highest As concentrations,followed by river and lake sediments and adjacent areas(33.1 mg/kg).These elevated levels are primarily attributed to the presence of As-rich minerals,such as arsenopyrite and pyrite.Additionally,human activities,including mining and geothermal energy production,exacerbate the release of As into the environment.The review also highlights the role of localmicroorganisms,particularly those fromthe phyla Proteobacteria and Actinobacteria,which possess As metabolic genes that facilitate As translocation.Given the unique climatic conditions of the plateau,conventionalmethods for As controlmay not be fully effective.However,the review identifies promising remediation strategies that are environmentally adaptable,such as the use of local microorganisms,specific adsorbents,and integrated technologies,which offer potential solutions for managing and utilizing Ascontaminated soils on the plateau.展开更多
Arsenic(As)methylation in soils affects the environmental behavior of As,excessive accumulation of dimethylarsenate(DMA)in rice plants leads to straighthead disease and a serious drop in crop yield.Understanding the m...Arsenic(As)methylation in soils affects the environmental behavior of As,excessive accumulation of dimethylarsenate(DMA)in rice plants leads to straighthead disease and a serious drop in crop yield.Understanding the mobility and transformation of methylated arsenic in redox-changing paddy fields is crucial for food security.Here,soils including unarsenic contaminated(N-As),low-arsenic(L-As),medium-arsenic(M-As),and high-arsenic(H-As)soils were incubated under continuous anoxic,continuous oxic,and consecutive anoxic/oxic treatments respectively,to profile arsenic methylating process and microbial species involved in the As cycle.Under anoxic-oxic(A-O)treatment,methylated arsenic was significantly increased once oxygen was introduced into the incubation system.The methylated arsenic concentrations were up to 2-24 times higher than those in anoxic(A),oxic(O),and oxic-anoxic(O-A)treatments,under which arsenic was methylated slightly and then decreased in all four As concentration soils.In fact,the most plentiful arsenite S-adenosylmethionine methyltransferase genes(arsM)contributed to the increase in As methylation.Proteobacteria(40.8%-62.4%),Firmicutes(3.5%-15.7%),and Desulfobacterota(5.3%-13.3%)were the major microorganisms related to this process.These microbial increasedmarkedly and played more important roles after oxygen was introduced,indicating that they were potential keystone microbial groups for As methylation in the alternating anoxic(flooding)and oxic(drainage)environment.The novel findings provided newinsights into the reoxidation-driven arsenic methylation processes and the model could be used for further risk estimation in periodically flooded paddy fields.展开更多
Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily ...Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar.However,the influence of a specific property on As immobilization varies among different studies,and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge.To enhance immobilization efficiency and reduce labor and time costs,a machine learning(ML)model was employed to predict As immobilization efficiency before biochar application.In this study,we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models.The results demonstrated that the random forest(RF)model outperformed gradient boost regression tree and support vector regression models in predictive performance.Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization.These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils.Furthermore,the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization.These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency.展开更多
In this study,we investigated improving the performance of a layered double hydroxide(LDH)for the adsorption of As(III)and As(V)by controlling the morphology of LDH crystals.The LDH was synthesized via a simple coprec...In this study,we investigated improving the performance of a layered double hydroxide(LDH)for the adsorption of As(III)and As(V)by controlling the morphology of LDH crystals.The LDH was synthesized via a simple coprecipitation method using barely soluble MgO as a precursor and succinic acid(SA)as a morphological control agent.Doping the LDH crystals with carboxylate ions(RCOO−)derived from SA caused the crystals to develop in a radial direction.This changed the pore characteristics and increased the density of active surface sites.Subsequently,SA/MgFe-LDH showed excellent affinity for As(III)and As(V)with maximum sorption densities of 2.42 and 1.60 mmol/g,respectively.By comparison,the pristine MgFe-LDH had sorption capacities of 1.56 and 1.31 mmol/g for As(III)and As(V),respectively.The LDH was effective over a wide pH range for As(III)adsorption(pH 3-8.5)and As(V)adsorption(pH 3-6.5).Using a combination of spectroscopy and sorption modeling calculations,the main sorption mechanism of As(III)and As(V)on SA/MgFe-LDH was identified as inner-sphere complexation via ligand exchangewith hydroxyl group(-OH)and RCOO−.Specifically,bidentate As-Fe complexeswere proposed for both As(III)and As(V)uptake,with the magnitude of formation varying with the initial As concentration.Importantly,the As-laden adsorbent had satisfactory stability in simulated real landfill leachate.These findings demonstrate that SA/MgFe-LDH exhibits considerable potential for remediation of As-contaminated water.展开更多
基金sponsored by the National Natural Science Foundation of China (No. 91543103)
文摘Arsenic（As） is a notoriously toxic pollutant of health concern worldwide with potential risk of cancer induction, but meanwhile it is used as medicines for the treatment of different conditions including hematological cancers. Arsenic can undergo extensive metabolism in biological systems, and both toxicological and therapeutic effects of arsenic compounds are closely related to their metabolism. Recent studies have identified methylated thioarsenicals as a new class of arsenic metabolites in biological systems after exposure of inorganic and organic arsenicals, including arsenite, dimethylarsinic acid（DMAV）, dimethylarsinous glutathione（DMAIIIGS）, and arsenosugars. The increasing detection of thiolated arsenicals,including monomethylmonothioarsonic acid（MMMTAV）, dimethylmonothioarsinic acid（DMMTAV） and its glutathione conjugate（DMMTAVGS）, and dimethyldithioarsinic acid（DMDTAV） suggests that thioarsenicals may be important metabolites and play important roles in arsenic toxicity and therapeutic effects. Here we summarized the reported occurrence of thioarsenicals in biological systems, the possible formation pathways of thioarsenicals, and their toxicity, and discussed the biological implications of thioarsenicals on arsenic metabolism, toxicity, and therapeutic effects.
文摘The thiourea leaching of gold from the calcine of gold-bearing arsenical pyrite concentrate of Kangjiawan mine was studied.The effects of the leaching time,the concentrations of thiourea,hydrochloric acid and initial ferric ion on the leaching recovery of gold were investigated,and a regressive model has been established,which showed that the concentrations of thiourea and hydrochloric acid were the most important factors,leaching time the second,and concentration of the initial ferric ion the least・Under the optimal conditions,that is,temperature 50℃,the ratio of liquid to solid 4:1,thiourea 12g/L,hydrochloric acid 1 mol/L,and initial ferric ion 1 g/L,the leaching recoveries of gold and silver were more than 81%and 73%,respectively.The increase of silver recovery and the reduction of thiourea consumption could be attained when sodium sulphite was added.
文摘For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, evaluating foods as sources of exposure to arsenic is important in assessing risk and developing strategies that protect public health. Although most emphasis has been placed on inorganic arsenic as human carcinogen and toxicant, an array of arsenic-containing species are found in plants and animals used as foods. Here,we 2evaluate the contribution of complex organic arsenicals（arsenosugars, arsenolipids,and trimethylarsonium compounds） that are found in foods and consider their origins,metabolism, and potential toxicity. Commonalities in the metabolism of arsenosugars and arsenolipids lead to the production of di-methylated arsenicals which are known to exert many toxic effects. Evaluating foods as sources of exposure to these complex organic arsenicals and understanding the formation of reactive metabolites may be critical in assessing their contribution to aggregate exposure to arsenic.
文摘It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).
基金supported by the National Natural Science Foundation of China(Nos.U20A20267 and 22376223)Hunan Provincial Natural Science Foundation(No.2023JJ0065).
文摘Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the formation of uranyl arsenate minerals have remained largely elusive.Herein,the formation pathway of the non-charged UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 complex was investigated to elucidate the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral(where n represents the stoichiometric number of H_(2)O),a representative uranyl arsenate mineral.Based on the combination experiments of U(VI)and As(V),our findings underscore the sig-nificant dependence of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 formation on solution pH(4.0–10.0).Density functional theory(DFT)calculations reveal a two-step reaction involving two distinct pathways(Pathway 1 and Pathway 2)for the formation of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O,and the intermediate was confirmed by in situ Raman and fluorescence spec-troscopy.Specifically,the hydroxyl‑connected uranyl(UO_(2)OH^(+))reacts with the protonated arsenate(H_(2)AsO_(4)^(-))species to form the intermediate UO_(2)HAsO4·H_(2)O(Pathway 1)or UO_(2)OH–H2AsO4(Pathway 2)with a U/As ratio of 1:1.Meanwhile,all the transition states also were obtained and the energy barrier suggested that the UO_(2)(H_(2)AsO_(4))_(2)·2H_(2)O0 formed by Pathway 1 is thermodynamically favored over Pathway 2,and may serve as the primary fundamental structural unit or precursor for the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral phase.Altogether,this study contributes to advancing the understanding of the formation of uranyl arsenate min-erals at the molecular scale and provides a theoretical basis for predicting and regulating uranium and arsenic mobilization in their coexisting environment.
基金supported by the National Natural Science Foundation of China(No.42277032)Hunan Province science and technology innovation plan project(No.2023RC3203)Changsha Natural Science Foundation(No.kq2208246).
文摘Manganese(Mn)is widely used to control cadmium(Cd)and arsenic(As)uptake by rice,but the effects of different Mn forms and concentrations on Cd/As movement in the soil-rice system are unclear.The study investigated the mechanisms by which three Mn compounds affected the accumulation of Cd/As in rice under different application rates.MnO2,MnSO4,and MnCO_(3) treatments significantly reduced grains Cd levels by 27.6%,30.2%,and 28.1%,respectively,while As levels were less consistently affected.Three forms of Mn fertilizers enhanced the conversion of exchangeable to carbonate bound-Cd,which closely related to the increase of soil pH.MnO_(2) and MnCO_(3) reduced Cd translocation by increasing Cd/As adsorption on iron plaques,and MnSO4 and MnCO_(3) decreased Cd translocation by boosting root SOD and Cys levels.Transcriptome analysis revealed that Mn^(2+) upregulated genes involved in the antioxidant defense system,limited Cd transport by enhancing OsABCC1 and OsHMA3 expression,and promoted As translocation by increasing OsLsi2 expression.Overall,different forms of Mn fertilizers effectively reduced Cd toxicity by fixing Cd in soil carbonate and iron plaques,and restricting Cd transport.Although Mn fertilizers reduced As availability in soil and affected As absorption in rice,they have certain limitations and need to be further explored.These findings reveal the mechanism by which different forms of Mn regulate the fixation and migration behavior of Cd and As,providing new ideas and theoretical basis for reducing the environmental risk of Cd and As.
基金supported by the National Key Research and Development Program of China(No.2020YFC1807805)the Science and Technology Planning Project of Guangzhou,Guangdong Province,China(No.202206010176).
文摘Industrial activities have caused widespread arsenic(As)contamination in soil and medicinal crops across south-ern Asia.This study constructed interplanting systems combing medicinal crops with Pteris vittata L.,aiming to mitigate the risk of As exposure in medicinal crops,while simultaneously achieving ecological remediation of contaminated soil.The results revealed that interplanting with P.vittata significantly enhanced the yield of Gynos-temma pentaphyllum by 31.90%(P<0.05)compared with monoculture systems.Under monoculture conditions,the As concentration in G.pentaphyllum leaves reached 2.34 mg/kg,exceeding the national food safety standard(GB2762–2017,2 mg/kg).However,interplanting with P.vittata effectively reduced the As concentration in G.pentaphyllum leaves to 1.82 mg/kg.Furthermore,the interplanting of P.vittata with Rhus chinensis significantly inhibited As translocation from belowground to aboveground tissues in R.chinensis.Compared to monoculture,the stem biomass of P.vittata was significantly increased by 57.50%and 70.32%when interplanted with G.pentaphyllum and Cassia obtusifolia L.(P<0.05).So the As enrichment of P.vittata was enhanced in interplanting systems,which is beneficial for the As removal from contaminated soil.The study demonstrated that interplant-ing primarily regulates plant As uptake through modifications of rhizosphere physicochemical properties and As bioavailability,especially for water-soluble As that is easily absorbed by plants.In conclusion,the interplant-ing models integrating medicinal crops and P.vittata can achieve the goal of“remediating while producing”in As-contaminated soil.
基金Yunnan Fundamental Research Project,China(No.202201BE070001-056)。
文摘The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623−773 K and pressure ranges of 10−10000 Pa.The experimental results reveal that the evaporation rate increases with increasing temperature and decreasing pressure.Surface reaction control dominates at low pressures(<100 Pa),whereas diffusion control dominates at high pressures(>5000 Pa).The evaporation behavior is successfully described by an Arrhenius-type model for temperature dependence and Logistic model for pressure dependence.Key kinetic parameters,including the critical pressure,maximum evaporation rate and evaporation coefficient,were calculated.The evaporation coefficient varies between 0.010 and 0.223,and the critical pressures vary between 281 and 478 Pa with temperature.
基金supports from the National Natural Science Foundation of China(No.52304148)the Youth Project of Shanxi Basic Research Program(No.202203021212262).
文摘This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The findings revealed that the addition of 5wt%CRCF yields optimal performance,with compressive strengths reaching approximately 1.83,12.59,and 42.81 MPa at 1,3,and 28 d,respectively.These values represented significant increases of 408.3%,10.0%,and 14.3%compared to the reference sample.The improvement was attributed to the synergistic effects of ultrafine CRCF particles acting as fillers and nucleation sites,as well as the high reactivity of silica gels,which promoted the formation of additional hydration gels.Microstructural analysis confirmed that CRCF addition refined pore structure,and enhanced the stiffness of C-S-H gels.Furthermore,CRCF served as a net CO_(2) sink,sequestering 0.268 kg CO_(2) per kilogram of CRCF and thereby reducing the carbon footprint of SSC.In addition,the feasibility of applying CRCF-modified SSC in cemented paste backfill(CPB)is highlighted,given the high cement-related carbon footprint of conventional CPB.When 5wt%CRCFmodified SSC was employed in CPB,its 3-d compressive strength attained over 70%of that of ordinary Portland cement(OPC),while the 28-d strength was comparable to that of OPC.The proposed binder thus provides a sustainable pathway for BW valorization,combining waste utilization,carbon sequestration,and improved engineering performance.
基金supported by the NSFC-Yunnan Joint Fund(No.U2102210)the National Natural Science Foundation of China(No.22168044)+1 种基金Yunnan Provincial Department of Science and Technology(No.202201BF070001-013)the Research Innovation Fund for Graduate Students of Yunnan University(No.KC-23234004).
文摘Excessive phosphorus and arsenic in water bodies not only destroy ecosystems but also pose a serious threat to human health.In this study,a series of Al-doped modified metal-organic frameworks(Zr-Al-MOF)were prepared by solvothermal method,which achieved efficient removal of phosphate and arsenate in water.Due to the use of inexpensive Al salts,the material has a lower cost and is more economical.The molar ratio of metal salts,adsorption time,solution pH,initial concentration,temperature and coexisting anions were studied,and it was found that when the molar ratio of Zr:Al was 2,Zr-Al-MOF had the best adsorption performance for phosphate and arsenate,and the maximum adsorption capacity was 93.04 mg P/g and 173.83 mg As/g,respectively.It traps phosphate and arsenate at a fast reaction rate and can be recycled repeatedly.In addition,0.15 g/L of 2Zr-Al-MOF can effectively reduce the phosphate and arsenate content in the contaminated spring water samples of Yangzonghai Lake to the standard range of drinking water,which further confirms the application potential of 2Zr-Al-MOF.By FT-IR and XPS analysis,it was found that the adsorption mechanism was ligand exchange,electrostatic attraction and hydrogen bond formation.The theoretical calculation shows that the adsorption energy is negative,which indicates that 2Zr-Al-MOF is attractive to phosphate and arsenate,and the adsorption state is stable.The results show that 2Zr-Al-MOF is an effective phosphate and arsenate adsorbent and has broad application prospects in eutrophication water treatment.
基金supported by the National Natural Science Foundation of China(Grant No.22175136)the State Key Laboratory of Electrical Insulation and Power Equipment(Grant No.EIPE23127)the Fundamental Research Funds for the Central Universities(xtr052024009,xtr052025002).
文摘Violet phosphorus,a recently explored layered elemental semiconductor,has attracted much attention due to its unique photoelectric,mechanical properties,and high hole mobility.Herein,violet arsenic phosphorus has for the first time been synthesized by a molten lead method.The crystal structure of violet arsenic phosphorus(P^(83.4)As_(0.6),CSD-2408761)was determined by single crystal X-ray diffraction to have similar structure as that of violet phosphorus,where P12 is occupied by arsenic/phosphorus(As/P)atoms as mixed occupancy sites As1/P12.The arsenic substitution has been demonstrated to tune the band structure of violet phosphorus,switching p-type of violet phosphorus to high-performance n-type violet arsenic phosphorus.The effective electron mass along the<010>direction is significantly reduced from 1.792 to 0.515 m_(0)by arsenic substitution,resulting in an extremely high electron mobility of 2622.503 cm^(2)V^(-1)s^(-1).The field effect transistor built with P_(83.4)As_(0.6)nanosheets was measured to have a high electron mobility(137.06 cm^(2)V^(-1)s^(-1),61.2 nm),even under ambient conditions for 5 h,much higher than the hole mobility of violet phosphorene nanosheets(4.07 cm^(2)V^(-1)s^(-1),73.3 nm).This work provides a new idea for designing phosphorus-based materials for field effect transistors,giving significant potential in complementary metal-oxide-semiconductor applications.
基金financially supported by the New Jersey Department of Environmental ProtectionUS EPA。
文摘In this study,synthetic wastewater containing 110μg/L arsenate(As(V)),0-20 mg/L fulvic acid(FA),and 0-12.3 mg/L phosphate was treated with 3 mg/L Fe3+.The mechanisms of FA and phosphate effects on As(V)removal by ferric chloride were determined using 0.22-10μm pore-size filtration,Zetasizer analysis,and in situ flow through cell ATR-FTIR.The results showed that up to 20mg/L FA had almost no effect on the solubility of ferric hydroxide precipitates and adsorption of As(V)by the precipitates.When FA concentration increased from 0 to 20 mg/L,the adsorption of FA led to higher negative zeta potential of the precipitates and the strong electrostatic repulsion between the precipitates decreased the particle size of ferric hydroxide flocs fromlarger than 10μmto smaller than 1μm.In the presence of 5-20 mg/L FA,46%-63%As(V)was adsorbed onto the flocs with particle size in the range of 0.45-1μm.On the other hand,phosphate did not affect the size of ferric hydroxide flocs and significantly increased the dissolved As(V)concentration because it competed with As(V)for adsorption sites on ferric hydroxide precipitates.The addition of 5mg/L cationic organic flocculant significantly reduced the effect of FA on As(V)removal,but did not reduce the effect of phosphate on As(V)removal.The findings of this study will help develop effective arsenic treatment techniques and predict the mobility of arsenic in the environment.
基金supported by the National Natural Science Foundation of China(Nos.32171623 and 31770548)the National Key Research and Development Program of China(Nos.2016YFD0800306 and 2017YFD0800305).
文摘Arsenic(As)pollution seriously threatens human and ecological health.Microalgal cell wall and extracellular polymeric substances(EPS)are known to interactwith As,but their roles in the As resistance,accumulation and speciation inmicroalgae remain unclear.Here,we used two strains of Chlamydomonas reinhardtii,namely CC-125(wild type)and CC-503(cell walldeficientmutant),to examine the algal growth,EPS synthesis,As adsorption,absorption and transformation under 10–1000μg/L As(III)and As(V)treatments for 96 h.In both strains,the As absorption increased after the EPS removal,but the growth,As adsorption,and transformation of C.reinhardtii declined.The CC-125 strain was more tolerant to As stress and more efficient in EPS production,As accumulation,and redox transformation than CC-503,irrespective of EPS presence or absence.Three-dimension excitation-emission matrix(3DEEM)and attenuated total reflectance infrared spectroscopy(ATR-IR)analyses showed that As was bound with functional groups in the EPS and cell wall,such as-COOH,NH and-OH in proteins,polysaccharides and amino acids.Together,this study demonstrated that EPS and cell wall acted as barriers to lower the As uptake by C.reinhardtii.However,the cell wall mutant strain wasmore susceptible to As toxicity due to lower EPS induction and higher As absorption.
基金supported by the National Key Research and Development Program of China(No.2017YFC1502504)the National Natural Science Foundation of China(No.41877531).
文摘With the increasing severity of arsenic(As)pollution,quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the precise control strategies.Taking the industrialintensive Jinsha River Basin as typical area,a two-dimensional hydrodynamic water quality model coupled with Soil andWater Assessment Tool(SWAT)model was developed to accurately simulate the watershed-scale distribution and transport of As in the terrestrial and aquatic environment at high spatial and temporal resolution.The effects of hydro-climate change,hydropower station construction and non-point source emissions on Aswere quantified based on the coupled model.The result indicated that higher As concentration areas mainly centralized in urban districts and concentration slowly decreased from upstream to downstream.Due to the enhanced rainfall,the As concentration was significantly higher during the rainy season than the dry season.Hydro-climate change and the construction of hydropower station not only affected the dissolved As concentration,but also affected the adsorption and desorption of As in sediment.Furthermore,As concentration increased with the input of non-point source pollution,with the maximum increase about 30%,resulting that non-point sources contributed important pollutant impacts to waterways.The coupled model used in pollutant behavior analysis is generalwith high potential application to predict and mitigate water pollution.
基金supported by the National Natural Science Foundation of China(NSFC)grants(Nos.41473122,41173113,52261145693 and 22106028)the Ministry of Science and Technology of the People’s Republic of China(MOST)+1 种基金the Fundamental Research Funds for the Central Universities(FRF-TP-19-020A1)the Hundred Talents Program of the Chinese Academy of Sciences,and China Postdoctoral Science Foundation(No.2023M730216).
文摘Arsenic and cadmium contamination frequently coexist in the real environment.However it remains a challenge for their simultaneous removal due to their distinct physicochemica properties at low cost.To this end,a cost-effective magnetic biochar adsorbent (ITBNa800was prepared using biomass waste and iron tailings slag.This composite adsorbent exhibits excellent performance in the simultaneous removal of aqueous As(Ⅴ) and Cd(Ⅱ) even at high concentrations with removal efficiencies of up to 99.98%and 96.04%,respectively.Electro static action,precipitation,and complexation were adsorption mechanisms.As(Ⅴ) and Cd(Ⅱ were synergistic and competitive adsorption.As(Ⅴ) removal was mainly due to physical and chemical adsorption,and 42.40%-58.59%of As(Ⅴ) had been converted to As(Ⅲ ).Cd(Ⅱ) re moval was mainly due to chemical adsorption.Iron oxide and aluminum oxide in ITBNa800were the keys to As(Ⅴ),As(Ⅲ ),and Cd(Ⅱ) adsorption.DFT calculations revealed iron oxide complex As(Ⅴ),As(Ⅲ ),and Cd(Ⅱ) molecular clusters through bidentate binuclear,bidentate binuclear,and monodentate binuclear pathways,respectively.Aluminum oxide complex Cd(Ⅱ) molecular cluster through a bidentate mononuclear pathway.We hope the ITBNa800adsorbent and its involved mechanism could offer inspiration in the simultaneous treat ment of As and Cd pollution.
基金supported by the Central Public-interest Scientific Institution Basal Research Fund(No.Y2024QC29)the Central Public-interest Scientific Institution Basal Research Fund(Nos.2024-jbkyywf-lwj and 2024-jbkyywf-zyj).
文摘The Qinghai-Tibet Plateau,with its high altitude and cold climate,is one of the most fragile ecological environments in China and is distinguished by its naturally elevated arsenic(As)levels in the soil,largely due to its rich mineral and geothermal resources.This review provides a comprehensive analysis of As content,focusing on its distribution,environmental migration,and transformation behavior across the plateau.The review further evaluates the distribution of As in different functional areas,revealing that geothermal fields(107.2 mg/kg),mining areas(53.8 mg/kg),and croplands(39.3 mg/kg)have the highest As concentrations,followed by river and lake sediments and adjacent areas(33.1 mg/kg).These elevated levels are primarily attributed to the presence of As-rich minerals,such as arsenopyrite and pyrite.Additionally,human activities,including mining and geothermal energy production,exacerbate the release of As into the environment.The review also highlights the role of localmicroorganisms,particularly those fromthe phyla Proteobacteria and Actinobacteria,which possess As metabolic genes that facilitate As translocation.Given the unique climatic conditions of the plateau,conventionalmethods for As controlmay not be fully effective.However,the review identifies promising remediation strategies that are environmentally adaptable,such as the use of local microorganisms,specific adsorbents,and integrated technologies,which offer potential solutions for managing and utilizing Ascontaminated soils on the plateau.
基金supported by the Shandong Province Natural Science Foundation of Major Basic Research Program (No.ZR2020ZD34)the Key Projects of the National Natural Science Foundation of China (No.42230706)+3 种基金the National Natural Science Foundation of China (No.42307164)the China Postdoctoral Science Foundation (Nos.2023TQ0191 and 2023M732060)the Shandong Postdoctoral Science Foundation (No.SDBX2023041)and the Qingdao Postdoctoral Science Foundation (No.QDBSH20230202052).
文摘Arsenic(As)methylation in soils affects the environmental behavior of As,excessive accumulation of dimethylarsenate(DMA)in rice plants leads to straighthead disease and a serious drop in crop yield.Understanding the mobility and transformation of methylated arsenic in redox-changing paddy fields is crucial for food security.Here,soils including unarsenic contaminated(N-As),low-arsenic(L-As),medium-arsenic(M-As),and high-arsenic(H-As)soils were incubated under continuous anoxic,continuous oxic,and consecutive anoxic/oxic treatments respectively,to profile arsenic methylating process and microbial species involved in the As cycle.Under anoxic-oxic(A-O)treatment,methylated arsenic was significantly increased once oxygen was introduced into the incubation system.The methylated arsenic concentrations were up to 2-24 times higher than those in anoxic(A),oxic(O),and oxic-anoxic(O-A)treatments,under which arsenic was methylated slightly and then decreased in all four As concentration soils.In fact,the most plentiful arsenite S-adenosylmethionine methyltransferase genes(arsM)contributed to the increase in As methylation.Proteobacteria(40.8%-62.4%),Firmicutes(3.5%-15.7%),and Desulfobacterota(5.3%-13.3%)were the major microorganisms related to this process.These microbial increasedmarkedly and played more important roles after oxygen was introduced,indicating that they were potential keystone microbial groups for As methylation in the alternating anoxic(flooding)and oxic(drainage)environment.The novel findings provided newinsights into the reoxidation-driven arsenic methylation processes and the model could be used for further risk estimation in periodically flooded paddy fields.
基金supported by the National Key Research and Development Program of China(No.2020YFC1808701).
文摘Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar.However,the influence of a specific property on As immobilization varies among different studies,and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge.To enhance immobilization efficiency and reduce labor and time costs,a machine learning(ML)model was employed to predict As immobilization efficiency before biochar application.In this study,we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models.The results demonstrated that the random forest(RF)model outperformed gradient boost regression tree and support vector regression models in predictive performance.Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization.These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils.Furthermore,the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization.These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency.
文摘In this study,we investigated improving the performance of a layered double hydroxide(LDH)for the adsorption of As(III)and As(V)by controlling the morphology of LDH crystals.The LDH was synthesized via a simple coprecipitation method using barely soluble MgO as a precursor and succinic acid(SA)as a morphological control agent.Doping the LDH crystals with carboxylate ions(RCOO−)derived from SA caused the crystals to develop in a radial direction.This changed the pore characteristics and increased the density of active surface sites.Subsequently,SA/MgFe-LDH showed excellent affinity for As(III)and As(V)with maximum sorption densities of 2.42 and 1.60 mmol/g,respectively.By comparison,the pristine MgFe-LDH had sorption capacities of 1.56 and 1.31 mmol/g for As(III)and As(V),respectively.The LDH was effective over a wide pH range for As(III)adsorption(pH 3-8.5)and As(V)adsorption(pH 3-6.5).Using a combination of spectroscopy and sorption modeling calculations,the main sorption mechanism of As(III)and As(V)on SA/MgFe-LDH was identified as inner-sphere complexation via ligand exchangewith hydroxyl group(-OH)and RCOO−.Specifically,bidentate As-Fe complexeswere proposed for both As(III)and As(V)uptake,with the magnitude of formation varying with the initial As concentration.Importantly,the As-laden adsorbent had satisfactory stability in simulated real landfill leachate.These findings demonstrate that SA/MgFe-LDH exhibits considerable potential for remediation of As-contaminated water.
