Metalloid arsenic(As)is not a necessary element for plants,but its excessive accumulation is toxic to plants,and it also poses a great health risk to humans via the food chain.Plants absorb and metabolize As through a...Metalloid arsenic(As)is not a necessary element for plants,but its excessive accumulation is toxic to plants,and it also poses a great health risk to humans via the food chain.Plants absorb and metabolize As through a variety of processes.Arsenate in the form of As^(5+)is absorbed by phosphate transporters,but methylated As and As^(3+)enter plant tissues mainly through aquaporin channels.Various strategies and practices have been proposed and applied to alleviate As toxicity or reduce As accumulation in plants,but an efficient and environment-friendly approach has yet to be developed.This review comprehensively explores As sources and uptake mechanisms,as well as the interactions of phosphorus(P)and As in their uptake,transportation and influences on plant growth and physiological activities.This comprehensive review covers the transport,metabolism,and tolerance processes that plants exhibit in response to As stress and the addition of P.In addition,we also present recent advances in reducing As toxicity and accumulation by improving P nutrition,manipulating P transporter genes and optimizing the plant microbial community.Finally,the future research directions and main challenges are briefly discussed.展开更多
In rice systems under continuous flooding(CF)irrigation,rice grains with high arsenic(As)concentration can be produced.In Argentina,these areas are located in the south of Corrientes Province and the north of Entre R&...In rice systems under continuous flooding(CF)irrigation,rice grains with high arsenic(As)concentration can be produced.In Argentina,these areas are located in the south of Corrientes Province and the north of Entre Ríos Province.The combination of agronomic management,genetic variability of rice varieties,and the characteristics of soil and irrigation water determines the concentration and proportion of grain As species.In this study,we evaluated two factors affecting grain As accumulation:irrigation management,CF and interrupted flooding(IF),and rice variety,rice with medium,long,and double long/wide grains.The experiments were conducted during four cropping cycles(2015–2016,2016–2017,2017–2018,and 2020–2021)on a farm in the north of Entre Ríos Province.Total As concentration in husked grains showed a wide range and was mostly above 0.30 mg kg^(-1),even after the polishing process.Fortunately,organic As was the predominant species.In polished rice,inorganic As concentration ranged between 0.02 and 0.28 mg kg^(-1).Significant differences were observed in grain As concentration between four rice varieties,with the highest inorganic and total As concentrations in grains of the medium-grain variety.The interaction of rice variety by irrigation management did not affect grain yield,but significantly reduced total As concentration in grains.Soil drainage under IF explained 43%–46%of the reduction of total As concentration in grains.The management practices of irrigation and rice variety had slight effects on inorganic As concentration in grains.In conclusion,a single soil drying period combined with proper rice varieties can be an effective management practice for mitigating As accumulation in rice grains.展开更多
Siderite tailings is a potentially cost-free iron(Fe)source for arsenic(As)fixation in hazardous arsenic-calcium residues(ACR)as stable scorodite.In this study,a pure siderite reagent was employed to investigate the m...Siderite tailings is a potentially cost-free iron(Fe)source for arsenic(As)fixation in hazardous arsenic-calcium residues(ACR)as stable scorodite.In this study,a pure siderite reagent was employed to investigate the mechanism and optimal conditions for As fixation in ACR via scorodite formation,while the waste siderite tailings were used to further demonstrate the cotreatment method.The cotreatment method starts with an introduction of sulfuric acid to the ACR for As extraction and gypsum precipitation,and is followed by the addition of H_(2)O_(2) to oxidize As(Ⅲ)in the extraction solutions and finalized by adding siderite with continuous air injection for scorodite formation.The dissolution-oxidation of siderite can slowly produce Fe(Ⅲ)to control aqueous As(V)-Fe(Ⅲ)precipitation supersaturation for continuous scorodite crystallization.Chemical analyses show that the extraction efficiency of As from the ACR reaches 94.55%,while the precipitation yield of extracted As via scorodite formation arrives at 99.63% and 99.47%,leading to fixation efficiency of 94.20% and 94.04% in terms of the total As in the ACR by using siderite reagent and tailings,respectively.The final solid products show desirable TCLP stability and long-term stability,meeting the requirement for safe storage(GB 5085.3-2007).XRD,FTIR,and TEM results reveal that such high stability is attributable to the formation of scorodite and the surface adsorption of As on the raw siderite and secondary maghemite.This innovative and economical application of siderite tailings for the treatment of hazardous ACR can be extended to the management of hydrometallurgical wastes.展开更多
Electrochemical conversion of hypertoxic trivalent arsenic to value-added metallic arsenic can not only contribute to pollution abatement,but also resources reutilization,therefore being widely explored.Electrochemica...Electrochemical conversion of hypertoxic trivalent arsenic to value-added metallic arsenic can not only contribute to pollution abatement,but also resources reutilization,therefore being widely explored.Electrochemical reduction of trivalent arsenic as a promising way is widely explored.However,the high efficiency conversion is retarded by the sluggish reduction kinetics of AsO33−and fierce evolution of side products of both H_(2)and toxic AsH_(3).Herein,by using the sodium citrate as the additive,the current efficiency for metal arsenic production is increased greatly from 60%to 91%,with the accompanied evolution of hypertoxic AsH_(3)being restrained from 0.15 Nm^(3)/t_(As)to 0.022 Nm^(3)/t_(As),promising a high-efficiency and green process.The electrochemical tests and electrode surface characterizations aswell as DFT calculations indicate that the added sodium citrate promotes both the diffusion of reactive AsO_(3)^(3−)towards the cathode and its subsequent adsorption on the Ti cathode,contributing to smoother reduction for generating metal arsenic,with the evolution of toxic AsH_(3)being hindered at the same time.The results can provide new insights for the highefficiency and greener conversion of hypertoxic trivalent arsenic to value-added metallic arsenic.展开更多
Water leaching of As2O3 from metallurgical dust containing various metals was investigated,serving the purpose of dearsenization and simultaneous metal enrichment especially for indium.Effects of leaching temperature,...Water leaching of As2O3 from metallurgical dust containing various metals was investigated,serving the purpose of dearsenization and simultaneous metal enrichment especially for indium.Effects of leaching temperature,liquid/solid ratio(LSR)and leaching time were studied.It was found that the initial dissolution was very fast but was then so inhibited by the increasingly dissolved As2O3,which makes it difficult to saturate enough arsenic in the leaching solution or in leaching out all the soluble arsenic with excess dosage of water within acceptable time(120 min).Only about 73%of As2O3 was extracted under the optimal conditions investigated.Two-step leaching showed similar trends and was thus unnecessary for improving As2O3 extraction.These observations could reasonably be accounted for the reversibility of the dissolution reaction.Kinetically,the leaching was described satisfactorily by the semi-empirical Avrami model with the apparent activation energy of 36.08 kJ/mol.The purity of the obtained product As2O3 could reach 98.7%,while the indium could be enriched in the leaching residue without loss.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
We report here arsenic speciation in 1643 freshwater fish samples,representing 14 common fish species from 53 waterbodies in Alberta,Canada.Arsenic species were extracted from fish muscle tissue.Arsenic species in the...We report here arsenic speciation in 1643 freshwater fish samples,representing 14 common fish species from 53 waterbodies in Alberta,Canada.Arsenic species were extracted from fish muscle tissue.Arsenic species in the extracts were separated using anion-exchange high-performance liquid chromatography(HPLC)and quantified using inductively coupled plasma mass spectrometry(ICPMS).The total arsenic concentrations in fish ranged from 2.8 to 1200μg/kg(in wet weight of sample)(mean 71±101μg/kg),which are all below the 2000μg/kg(wet weight)maximum allowable total arsenic in fish,recommended by the Ontario Ministry of the Environment.In 99.7%,or 1638 of all 1643 freshwater fish samples analyzed,arsenobetaine(AsB)was detectable,with concentrations higher than the method detection limit of 0.25μg/kg(wet weight).Dimethylarsinic acid(DMA)was detectable(concentration>0.25μg/kg)in 92.1%,or 1514 of the 1643 freshwater fish samples.Inorganic arsenate(iAs^(Ⅴ))was detectable(>0.25μg/kg)in 1119 fish(i.e.,68.1% of 1643 samples).Monomethylarsonic acid(MMA)was detectable(>0.25μg/kg)in 418 fish(25.4%of 1643 samples).The concentrations of arsenic species in the 1643 fish samples varied by as much as three orders of magnitude,ranging from below the method detection limit of 0.25μg/kg to the maximum concentrations of 380μg/kg for AsB,150μg/kg for DMA,70μg/kg for iAs^(Ⅴ),and 51μg/kg for MMA.AsB made up 46.1%±26.2% of total arsenic species.Arsenic speciation patterns varied between lake whitefish,northern pike,and walleye,the three most common types of fish analyzed.The relative proportion of DMA in northern pike was larger than in lake whitefish and walleye,and conversely,the relative proportion of iAs^(Ⅴ) was lower in northern pike.Seven unknown arsenic species were detected,and their chromatographic retention time did not match with those of available arsenic standards.At least one unknown arsenic species was detected in 33.4%,or 549 of 1643 freshwater fish samples.The concentrations of unknown arsenic species were as high as 61μg/kg.Future research is necessary to identify unknown arsenic species and to determine contributing factors to the observed arsenic species patterns and concentrations.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
Rapid screening of inorganic arsenic(iAs)in groundwater used for drinking by hundreds of millions of mostly rural residents worldwide is crucial for health protection.Most commercial field test kits are based on the G...Rapid screening of inorganic arsenic(iAs)in groundwater used for drinking by hundreds of millions of mostly rural residents worldwide is crucial for health protection.Most commercial field test kits are based on the Gutzeit reaction that uses mercury-based reagents for color development,an environmental concern that increasingly limits its utilization.This study further improves the Molybdenum Blue(MB)colorimetric method to allow for faster screening with more stable reagents.More importantly,a portable three-channel colorimeter is developed for screening iAs relative to the WHO drinking water guideline value(10μg/L).Adding the reducing reagents in sequence not only prolongs the storage time to>7 days,but also accelerates the color development time to 6 min in conjunction with lowering the H_(2)SO_(4) concentration in chromogenic reagents.The optimal pH ranges from 1.2 to 1.3 and is achieved by acidifying groundwater to 1%(V/V)HCl.With detection limits of 3.7μg/L for inorganic arsenate(iAs(V))and 3.8μg/L for inorganic arsenite(iAs(Ⅲ)),testing groundwater with-10μg/L of As has a precision<20%.The method works well for a range of phosphate concentrations of 48-950μg/L(0.5-10μmol/L).Concentrations of total_iAs(6-300μg/L),iAs(V)(6-230μg/L)and iAs(Ⅲ)(0-170μg/L)for 14 groundwater samples from Yinchuan Plain,Pearl River Delta,and Jianghan Plain,are in excellent agreements(linear regression slope:0.969-1.029)with the benchmark methods.The improved chemistry here lays the foundation for the MB colorimetric method to become a commercially viable screening tool,with further engineering and design improvement of the colorimeter.展开更多
Arsenic-related oxidative stress and resultant diseases have attracted global concern,while longitudinal studies are scarce.To assess the relationship between arsenic exposure and systemic oxidative damage,we performe...Arsenic-related oxidative stress and resultant diseases have attracted global concern,while longitudinal studies are scarce.To assess the relationship between arsenic exposure and systemic oxidative damage,we performed two repeatedmeasures among 5236 observations(4067 participants)in theWuhan-Zhuhai cohort at the baseline and follow-up after 3 years.Urinary total arsenic,biomarkers of DNA oxidative damage(8-hydroxy-2-deoxyguanosine(8-OHdG)),lipid peroxidation(8-isoprostaglandin F2alpha(8-isoPGF2α)),and protein oxidative damage(protein carbonyls(PCO))were detected for all observations.Here we used linearmixed models to estimate the cross-sectional and longitudinal associations between arsenic exposure and oxidative damage.Exposure-response curves were constructed by utilizing the generalized additive mixed models with thin plate regressions.After adjusting for potential confounders,arsenic level was significantly and positively related to the levels of global oxidative damage and their annual increased rates in dose-response manners.In cross-sectional analyses,each 1%increase in arsenic levelwas associated with a 0.406%(95%confidence interval(CI):0.379%to 0.433%),0.360%(0.301%to 0.420%),and 0.079%(0.055%to 0.103%)increase in 8-isoPGF2α,8-OHdG,and PCO,respectively.More importantly,arsenic was further found to be associated with increased annual change rates of 8-isoPGF2α(β:0.147;95%CI:0.130 to 0.164),8-OHdG(0.155;0.118 to 0.192),and PCO(0.050;0.035 to 0.064)in the longitudinal analyses.Our study suggested that arsenic exposurewas not only positively related with global oxidative damage to lipid,DNA,and protein in cross-sectional analyses,but also associated with annual increased rates of these biomarkers in dose-dependent manners.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
Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We h...Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We hypothesized that Fe(oxyhydr)oxide(FeOOH)minerals precipitated in situ from indigenous Fe in groundwater may immobilize As,providing a solution for safely using As-contaminated groundwater in irrigation.To confirm this hypothesis and identify the controlling mechanisms,we comprehensively evaluated the transport,speciation changes,and immobilization of As and Fe in agricultural canals irrigated using As-contaminated groundwater.The efficiently removed As and Fe in the canals accumulated in shallow sediment rather than subsurface sediment.Linear combination fitting(LCF)analysis of X-ray absorption near edge spectroscopy(XANES)indicated that As(Ⅴ)was the dominant As species,followed by As(Ⅲ),and therewas no FeAsO_(4) precipitate.Sequential extraction revealed higher contents of amorphous FeOOH and associated As in shallower sediment than in the subsurface layer.Stoichiometric molar ratio calculations,SEM-EDS,FTIR,and fluorescence spectroscopy collectively demonstrated that the microbial reductive dissolution of amorphous FeOOH proceeded via reactive dissolved organic matter(DOM)consumption in subsurface anoxic porewater environment facilitating high labile As,whereas in surface sediment,the in situ-generated amorphous FeOOH was stable and strongly inhibited As release via adsorption.In summary,groundwater Fe^(2+)can efficiently precipitate in benthic surface sediment as abundant amorphous FeOOH,which immobilizes most of the dissolved As,protecting agricultural soil from contamination.This field research supports the critical roles of the phase and reactivity of in situ-generated FeOOH in As immobilization and provides new insight into the sustainable use of contaminated water.展开更多
Objective:Previous studies have demonstrated that the metals cadmium and arsenic exhibit estrogen-like effects and may influence the occurrence and development of gynecological tumors.This study aims to explore the as...Objective:Previous studies have demonstrated that the metals cadmium and arsenic exhibit estrogen-like effects and may influence the occurrence and development of gynecological tumors.This study aims to explore the association between urinary cadmium and arsenic levels and the prevalence of gynecologic cancers using data from the National Health and Nutrition Examination Survey(NHANES).Methods:Data from female participants in NHANES 2003—2018 were analyzed.Using R software,datasets(DEMO,BMX,etc.)were merged,and complete cases were retained by intersecting row names,yielding a total of 2999 participants.After applying strict exclusion criteria,2802 participants were included:83 with gynecologic cancer(cancer group)and 2719 without(control group).Demographic,reproductive health,and urinary cadmium and arsenic data were collected.Binary Logistic regression models were employed to assess associations between urinary cadmium and arsenic levels and gynecologic cancer risk.Results:High urinary cadmium and arsenic levels were risk factors for gynecologic cancers,with odds ratios(ORs)of 1.623(95%CI 1.217 to 2.166)and 1.003(95%CI 1.001 to 1.005),respectively.After propensity score matching(PSM),the trend remained;cadmium was still a statistically significant risk factor with an OR of 2.182(95%CI 1.343 to 3.545),while arsenic’s association,though not statistically significant,still trended toward risk(OR=1.004,95%CI 0.999 to 1.009).Subgroup analyses showed that both cadmium and arsenic were risk factors for ovarian cancer(OR=1.745,95%CI 1.178 to 2.586 and OR=1.005,95%CI 1.002 to 1.008,respectively);these associations persisted after PSM.Additionally,cadmium increased the risk of endometrial cancer(OR=1.617,95%CI 1.109 to 2.356).Conclusion:Exposure to cadmium and arsenic is associated with an increased risk of ovarian and endometrial cancers.These findings suggest that reducing environmental exposure to heavy metals such as cadmium and arsenic may help prevent certain gynecologic cancers.展开更多
Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across...Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across the copper mining,beneficiation,and smelting processes using a life-cycle approach,providing important insights for arsenic pollution prevention and the resource utilization of arsenic-bearing solid waste.The results show that the amount of As in waste rock,tailing and concentrate are 53483 t,86632 t,76162 t,respectively.After smelting treatment,the amount of arsenic in different types of solid waste,wastewater,waste gas and products are 76128 t,1 t,31 t and 2 t,respectively,and the proportion in arsenic sulfide slag is the highest(55%).The amount of emission to the environment is 32 t,accounting for only 0.04%of total amount.In the future,key considerations are to improve the resource utilization rate of arsenic-containing solid waste(tailing,smelting slag),especially arsenic sulfide slag,and to digest its environmental risk.展开更多
A process was proposed for removing and stabilizing arsenic(As) from anode slime. The anode slime with high arsenic concentration was pretreated by circular alkaline leaching process. Then, the arsenic in the leaching...A process was proposed for removing and stabilizing arsenic(As) from anode slime. The anode slime with high arsenic concentration was pretreated by circular alkaline leaching process. Then, the arsenic in the leaching solution can be further precipitated as a form of scorodite crystalline(FeAsO4·2H2O). In the precipitating arsenic reaction, in which ferrous ions were oxidized by air gas, the effects of acidity(p H), reaction temperature, air flow rate, initial concentration of arsenic and initial molar ratio of Fe(II) to As(V) on arsenic precipitation were investigated. The results showed that sufficiently stable crystal scorodite could be achieved under the condition of initial arsenic concentration of 10 g/L, pH 3.0-4.0, Fe/As molar ratio of 1.5, the temperature of 80-95 °C, and the air flow rate higher than 120 L/h. Under the optimal condition, more than 78% of arsenic could be precipitated as a form of scorodite crystalline. The As leaching concentration of the precipitates was less than 2.0 mg/L and the precipitates may be considered to be safe for disposal.展开更多
Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leac...Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leaching time and liquid-to-solid ratio on metals leaching efficiencies were investigated. The results show that the arsenic can be effectively separated from other metals under the optimum conditions of alkali/dust mass ratio of 0.5, sodium sulfide addition of 0.25 g/g, leaching temperature of 90 ℃, leaching time of 2 h, and liquid-to-solid ratio of 5：1 （mL/g）. Under these conditions, the average leaching efficiencies of arsenic, antimony, lead, tin and zinc are 92.75%, 11.68%, 0.31%, 29.75% and 36.85%, respectively. The NaOH-Na2S alkaline leaching process provides a simple and highly efficient way to remove arsenic from high-arsenic dust, leaving residue as a suitable lead resource.展开更多
The arsenic extraction from the arsenic-containing cobalt and nickel slag,which came from the purification process of zinc sulfate solution in a zinc smelting factory,was investigated.The alkaline leaching method was ...The arsenic extraction from the arsenic-containing cobalt and nickel slag,which came from the purification process of zinc sulfate solution in a zinc smelting factory,was investigated.The alkaline leaching method was proposed according to the mode of occurrence of arsenic in the slag and its amphoteric characteristic.The leaching experiments were conducted in the alkaline aqueous medium,with bubbling of oxygen into the solution,and the optimal conditions for leaching arsenic were determined.The results showed that the extraction rate of arsenic was maximized at 99.10%under the optimal conditions of temperature 140 ℃,NaOH concentration 150 g/L,oxygen partial pressure 0.5 MPa,and a liquid-to-solid ratio 5：1.Based on the solubilities of As2O5,ZnO and PbO in NaOH solution at 25 ℃,a method for the separation of As in the form of sodium arsenate salt from the arsenic-rich leachate via cooling crystallization was established,and the reaction medium could be fully recycled.The crystallization rate was confirmed to reach 88.9%（calculated on the basis of Na3AsO4） upon a direct cooling of the hot leachate down to room temperature.On the basis of redox potentials,the sodium arsenate solution could be further reduced by sulfur dioxide（SO2） gas to arsenite,at a reduction yield of 92%under the suitable conditions.Arsenic trioxide with regular octahedron shape could be prepared successfully from the reduced solution,and further recycled to the purification process to purify the zinc sulfate solution.Also,sodium arsenite solution obtained after the reduction of arsenate could be directly used to purify the zinc sulfate solution.Therefore,the technical scheme of alkaline leaching with pressured oxygen,cooling crystallization,arsenate reduction by SO2 gas,and arsenic trioxide preparation,provides an attractive approach to realize the resource utilization of arsenic-containing cobalt and nickel slag.展开更多
The species of arsenic in secondary zinc oxide generated from fuming furnace were investigated. The results revealed that there are mainly three types of secondary zinc oxide based on three arsenic species. The main p...The species of arsenic in secondary zinc oxide generated from fuming furnace were investigated. The results revealed that there are mainly three types of secondary zinc oxide based on three arsenic species. The main phase of As is As2O3 in type Ⅰ, zinc arsenite （Zn（AsO2）2） in type Ⅱ and lead arsenate （Pb（As206）, Pb4As2O9） in type Ⅲ, respectively. Selective leaching of zinc oxide of type Ⅱ was carried out. The leaching rate of As kept at 65%-70% with 30 g/L NaOH and L/S ratio of 3 at 20 ℃ for 1 h, while the losses of Pb and Zn were both below 1%.展开更多
基金supported by the Key Research Foundation of Science and Technology Department of Zhejiang Province,China(2021C02064-3)the Jiangsu Collaborative Innovation Center for Modern Crop Production,China。
文摘Metalloid arsenic(As)is not a necessary element for plants,but its excessive accumulation is toxic to plants,and it also poses a great health risk to humans via the food chain.Plants absorb and metabolize As through a variety of processes.Arsenate in the form of As^(5+)is absorbed by phosphate transporters,but methylated As and As^(3+)enter plant tissues mainly through aquaporin channels.Various strategies and practices have been proposed and applied to alleviate As toxicity or reduce As accumulation in plants,but an efficient and environment-friendly approach has yet to be developed.This review comprehensively explores As sources and uptake mechanisms,as well as the interactions of phosphorus(P)and As in their uptake,transportation and influences on plant growth and physiological activities.This comprehensive review covers the transport,metabolism,and tolerance processes that plants exhibit in response to As stress and the addition of P.In addition,we also present recent advances in reducing As toxicity and accumulation by improving P nutrition,manipulating P transporter genes and optimizing the plant microbial community.Finally,the future research directions and main challenges are briefly discussed.
基金the National Agency for the Promotion of Research,Technological Development and Innovation(Argentina)the National University of Entre Ríos(Argentina)+1 种基金the PROARROZ Foundation(Argentina)the company EBRO(Argentina)for the financial support of this research。
文摘In rice systems under continuous flooding(CF)irrigation,rice grains with high arsenic(As)concentration can be produced.In Argentina,these areas are located in the south of Corrientes Province and the north of Entre Ríos Province.The combination of agronomic management,genetic variability of rice varieties,and the characteristics of soil and irrigation water determines the concentration and proportion of grain As species.In this study,we evaluated two factors affecting grain As accumulation:irrigation management,CF and interrupted flooding(IF),and rice variety,rice with medium,long,and double long/wide grains.The experiments were conducted during four cropping cycles(2015–2016,2016–2017,2017–2018,and 2020–2021)on a farm in the north of Entre Ríos Province.Total As concentration in husked grains showed a wide range and was mostly above 0.30 mg kg^(-1),even after the polishing process.Fortunately,organic As was the predominant species.In polished rice,inorganic As concentration ranged between 0.02 and 0.28 mg kg^(-1).Significant differences were observed in grain As concentration between four rice varieties,with the highest inorganic and total As concentrations in grains of the medium-grain variety.The interaction of rice variety by irrigation management did not affect grain yield,but significantly reduced total As concentration in grains.Soil drainage under IF explained 43%–46%of the reduction of total As concentration in grains.The management practices of irrigation and rice variety had slight effects on inorganic As concentration in grains.In conclusion,a single soil drying period combined with proper rice varieties can be an effective management practice for mitigating As accumulation in rice grains.
基金supported by the National Natural Science Foundation of China(Nos.42207258 and 52270150)the Liaoning Provincial Natural Science Foundation Program Project(No.2022-BS-312)+1 种基金the Liaoning University of Technology Doctoral Research Start-up Fund Project(No.XB2021013)the Shenyang Youth Science and Technology Project(No.RC210166).
文摘Siderite tailings is a potentially cost-free iron(Fe)source for arsenic(As)fixation in hazardous arsenic-calcium residues(ACR)as stable scorodite.In this study,a pure siderite reagent was employed to investigate the mechanism and optimal conditions for As fixation in ACR via scorodite formation,while the waste siderite tailings were used to further demonstrate the cotreatment method.The cotreatment method starts with an introduction of sulfuric acid to the ACR for As extraction and gypsum precipitation,and is followed by the addition of H_(2)O_(2) to oxidize As(Ⅲ)in the extraction solutions and finalized by adding siderite with continuous air injection for scorodite formation.The dissolution-oxidation of siderite can slowly produce Fe(Ⅲ)to control aqueous As(V)-Fe(Ⅲ)precipitation supersaturation for continuous scorodite crystallization.Chemical analyses show that the extraction efficiency of As from the ACR reaches 94.55%,while the precipitation yield of extracted As via scorodite formation arrives at 99.63% and 99.47%,leading to fixation efficiency of 94.20% and 94.04% in terms of the total As in the ACR by using siderite reagent and tailings,respectively.The final solid products show desirable TCLP stability and long-term stability,meeting the requirement for safe storage(GB 5085.3-2007).XRD,FTIR,and TEM results reveal that such high stability is attributable to the formation of scorodite and the surface adsorption of As on the raw siderite and secondary maghemite.This innovative and economical application of siderite tailings for the treatment of hazardous ACR can be extended to the management of hydrometallurgical wastes.
基金supported by the Industrial Technology Innovation Program of IMAST(No.2023JSYD03005)the National Key Basic Research and Development Program(No.2022YFC3900801)+1 种基金Fujian Province University-Industry Cooperation Research Program(No.2023H6007)the National Natural Science Foundation(No.52274349)and Fujian Province Natural Science Foundation(No.2023J05024).
文摘Electrochemical conversion of hypertoxic trivalent arsenic to value-added metallic arsenic can not only contribute to pollution abatement,but also resources reutilization,therefore being widely explored.Electrochemical reduction of trivalent arsenic as a promising way is widely explored.However,the high efficiency conversion is retarded by the sluggish reduction kinetics of AsO33−and fierce evolution of side products of both H_(2)and toxic AsH_(3).Herein,by using the sodium citrate as the additive,the current efficiency for metal arsenic production is increased greatly from 60%to 91%,with the accompanied evolution of hypertoxic AsH_(3)being restrained from 0.15 Nm^(3)/t_(As)to 0.022 Nm^(3)/t_(As),promising a high-efficiency and green process.The electrochemical tests and electrode surface characterizations aswell as DFT calculations indicate that the added sodium citrate promotes both the diffusion of reactive AsO_(3)^(3−)towards the cathode and its subsequent adsorption on the Ti cathode,contributing to smoother reduction for generating metal arsenic,with the evolution of toxic AsH_(3)being hindered at the same time.The results can provide new insights for the highefficiency and greener conversion of hypertoxic trivalent arsenic to value-added metallic arsenic.
基金Project(51874356)supported by the National Natural Science Foundation of China
文摘Water leaching of As2O3 from metallurgical dust containing various metals was investigated,serving the purpose of dearsenization and simultaneous metal enrichment especially for indium.Effects of leaching temperature,liquid/solid ratio(LSR)and leaching time were studied.It was found that the initial dissolution was very fast but was then so inhibited by the increasingly dissolved As2O3,which makes it difficult to saturate enough arsenic in the leaching solution or in leaching out all the soluble arsenic with excess dosage of water within acceptable time(120 min).Only about 73%of As2O3 was extracted under the optimal conditions investigated.Two-step leaching showed similar trends and was thus unnecessary for improving As2O3 extraction.These observations could reasonably be accounted for the reversibility of the dissolution reaction.Kinetically,the leaching was described satisfactorily by the semi-empirical Avrami model with the apparent activation energy of 36.08 kJ/mol.The purity of the obtained product As2O3 could reach 98.7%,while the indium could be enriched in the leaching residue without loss.
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 Alberta Health,Alberta Innovates,the Canada Research Chairs program,the Canadian Institutes of Health Research,and the Natural Sciences and Engineering Research Council of Canada.
文摘We report here arsenic speciation in 1643 freshwater fish samples,representing 14 common fish species from 53 waterbodies in Alberta,Canada.Arsenic species were extracted from fish muscle tissue.Arsenic species in the extracts were separated using anion-exchange high-performance liquid chromatography(HPLC)and quantified using inductively coupled plasma mass spectrometry(ICPMS).The total arsenic concentrations in fish ranged from 2.8 to 1200μg/kg(in wet weight of sample)(mean 71±101μg/kg),which are all below the 2000μg/kg(wet weight)maximum allowable total arsenic in fish,recommended by the Ontario Ministry of the Environment.In 99.7%,or 1638 of all 1643 freshwater fish samples analyzed,arsenobetaine(AsB)was detectable,with concentrations higher than the method detection limit of 0.25μg/kg(wet weight).Dimethylarsinic acid(DMA)was detectable(concentration>0.25μg/kg)in 92.1%,or 1514 of the 1643 freshwater fish samples.Inorganic arsenate(iAs^(Ⅴ))was detectable(>0.25μg/kg)in 1119 fish(i.e.,68.1% of 1643 samples).Monomethylarsonic acid(MMA)was detectable(>0.25μg/kg)in 418 fish(25.4%of 1643 samples).The concentrations of arsenic species in the 1643 fish samples varied by as much as three orders of magnitude,ranging from below the method detection limit of 0.25μg/kg to the maximum concentrations of 380μg/kg for AsB,150μg/kg for DMA,70μg/kg for iAs^(Ⅴ),and 51μg/kg for MMA.AsB made up 46.1%±26.2% of total arsenic species.Arsenic speciation patterns varied between lake whitefish,northern pike,and walleye,the three most common types of fish analyzed.The relative proportion of DMA in northern pike was larger than in lake whitefish and walleye,and conversely,the relative proportion of iAs^(Ⅴ) was lower in northern pike.Seven unknown arsenic species were detected,and their chromatographic retention time did not match with those of available arsenic standards.At least one unknown arsenic species was detected in 33.4%,or 549 of 1643 freshwater fish samples.The concentrations of unknown arsenic species were as high as 61μg/kg.Future research is necessary to identify unknown arsenic species and to determine contributing factors to the observed arsenic species patterns and concentrations.
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the National Key R&D Program of China(No.2021YFA0715900)the National Natural Science Foundation of China(No.41831279)+2 种基金the Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks(No.ZDSYS20220606100604008)the Guangdong Province Bureau of Education(No.2020KCXTD006)the Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control(No.2023B1212060002).
文摘Rapid screening of inorganic arsenic(iAs)in groundwater used for drinking by hundreds of millions of mostly rural residents worldwide is crucial for health protection.Most commercial field test kits are based on the Gutzeit reaction that uses mercury-based reagents for color development,an environmental concern that increasingly limits its utilization.This study further improves the Molybdenum Blue(MB)colorimetric method to allow for faster screening with more stable reagents.More importantly,a portable three-channel colorimeter is developed for screening iAs relative to the WHO drinking water guideline value(10μg/L).Adding the reducing reagents in sequence not only prolongs the storage time to>7 days,but also accelerates the color development time to 6 min in conjunction with lowering the H_(2)SO_(4) concentration in chromogenic reagents.The optimal pH ranges from 1.2 to 1.3 and is achieved by acidifying groundwater to 1%(V/V)HCl.With detection limits of 3.7μg/L for inorganic arsenate(iAs(V))and 3.8μg/L for inorganic arsenite(iAs(Ⅲ)),testing groundwater with-10μg/L of As has a precision<20%.The method works well for a range of phosphate concentrations of 48-950μg/L(0.5-10μmol/L).Concentrations of total_iAs(6-300μg/L),iAs(V)(6-230μg/L)and iAs(Ⅲ)(0-170μg/L)for 14 groundwater samples from Yinchuan Plain,Pearl River Delta,and Jianghan Plain,are in excellent agreements(linear regression slope:0.969-1.029)with the benchmark methods.The improved chemistry here lays the foundation for the MB colorimetric method to become a commercially viable screening tool,with further engineering and design improvement of the colorimeter.
基金supported by the National Natural Science Foundation of China(Nos.82241088 and 82203996)the China Postdoctoral Science Foundation(Nos.2022T150230 and 2021M691131).
文摘Arsenic-related oxidative stress and resultant diseases have attracted global concern,while longitudinal studies are scarce.To assess the relationship between arsenic exposure and systemic oxidative damage,we performed two repeatedmeasures among 5236 observations(4067 participants)in theWuhan-Zhuhai cohort at the baseline and follow-up after 3 years.Urinary total arsenic,biomarkers of DNA oxidative damage(8-hydroxy-2-deoxyguanosine(8-OHdG)),lipid peroxidation(8-isoprostaglandin F2alpha(8-isoPGF2α)),and protein oxidative damage(protein carbonyls(PCO))were detected for all observations.Here we used linearmixed models to estimate the cross-sectional and longitudinal associations between arsenic exposure and oxidative damage.Exposure-response curves were constructed by utilizing the generalized additive mixed models with thin plate regressions.After adjusting for potential confounders,arsenic level was significantly and positively related to the levels of global oxidative damage and their annual increased rates in dose-response manners.In cross-sectional analyses,each 1%increase in arsenic levelwas associated with a 0.406%(95%confidence interval(CI):0.379%to 0.433%),0.360%(0.301%to 0.420%),and 0.079%(0.055%to 0.103%)increase in 8-isoPGF2α,8-OHdG,and PCO,respectively.More importantly,arsenic was further found to be associated with increased annual change rates of 8-isoPGF2α(β:0.147;95%CI:0.130 to 0.164),8-OHdG(0.155;0.118 to 0.192),and PCO(0.050;0.035 to 0.064)in the longitudinal analyses.Our study suggested that arsenic exposurewas not only positively related with global oxidative damage to lipid,DNA,and protein in cross-sectional analyses,but also associated with annual increased rates of these biomarkers in dose-dependent manners.
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.
基金supported by the National Natural Science Foundation of China(Nos.41830753,42277201,42377242,and 41977286)the Scientific Research Foundation of Guangzhou University(No.YJ2023027)the College Student Innovation and Entrepreneurship Training Program(No.S202311078057).
文摘Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We hypothesized that Fe(oxyhydr)oxide(FeOOH)minerals precipitated in situ from indigenous Fe in groundwater may immobilize As,providing a solution for safely using As-contaminated groundwater in irrigation.To confirm this hypothesis and identify the controlling mechanisms,we comprehensively evaluated the transport,speciation changes,and immobilization of As and Fe in agricultural canals irrigated using As-contaminated groundwater.The efficiently removed As and Fe in the canals accumulated in shallow sediment rather than subsurface sediment.Linear combination fitting(LCF)analysis of X-ray absorption near edge spectroscopy(XANES)indicated that As(Ⅴ)was the dominant As species,followed by As(Ⅲ),and therewas no FeAsO_(4) precipitate.Sequential extraction revealed higher contents of amorphous FeOOH and associated As in shallower sediment than in the subsurface layer.Stoichiometric molar ratio calculations,SEM-EDS,FTIR,and fluorescence spectroscopy collectively demonstrated that the microbial reductive dissolution of amorphous FeOOH proceeded via reactive dissolved organic matter(DOM)consumption in subsurface anoxic porewater environment facilitating high labile As,whereas in surface sediment,the in situ-generated amorphous FeOOH was stable and strongly inhibited As release via adsorption.In summary,groundwater Fe^(2+)can efficiently precipitate in benthic surface sediment as abundant amorphous FeOOH,which immobilizes most of the dissolved As,protecting agricultural soil from contamination.This field research supports the critical roles of the phase and reactivity of in situ-generated FeOOH in As immobilization and provides new insight into the sustainable use of contaminated water.
基金supported by the Science and Technology Innovation Program of Hunan Province,China(2020SK2073).
文摘Objective:Previous studies have demonstrated that the metals cadmium and arsenic exhibit estrogen-like effects and may influence the occurrence and development of gynecological tumors.This study aims to explore the association between urinary cadmium and arsenic levels and the prevalence of gynecologic cancers using data from the National Health and Nutrition Examination Survey(NHANES).Methods:Data from female participants in NHANES 2003—2018 were analyzed.Using R software,datasets(DEMO,BMX,etc.)were merged,and complete cases were retained by intersecting row names,yielding a total of 2999 participants.After applying strict exclusion criteria,2802 participants were included:83 with gynecologic cancer(cancer group)and 2719 without(control group).Demographic,reproductive health,and urinary cadmium and arsenic data were collected.Binary Logistic regression models were employed to assess associations between urinary cadmium and arsenic levels and gynecologic cancer risk.Results:High urinary cadmium and arsenic levels were risk factors for gynecologic cancers,with odds ratios(ORs)of 1.623(95%CI 1.217 to 2.166)and 1.003(95%CI 1.001 to 1.005),respectively.After propensity score matching(PSM),the trend remained;cadmium was still a statistically significant risk factor with an OR of 2.182(95%CI 1.343 to 3.545),while arsenic’s association,though not statistically significant,still trended toward risk(OR=1.004,95%CI 0.999 to 1.009).Subgroup analyses showed that both cadmium and arsenic were risk factors for ovarian cancer(OR=1.745,95%CI 1.178 to 2.586 and OR=1.005,95%CI 1.002 to 1.008,respectively);these associations persisted after PSM.Additionally,cadmium increased the risk of endometrial cancer(OR=1.617,95%CI 1.109 to 2.356).Conclusion:Exposure to cadmium and arsenic is associated with an increased risk of ovarian and endometrial cancers.These findings suggest that reducing environmental exposure to heavy metals such as cadmium and arsenic may help prevent certain gynecologic cancers.
文摘Copper smelting is the main source of arsenic pollution in the environment,and China is the largest country for copper smelting.Taking 2022 as an example,this study analyzes the distribution and fate of arsenic across the copper mining,beneficiation,and smelting processes using a life-cycle approach,providing important insights for arsenic pollution prevention and the resource utilization of arsenic-bearing solid waste.The results show that the amount of As in waste rock,tailing and concentrate are 53483 t,86632 t,76162 t,respectively.After smelting treatment,the amount of arsenic in different types of solid waste,wastewater,waste gas and products are 76128 t,1 t,31 t and 2 t,respectively,and the proportion in arsenic sulfide slag is the highest(55%).The amount of emission to the environment is 32 t,accounting for only 0.04%of total amount.In the future,key considerations are to improve the resource utilization rate of arsenic-containing solid waste(tailing,smelting slag),especially arsenic sulfide slag,and to digest its environmental risk.
基金Projects(51304251,51374237)supported by the National Natural Science Foundation of ChinaProject(201509050)supported by Special Program on Environmental Protection for Public Welfare,ChinaProjects(2012FJ1010,2014FJ1011)supported by the Key Projects of Science and Technology of Hunan Province,China
文摘A process was proposed for removing and stabilizing arsenic(As) from anode slime. The anode slime with high arsenic concentration was pretreated by circular alkaline leaching process. Then, the arsenic in the leaching solution can be further precipitated as a form of scorodite crystalline(FeAsO4·2H2O). In the precipitating arsenic reaction, in which ferrous ions were oxidized by air gas, the effects of acidity(p H), reaction temperature, air flow rate, initial concentration of arsenic and initial molar ratio of Fe(II) to As(V) on arsenic precipitation were investigated. The results showed that sufficiently stable crystal scorodite could be achieved under the condition of initial arsenic concentration of 10 g/L, pH 3.0-4.0, Fe/As molar ratio of 1.5, the temperature of 80-95 °C, and the air flow rate higher than 120 L/h. Under the optimal condition, more than 78% of arsenic could be precipitated as a form of scorodite crystalline. The As leaching concentration of the precipitates was less than 2.0 mg/L and the precipitates may be considered to be safe for disposal.
基金Project(2012AA04022)supported by the Scientific Research and Technology Development Project of Guangxi,China
文摘Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leaching time and liquid-to-solid ratio on metals leaching efficiencies were investigated. The results show that the arsenic can be effectively separated from other metals under the optimum conditions of alkali/dust mass ratio of 0.5, sodium sulfide addition of 0.25 g/g, leaching temperature of 90 ℃, leaching time of 2 h, and liquid-to-solid ratio of 5：1 （mL/g）. Under these conditions, the average leaching efficiencies of arsenic, antimony, lead, tin and zinc are 92.75%, 11.68%, 0.31%, 29.75% and 36.85%, respectively. The NaOH-Na2S alkaline leaching process provides a simple and highly efficient way to remove arsenic from high-arsenic dust, leaving residue as a suitable lead resource.
基金Project (2012BAC12B01) supported by the National Key Technologies R&D Program of ChinaProject (2012FJ1010) supported by Science and Technology Major Project of Hunan Province,China
文摘The arsenic extraction from the arsenic-containing cobalt and nickel slag,which came from the purification process of zinc sulfate solution in a zinc smelting factory,was investigated.The alkaline leaching method was proposed according to the mode of occurrence of arsenic in the slag and its amphoteric characteristic.The leaching experiments were conducted in the alkaline aqueous medium,with bubbling of oxygen into the solution,and the optimal conditions for leaching arsenic were determined.The results showed that the extraction rate of arsenic was maximized at 99.10%under the optimal conditions of temperature 140 ℃,NaOH concentration 150 g/L,oxygen partial pressure 0.5 MPa,and a liquid-to-solid ratio 5：1.Based on the solubilities of As2O5,ZnO and PbO in NaOH solution at 25 ℃,a method for the separation of As in the form of sodium arsenate salt from the arsenic-rich leachate via cooling crystallization was established,and the reaction medium could be fully recycled.The crystallization rate was confirmed to reach 88.9%（calculated on the basis of Na3AsO4） upon a direct cooling of the hot leachate down to room temperature.On the basis of redox potentials,the sodium arsenate solution could be further reduced by sulfur dioxide（SO2） gas to arsenite,at a reduction yield of 92%under the suitable conditions.Arsenic trioxide with regular octahedron shape could be prepared successfully from the reduced solution,and further recycled to the purification process to purify the zinc sulfate solution.Also,sodium arsenite solution obtained after the reduction of arsenate could be directly used to purify the zinc sulfate solution.Therefore,the technical scheme of alkaline leaching with pressured oxygen,cooling crystallization,arsenate reduction by SO2 gas,and arsenic trioxide preparation,provides an attractive approach to realize the resource utilization of arsenic-containing cobalt and nickel slag.
基金Project (50874121) supported by the National Natural Science Foundation of China
文摘The species of arsenic in secondary zinc oxide generated from fuming furnace were investigated. The results revealed that there are mainly three types of secondary zinc oxide based on three arsenic species. The main phase of As is As2O3 in type Ⅰ, zinc arsenite （Zn（AsO2）2） in type Ⅱ and lead arsenate （Pb（As206）, Pb4As2O9） in type Ⅲ, respectively. Selective leaching of zinc oxide of type Ⅱ was carried out. The leaching rate of As kept at 65%-70% with 30 g/L NaOH and L/S ratio of 3 at 20 ℃ for 1 h, while the losses of Pb and Zn were both below 1%.
