Objective To study the combined effect of fluoride and arsenate on the expression of SD rat osteoblastic osteoclast differentiation factor (ODF) mRNA and osteoprotegerin (OPG) mRNA. Methods Osteoblasts were obtain...Objective To study the combined effect of fluoride and arsenate on the expression of SD rat osteoblastic osteoclast differentiation factor (ODF) mRNA and osteoprotegerin (OPG) mRNA. Methods Osteoblasts were obtained by enzymatic isolation from newborn SD rats. A factorial experiment was performed. Osteoblasts were exposed to NaF (0.5 mmolF/L, 4 molF/L) and Na3AsH2 (12.5 μmolAs/L and 200 μmolAs/L) separately or F plus As and cultured for 48 h. The gene expression of osteoblastic ODF and OPG was observed by RT-PCR. Results The expression ofODF mRNA increased in F0.5, F4 groups compared with control group and two groups of F0.As200, F,As200 compared with As200 group, and decreased significantly in groups of F4As12.5, F0.5As200, and F4As200. The expression of OPG rnRNA decreased in groups of F4, As200, F4As12.5, F0.5As200, and F4As200. Conclusion The joint effect of fluoride and arsenate on the gene expression of ODF is antagonistic, while the combined effect on the gene expression of OPG is synergistic. F4, F4As12.5, and F0.5As200 promote bone resorption of rat osteoclasts, whereas F0.5As12.5 inhibits osteolytic effect of rat osteoclasts.展开更多
The fate of arsenic in natural environments is influenced by adsorption onto metal (hydr)oxides. The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids. Recently, some st...The fate of arsenic in natural environments is influenced by adsorption onto metal (hydr)oxides. The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids. Recently, some studies reported that there existed competitive adsorption between arsenate and citrate on goethite. Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution, hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another. The results showed that at the arsenate concentrations used in this study (0.006-0.27 mmol/L), citrate decreased arsenate adsorption at acidic pH but no effect was observed at alkaline pH. In comparison, citrate adsorption was inhibited at acidic pH, but enhanced at alkaline pH by arsenate. This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid. These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites, but the cooperation between the two species at the watergoethite interface as well.展开更多
Natural pyrites contain high levels of adsorbed and structurally incorporated arsenic(As),which may simultaneously result in the release of As and affect the oxidation process of pyrite.However,the oxidation and elect...Natural pyrites contain high levels of adsorbed and structurally incorporated arsenic(As),which may simultaneously result in the release of As and affect the oxidation process of pyrite.However,the oxidation and electrochemical behaviors of As on the oxidation reactivity of pyrites are still not clear.In this study,pyrite was prepared by a hydrothermal method and applied to study the oxidation mechanism between pyrite and aqueous arsenate.Analyses of X-ray diffraction,X-ray photoelectron spectroscopy,and scanning electron microscopy demonstrate that the as-prepared sample is an octahedron-like pyrite with high purity and crystallinity.The interaction between As(V)and pyrite as well as the electrochemical behaviors of pyrite oxidation in the presence of aqueous arsenate were investigated under acidic conditions by an ion analysis method,cyclic voltammetry(CV),Tafel,and electrochemical impedance spectroscopy(EIS).The results of the chemical reaction indicate that electrons are transferred from S 22-to dissolved oxygen with the formation of SO 42-in the initial As(V)concentration range of 0–0.3 mmol/L.In the initial As(V)concentration range of 0.4–1.2 mmol/L,electrons are transferred from S 22-to As(V)with the formation of elemental S 0 and As(III).The CV,the Tafel plot and EIS analyses indicate that aqueous arsenate in an electrolyte promotes oxidation reactivity and passivation of the pyrite electrode.Moreover,the electron transfer rate increases with increasing aqueous arsenate concentration in the electrolyte.展开更多
The AAAc(1 : 1) was synthesized in water by As2O3 and Sb2O3 with molar ratio of 1 : 1: AAAc(1 : 1)was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to vsof As-OH, As-...The AAAc(1 : 1) was synthesized in water by As2O3 and Sb2O3 with molar ratio of 1 : 1: AAAc(1 : 1)was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to vsof As-OH, As-O-Sb, Sb-OH and Sb-O-Sb in Raman spectra of AAAc(1 : 1) at 100 - 1 000 cm-1. The solution of AAAc(1 : 1) was also titrated with KOH solution. The titration results show that AAAc(1 : 1) is a hexabasic acid with dissociation constants of k1 = 3.62 × 10-2 , k2 = 3.05 × 10-3 , k3 = 6. 43 × 10-6 , k4 = 9. 78 × 10-8 ,k5 = 1.32 × 10-11 , k6 =3.87 × 10-12. AAAc(1 : 1) has a good solubility and stability in water, its solid obtained by free volatilizing water from its solution under air at ambient temperature is amorphous. Chemical and thermal analyture of AsO ( OH )2-OH-Sb ( OH )4-O-Sb ( OH )4-OH-AsO ( OH )2 or As ( OH )3-O-Sb(OH)4-O-Sb(OH)4-O-As(OH)3 (isomerism) through experimental determination and geometry optimization.展开更多
This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsena...This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsenate varies from 0.5 to 200 mg/l. A kinetic model was considered to describe the arsenates sorption on ZVI material. The kinetics of the arsenate sorption processes were described by the Langmuir kinetic model. The sorption capacity increases with high initial concentration which obtained the maximum sorption 2.1 mg/g at 200 mg/l of arsenate initial concentration. The results show that the rapid initial sorption rates of arsenate were occurred at the beginning of experiments running time, followed by a slower removal that gradually approaches an equilibrium condition. The data from laboratory batch experiments were used to verify the simulation results of the kinetic model resulting in good agreement between measured and modeled results. The results indicate that ZVI could be employed as sorbent materials to enhance the sorption processes and increase the removal rate of arsenate from water.展开更多
Arsenic(As)contamination in groundwater is a major problem in many countries,which causes serious health issues.In this paper,a novel method has been developed for the simultaneous removal of ROX and As(Ⅲ/Ⅴ)using th...Arsenic(As)contamination in groundwater is a major problem in many countries,which causes serious health issues.In this paper,a novel method has been developed for the simultaneous removal of ROX and As(Ⅲ/Ⅴ)using the modified sorghum straw biochar(MSSB).The MSSB was characterized by X-ray diffraction,scanning electron microscopy,Fourier Transform Infrared,and Brunauer–Emmet–Teller(BET)surface area.The removal performance of MSSB for ROX,arsenite[As(Ⅲ)],and arsenate(As(Ⅴ))was investigated using batch experiments.At pH of 5,the arsenic concentration of 1.0 mg/L,adsorbent dose of 1.0 g/L,the maximum adsorptioncapacities of ROX,As(Ⅲ),and As(Ⅴ)were 12.4,5.3,and 23.0 mg/g,respectively.The adsorption behaviors were fit well with the Langmuir and the pseudo-second-order rate model.The results showed that MSSB acted as a highly effective adsorbent to simultaneously remove the composite pollution system consisted of ROX and As(Ⅲ/Ⅴ)in aqueous solutions,providing a promising method in environmental restoration applications.展开更多
The adsorption characteristics of arsenate on ion exchange fiber(IEF) and iron-modified ion exchange fiber(FeIEF) were evaluated.Batch adsorption experiments were conducted to study the arsenate adsorption effect by v...The adsorption characteristics of arsenate on ion exchange fiber(IEF) and iron-modified ion exchange fiber(FeIEF) were evaluated.Batch adsorption experiments were conducted to study the arsenate adsorption effect by varying contact time,pH,and coexisting anions.Adsorption capacity was found to increase by increasing the contact time and acidic conditions were favorable for arsenate adsorption on IEF and Fe-IEF.Arsenate adsorption data were better consistent with Freundlich equation than Langmuir equation.The maximum monolayer adsorption capacities were 285 and 333 mg/g at 25℃ for IEF and Fe-IEF respectively.The adsorption kinetics was found to follow the pseudo-first-order kinetic model.The existence of HCO 3-,PO34-,SO24-,SiO23-,and NO 3-decreased the arsenate adsorption capacity on IEF.Cl-and F-had little influence on it.When FeIEF was adopted,the effects of HCO 3-,SO24-,Cl-,SiO23-,and NO 3-were negligible,while PO43-could still markedly decrease the adsorption capacity and F-had inhibitory effect on arsenate adsorption.Fe-IEF can be used as a highly selective and efficient sorbent for removal of arsenate from aqueous solutions.展开更多
One new arsenic-vanadium cluster, [Zn(dien)(Hdien)]2[As6V15O42(H2O)]·4H2O (1, dien = diethylenetriamine), has been hydrothermally synthesized and characterized by IR, elemental analysis, TGA, magnetic pro...One new arsenic-vanadium cluster, [Zn(dien)(Hdien)]2[As6V15O42(H2O)]·4H2O (1, dien = diethylenetriamine), has been hydrothermally synthesized and characterized by IR, elemental analysis, TGA, magnetic property and single-crystal X-ray diffraction analysis. Crystal data for 1: monoclinic, space group P21/n, a = 13.959(3), b = 22.428(5), c = 22.831(5) A^°, β = 90.733(4)°, Z = 4. X-ray crystallographic study showed that compound 1 is constructed from [As6V15O42(H2O)]^6- polyoxoanions linked together by novel [Zn(dien)(Hdien)]^3+ complex fragments via hydrogen bonds into a three-dimensional network. Variable temperature susceptibility measurement demonstrates the presence of antiferromagnetic interaction between V^IV cations in 1.展开更多
Three new polyoxometalates K2[H2(As3O3)2(Mo6O18)(NiO6)]?H2O (1), K2[H2-(As3O3)2(Mo6O18)(CoO6)]?H2O (2) and [Zn(H4,4?-bpy)2(H2O)4][(As3O3)2(Mo6O18)(ZnO6)]?4H2O (3) (4,4?-bpy = 4,4?-bi...Three new polyoxometalates K2[H2(As3O3)2(Mo6O18)(NiO6)]?H2O (1), K2[H2-(As3O3)2(Mo6O18)(CoO6)]?H2O (2) and [Zn(H4,4?-bpy)2(H2O)4][(As3O3)2(Mo6O18)(ZnO6)]?4H2O (3) (4,4?-bpy = 4,4?-bipyridine) have been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, XPS and single-crystal X-ray diffraction analyses, respectively. Compound 1 represents a new 3D framework structure constructed from polyoxoanion [(As3O3)2(Mo6O18)(NiO6)]4- via covalent bond. Compound 2 has an identical structure with 1. Compound 3 represents a new 2D layer structure constructed from transition metal coordination cations [Zn(H4,4?-bipy)2(H2O)4]4+, lattice water molecules and polyoxoanions [(As3O3)2- (Mo6O18)(ZnO6)]4- via multi-point N–H???O and O–H???O hydrogen bonding interactions. Crystal data: for 1, cubic, space group Pa-3, a = 15.0022(8) ?, V = 3376.5(3) ?3, Z = 24; for 2, cubic space group Pa-3, a = 15.1596(10), V = 3483.88 ?3, Z = 24; for 3, monoclinic, space group C2/m, a = 19.699(4), b = 14.223(3), c = 9.1455(18) ?, β = 106.80(3)o, V = 2453.0(9) ?3, Z = 8. In addition, the magnetic behaviors for compounds 1 and 2 have been investigated.展开更多
Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate m...Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate minerals with subordinate Cu-Pb arsenate minerals and minor Fe-Pb-Ba varieties. Based on their paragenesis these minerals may be divided into the following series: (1) the clinoclasite-olivenite-cornwallite- cornubite- debaoite- copper silicarsenate association, (2) the scorodite- carminite- beudan-tite-bayldonite- duftite association, and (3) the scorodite-Ba-bearing pharmacosiderite- dussertite association. Arsenate minerals are formed generally in the oxidized zone of the sulfide-type deposits which lie in thewarm, humid and rainy torrid-subtropical zone with pH=6-8 and contain large amounts of arsenopyrite andcarbonate rocks.展开更多
In the area of recycling of spent chromated copper arsenate (CCA)-treated wood, most studies to date have focused on methods of removing/extracting the residual preservative from the wood matrix. It is well recognized...In the area of recycling of spent chromated copper arsenate (CCA)-treated wood, most studies to date have focused on methods of removing/extracting the residual preservative from the wood matrix. It is well recognized that exposure of CCA-treated wood to an acid solution can reverse the CCA fixation process thereby converting the CCA elements into their water-soluble form. The economic viability of the process is enhanced because it can be integrated with other technologies and products (e.g., “green” spray foam insulation, etc.). The market for the “green” CCA is the same as for traditional CCA-the wood treating industry, principally utility poles and pilings. A market research study was conducted to determine the suitability of spent CCA-treated wood as a source for recycled, “green” CCA for manufacturing “green” spray-foam insulation. Specifically, we wanted to discern the attitudes and overall perspectives of buyers/sellers (i.e., utilities and wood treating companies) of CCA preservatives and treated wood products, disposal methods and costs for decommissioned CCA-treated wood, and understand perceptions of and willingness-to-pay for “green” CCA preservatives extracted from the technologies used in this research. Results show that 60% of wood preservative treating respondents and 60% of electric utility company respondents are somewhat or greatly interested in using out-of-service utility poles as feedstock for “green insulation” as part of a new potential business venture.展开更多
Microbial reduction of As(V)(i.e.,arsenate)plays an important role in arsenic(As)mobilization in aqueous environment.In this study,we investigated As(V)reduction characteristics of the bacteria enriched from the arsen...Microbial reduction of As(V)(i.e.,arsenate)plays an important role in arsenic(As)mobilization in aqueous environment.In this study,we investigated As(V)reduction characteristics of the bacteria enriched from the arsenic-contaminated soil at an abandoned smelter site.It was found that As(V)was completely reduced to As(III)(i.e.,arsenite)in 21 h.After 3-d incubation,a yellow solid was precipitated and the concentration of As(III)decreased sharply.After 150 h incubation,ca.65%of soluble arsenic was removed fro...展开更多
A pot experiment was conducted to investigate the effect of different arsenic (As) levels on maize (Zea mays L.) growth and As accumulation and species in different parts of maize plants,as a guideline for product...A pot experiment was conducted to investigate the effect of different arsenic (As) levels on maize (Zea mays L.) growth and As accumulation and species in different parts of maize plants,as a guideline for production of maize in As-polluted areas with the objective of preventing As from entering the food chain,and improving understanding of the mechanisms of effect of As on plant.Zhengdan 958 was grown at five As levels added to soil (0,12.5,25,50,and 100 mg kg^-1 As).As concentration in maize tissues increased in the order of grain〈stalk〈leaf〈〈root.The As concentration in maize grain exceeded the maximum permissible concentration of 0.7 mg kg^-1 in China at levels of 50 and 100 mg kg^-1.As species were presented in root,stalk,and grain,but organic As was the major As species identified in the grain.Maize plants were able to reduce arsenate to arsenite.Low As levels of 12.5 and 25 mg kg^-1 improved maize growth and grain nutrition quality,while high levels of As 50 or 100 mg kg^-1 inhibited them.Yield reduction at high As levels resulted mainly from reduced ear length,kernel number per row,and kernel weight.展开更多
In the present study, arsenate(As(V)) and phosphate(P(V)) interactions were investigated in growth, uptake and RNA content in yeast(Saccharomyces cerevisiae). Yeast grew slowly with As(V) concentrations in...In the present study, arsenate(As(V)) and phosphate(P(V)) interactions were investigated in growth, uptake and RNA content in yeast(Saccharomyces cerevisiae). Yeast grew slowly with As(V) concentrations increasing in the medium. However, the maximal population density was almost the same among different As(V) treatments. It was in the late log phase that yeast growth was aug- mented by low As(V), which was maybe due to the fact that methionine metabolism was stressed by vitamin B6 deprivation, so As(V) treatments did not affect maximal population density. However, with P (V) concentrations increasing, the maximal population density increased. Therefore, the maximal population density was determined by P (V) concentrations in the medium but not by As (V) concentrations in the medium. Ycflp(a tonoplast transpor) transports As(GS)3 into the vacuole, but arsenic(As) remaining in the thalli was 1.27% with As(V) exposure for 60 h, from which it can be speculated that the percentage of As transported into vacuole should be lower than 1.27%. However, the percentage of As pumped out of cell was 71.49% with As (V) exposure for 68 h. Although two pathways (extrusion and sequestration) were involved in As detoxification in yeast, the extrusion pathway played a major role in As detoxification. RNA content was the highest in the early-log phase and was reduced by As(V).展开更多
The influence of arsenate and phosphate on the growth and respiration of 21 days old seedlings in two cultivars of rice, viz., IR64 and Nayanmani was studied. As arsenate and phosphate are similar in their chemical co...The influence of arsenate and phosphate on the growth and respiration of 21 days old seedlings in two cultivars of rice, viz., IR64 and Nayanmani was studied. As arsenate and phosphate are similar in their chemical configuration and the latter is preferentially taken up by the phosphate transporters, it results in a competitive inhibition of arsenate uptake in presence of phosphate. Increasing concentrations of sodium arsenate (25 μM, 50 μM and 100 μM) hindered the growth in both the cultivars, with cv. IR64 being more severely affected than cv. Nayanmani. There was an elevation in the levels of organic acids measured in both the cultivars, accompanied by a reduction in the activities of the dehydrogenases of the TCA cycle, viz., pyruvate dehydrogenase, isocitrate dehydrogenase, succinate dehydrogenase and malate dedrogenase under arsenic treatment alone. Also, an elevation in the activities of citrate synthase and fumarase enzymes was noticed in both test seedlings with increasing concentrations of arsenic. These alterations were more prominent in cv. IR64 than in cv. Nayanmani. On joint application of phosphate along with arsenate, amelioration of the toxic effects of arsenate was observed to some extent, resulting in an overall revival of respiration leading to improved growth and metabolism.展开更多
A pot experiment was conducted to investigate the heavy metal accumulation in maize (Zea mays L.) plant grown in chromated copper arsenate (CCA) soil amended with treated composted sewage biosolid. The initial concent...A pot experiment was conducted to investigate the heavy metal accumulation in maize (Zea mays L.) plant grown in chromated copper arsenate (CCA) soil amended with treated composted sewage biosolid. The initial concentrations of chromium, copper, arsenate in the CCA soil and sewage biosolid were determined by atomic absorption spectrophotometer. These were found to be, in CCA soil: 365.8 ± 6.18, 109.22 ± 14.04, 28.22 ± 3.8 and in sewage biosolid: 35 ± 1.06, 1.0 ± 0.02, 0 mg·kg-1 respectively. The concentration of Cr, Cu and As determined in both the roots and shoots generally decreased with increase in percentage amendment concentration and number of days (20 and 40 days after planting). At 20 days, the total metal concentration ranges in roots were As (5.54 ± 0.03 - 6.69 ± 1.14), Cr (9.59 ± 0.02 - 13.22 ± 0.03), Cu (2.28 ± 0.06 - 4.53 ± 0.37) mg·kg-1 while at 40 days the values were As (5.60 ± 0.19 - 6.08 ± 0.01), Cr (9.47 ± 0.04 - 10.95 ± 0.09), Cu (3.94 ± 0.19 - 4.64 ± 0.07) mg·kg-1. For the shoot system, the concentrations of the metals at 20 days were As (5.28 ± 0.03 - 5.90 ± 0.13), Cr (9.30 ± 0.05 - 10.07 ± 0.06), Cu (3.64 ± 0.12 - 4.72 ± 0.15) mg/kg while at 40 days the values obtained were As (5.28 ± 0.03 - 5.9 ± 0.13), Cr (9.69 ± 0.14 - 10.07 ± 0.03), Cu (2.94 ± 0.72 - 4.53 ± 0.03) mg·kg-1. The roots accumulated the three heavy metals more than the shoot system at all treatments used. Concentration of arsenic, chromium and copper in the plants decreased with increasing percentage amendments. The results suggest relatively low bioavailability of the three metals in CCA soil treated with high percentages of sewage biosolid as an amendment.展开更多
Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well doc...Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well documented,while little is known regarding effects due to endophytic bacteria.An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil.P.putida ARS1 shows high tolerance to arsenite(As(Ⅲ))and arsenate(As(V)),and exhibits efficient As(V)reduction and As(Ⅲ)effux activities.When exposed to 0.6 mg/L As(V),As(V)in the medium was completely converted to As(Ⅲ)by P.putida ARS1 within 4 hr.Genome sequencing showed that P.putida ARS1 has two chromosomal arsenic resistance gene clusters(arsRCBH)that contribute to efficient As(V)reduction and As(Ⅲ)effux,and result in high resistance to arsenicals.Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation,which takes up As(Ⅲ)more efficiently than As(V).Co-culture of P.putida ARS1 and W.globosa enhanced arsenic accumulation in W.globosa by 69%,and resulted in 91%removal of arsenic(at initial concentration of 0.6 mg/L As(V))from water within 3 days.This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium.展开更多
Many investigations suggest that dissimilatory arsenate-respiring prokaryotes (DARPs) play a key role in stimulating reductive mobilization of As from solid phase into groundwater,but it is not clear how environmental...Many investigations suggest that dissimilatory arsenate-respiring prokaryotes (DARPs) play a key role in stimulating reductive mobilization of As from solid phase into groundwater,but it is not clear how environmental Mn(Ⅱ) affects the DARPs-mediated reductive mobilization of arsenic.To resolve this issue,we collected soil samples from a realgar tailingsaffected area.We found that there were diverse arsenate-respiratory reductase (arr) genes in the soils.The microbial communities had high arsenate-respiring activity,and were able to efficiently stimulate the reductive mobilization of As.Compared to the microcosms without Mn(Ⅱ),addition of 10 mmol/L Mn(Ⅱ) to the microcosms led to 23.99%-251.79% increases in the microbial mobilization of As,and led to 133.3%-239.2% increases in the abundances of arr genes.We further isolated a new cultivable DARP,Bacillus sp.F11,from the arseniccontaminated soils.It completely reduced 1 mmol/L As(V) in 5 days under the optimal reaction conditions.We further found that it was able to efficiently catalyze the reductive mobilization and release of As from the solid phase;the addition of 2 mmol/L Mn(Ⅱ) led to 98.49%-248.78% increases in the F11 cells-mediated reductive mobilization of As,and70.6%-104.4% increases in the arr gene abundances.These data suggest that environmental Mn(Ⅱ) markedly increased the DARPs-mediated reductive mobilization of As in arseniccontaminated soils.This work provided a new insight into the close association between the biogeochemical cycles of arsenic and manganese.展开更多
Little information is available on influences of the conversion of dissolved organic phosphorus(DOP) to inorganic phosphorus(IP) on algal growth and subsequent behaviors of arsenate(As(V)) in Microcystis aeruginosa(M....Little information is available on influences of the conversion of dissolved organic phosphorus(DOP) to inorganic phosphorus(IP) on algal growth and subsequent behaviors of arsenate(As(V)) in Microcystis aeruginosa(M. aeruginosa). In this study, the influences factors on the conversion of three typical DOP types including adenosine-5-triphosphate disodium salt(ATP), β-glycerophosphate sodium(βP) and D-glucose-6-phosphate disodium salt(GP)were investigated under different extracellular polymeric secretions(EPS) ratios from M.aeruginosa, and As(V) levels. Thus, algal growth, As(V) biotransformation and microcystins(MCs) release of M. aeruginosa were explored in the different converted DOP conditions compared with IP. Results showed that the three DOP to IP without EPS addition became in favor of algal growth during their conversion. Compared with IP, M. aeruginosa growth was thus facilitated in the three converted DOP conditions, subsequently resulting in potential algal bloom particularly at arsenic(As) contaminated water environment. Additionally, DOP after conversion could inhibit As accumulation in M. aeruginosa, thus intracellular As accumulation was lower in the converted DOP conditions than that in IP condition. As(V) biotransformation and MCs release in M. aeruginosa was impacted by different converted DOP with their different types. Specifically, DMA concentrations in media and As(III) ratios in algal cells were promoted in converted βP condition, indicating that the observed dissolved organic compositions from βP conversion could enhance As(V) reduction in M. aeruginosa and then accelerate DMA release. The obtained findings can provide better understanding of cyanobacteria blooms and As biotransformation in different DOP as the main phosphorus source.展开更多
Arsenic (As) is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide. Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in fres...Arsenic (As) is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide. Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in freshwater aquatic systems. Arsenic metabolism processes of this alga through arsenate reduction and sequent store and efflux were investigated. When supplied with 10 μmol/L arsenate, arsenic speciation analysis showed that arsenite concentration increased from 5.7 to 15.7 mg/kg dry weight during a 7-day period, accounting for 18%–24% of the total As in alga. When treated with different levels of arsenate (10, 20, 30, 40, 50 μmol/L) for 7 days, the arsenite concentration increased with increasing external arsenate concentrations, the proportion of arsenite was up to 23%–28% of the total As in alga. In efflux experiments, both arsenate and arsenite could be found in the efflux solutions. Additionally, the efflux of arsenate was more than that of arsenite. Furthermore, two arsenate reductase genes of C. reinhardtii (CrACR2s) were cloned and expressed in Escherichia coli strain WC3110 (?arsC) for the first time. The abilities of both CrACR2s genes to complement the arsenate- sensitive strain were examined. CrACR2.1 restored arsenate resistance at 0.8 mmol/L. However, CrACR2.2 showed much less ability to complement. The gene products were demonstrated to reduce arsenate to arsenite in vivo. In agreement with the complementation results, CrACR2.1 showed higher reduction ability than CrACR2.2, when treated with 0.4 mmol/L arsenate for 16 hr incubation.展开更多
文摘Objective To study the combined effect of fluoride and arsenate on the expression of SD rat osteoblastic osteoclast differentiation factor (ODF) mRNA and osteoprotegerin (OPG) mRNA. Methods Osteoblasts were obtained by enzymatic isolation from newborn SD rats. A factorial experiment was performed. Osteoblasts were exposed to NaF (0.5 mmolF/L, 4 molF/L) and Na3AsH2 (12.5 μmolAs/L and 200 μmolAs/L) separately or F plus As and cultured for 48 h. The gene expression of osteoblastic ODF and OPG was observed by RT-PCR. Results The expression ofODF mRNA increased in F0.5, F4 groups compared with control group and two groups of F0.As200, F,As200 compared with As200 group, and decreased significantly in groups of F4As12.5, F0.5As200, and F4As200. The expression of OPG rnRNA decreased in groups of F4, As200, F4As12.5, F0.5As200, and F4As200. Conclusion The joint effect of fluoride and arsenate on the gene expression of ODF is antagonistic, while the combined effect on the gene expression of OPG is synergistic. F4, F4As12.5, and F0.5As200 promote bone resorption of rat osteoclasts, whereas F0.5As12.5 inhibits osteolytic effect of rat osteoclasts.
基金supported by the National Natural Science Foundation of China (No. 40673079, 40773076).
文摘The fate of arsenic in natural environments is influenced by adsorption onto metal (hydr)oxides. The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids. Recently, some studies reported that there existed competitive adsorption between arsenate and citrate on goethite. Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution, hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another. The results showed that at the arsenate concentrations used in this study (0.006-0.27 mmol/L), citrate decreased arsenate adsorption at acidic pH but no effect was observed at alkaline pH. In comparison, citrate adsorption was inhibited at acidic pH, but enhanced at alkaline pH by arsenate. This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid. These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites, but the cooperation between the two species at the watergoethite interface as well.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFC0211500)the National Natural Science Foundation of China (Nos. 51878449+1 种基金 21806121 51508384)
文摘Natural pyrites contain high levels of adsorbed and structurally incorporated arsenic(As),which may simultaneously result in the release of As and affect the oxidation process of pyrite.However,the oxidation and electrochemical behaviors of As on the oxidation reactivity of pyrites are still not clear.In this study,pyrite was prepared by a hydrothermal method and applied to study the oxidation mechanism between pyrite and aqueous arsenate.Analyses of X-ray diffraction,X-ray photoelectron spectroscopy,and scanning electron microscopy demonstrate that the as-prepared sample is an octahedron-like pyrite with high purity and crystallinity.The interaction between As(V)and pyrite as well as the electrochemical behaviors of pyrite oxidation in the presence of aqueous arsenate were investigated under acidic conditions by an ion analysis method,cyclic voltammetry(CV),Tafel,and electrochemical impedance spectroscopy(EIS).The results of the chemical reaction indicate that electrons are transferred from S 22-to dissolved oxygen with the formation of SO 42-in the initial As(V)concentration range of 0–0.3 mmol/L.In the initial As(V)concentration range of 0.4–1.2 mmol/L,electrons are transferred from S 22-to As(V)with the formation of elemental S 0 and As(III).The CV,the Tafel plot and EIS analyses indicate that aqueous arsenate in an electrolyte promotes oxidation reactivity and passivation of the pyrite electrode.Moreover,the electron transfer rate increases with increasing aqueous arsenate concentration in the electrolyte.
基金Project(50274075) supported by the National Natural Science Foundation of China
文摘The AAAc(1 : 1) was synthesized in water by As2O3 and Sb2O3 with molar ratio of 1 : 1: AAAc(1 : 1)was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to vsof As-OH, As-O-Sb, Sb-OH and Sb-O-Sb in Raman spectra of AAAc(1 : 1) at 100 - 1 000 cm-1. The solution of AAAc(1 : 1) was also titrated with KOH solution. The titration results show that AAAc(1 : 1) is a hexabasic acid with dissociation constants of k1 = 3.62 × 10-2 , k2 = 3.05 × 10-3 , k3 = 6. 43 × 10-6 , k4 = 9. 78 × 10-8 ,k5 = 1.32 × 10-11 , k6 =3.87 × 10-12. AAAc(1 : 1) has a good solubility and stability in water, its solid obtained by free volatilizing water from its solution under air at ambient temperature is amorphous. Chemical and thermal analyture of AsO ( OH )2-OH-Sb ( OH )4-O-Sb ( OH )4-OH-AsO ( OH )2 or As ( OH )3-O-Sb(OH)4-O-Sb(OH)4-O-As(OH)3 (isomerism) through experimental determination and geometry optimization.
文摘This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsenate varies from 0.5 to 200 mg/l. A kinetic model was considered to describe the arsenates sorption on ZVI material. The kinetics of the arsenate sorption processes were described by the Langmuir kinetic model. The sorption capacity increases with high initial concentration which obtained the maximum sorption 2.1 mg/g at 200 mg/l of arsenate initial concentration. The results show that the rapid initial sorption rates of arsenate were occurred at the beginning of experiments running time, followed by a slower removal that gradually approaches an equilibrium condition. The data from laboratory batch experiments were used to verify the simulation results of the kinetic model resulting in good agreement between measured and modeled results. The results indicate that ZVI could be employed as sorbent materials to enhance the sorption processes and increase the removal rate of arsenate from water.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41773136 and41703129)Innovation Talent Support Project of Liaoning (Grant No.LR2017073)+1 种基金the National Key Rand D Program of China (No.2017YFD0800301)the basic research projects of Source-sink transformation of arsenic and roxarsone in sediments (XXLJ2019007)。
文摘Arsenic(As)contamination in groundwater is a major problem in many countries,which causes serious health issues.In this paper,a novel method has been developed for the simultaneous removal of ROX and As(Ⅲ/Ⅴ)using the modified sorghum straw biochar(MSSB).The MSSB was characterized by X-ray diffraction,scanning electron microscopy,Fourier Transform Infrared,and Brunauer–Emmet–Teller(BET)surface area.The removal performance of MSSB for ROX,arsenite[As(Ⅲ)],and arsenate(As(Ⅴ))was investigated using batch experiments.At pH of 5,the arsenic concentration of 1.0 mg/L,adsorbent dose of 1.0 g/L,the maximum adsorptioncapacities of ROX,As(Ⅲ),and As(Ⅴ)were 12.4,5.3,and 23.0 mg/g,respectively.The adsorption behaviors were fit well with the Langmuir and the pseudo-second-order rate model.The results showed that MSSB acted as a highly effective adsorbent to simultaneously remove the composite pollution system consisted of ROX and As(Ⅲ/Ⅴ)in aqueous solutions,providing a promising method in environmental restoration applications.
文摘The adsorption characteristics of arsenate on ion exchange fiber(IEF) and iron-modified ion exchange fiber(FeIEF) were evaluated.Batch adsorption experiments were conducted to study the arsenate adsorption effect by varying contact time,pH,and coexisting anions.Adsorption capacity was found to increase by increasing the contact time and acidic conditions were favorable for arsenate adsorption on IEF and Fe-IEF.Arsenate adsorption data were better consistent with Freundlich equation than Langmuir equation.The maximum monolayer adsorption capacities were 285 and 333 mg/g at 25℃ for IEF and Fe-IEF respectively.The adsorption kinetics was found to follow the pseudo-first-order kinetic model.The existence of HCO 3-,PO34-,SO24-,SiO23-,and NO 3-decreased the arsenate adsorption capacity on IEF.Cl-and F-had little influence on it.When FeIEF was adopted,the effects of HCO 3-,SO24-,Cl-,SiO23-,and NO 3-were negligible,while PO43-could still markedly decrease the adsorption capacity and F-had inhibitory effect on arsenate adsorption.Fe-IEF can be used as a highly selective and efficient sorbent for removal of arsenate from aqueous solutions.
基金Supported by the National Natural Science Fund for Distinguished Young Scholars of China (No. 20725101)the 973 Program (No. 2006CB932904)+2 种基金the NSF of Fujian Province (No. E0510030)the Knowledge Innovation Program of CAS (No. KJCX2.YW.H01)the NNSFC (No. 20821061)
文摘One new arsenic-vanadium cluster, [Zn(dien)(Hdien)]2[As6V15O42(H2O)]·4H2O (1, dien = diethylenetriamine), has been hydrothermally synthesized and characterized by IR, elemental analysis, TGA, magnetic property and single-crystal X-ray diffraction analysis. Crystal data for 1: monoclinic, space group P21/n, a = 13.959(3), b = 22.428(5), c = 22.831(5) A^°, β = 90.733(4)°, Z = 4. X-ray crystallographic study showed that compound 1 is constructed from [As6V15O42(H2O)]^6- polyoxoanions linked together by novel [Zn(dien)(Hdien)]^3+ complex fragments via hydrogen bonds into a three-dimensional network. Variable temperature susceptibility measurement demonstrates the presence of antiferromagnetic interaction between V^IV cations in 1.
基金supported by the National Natural Science Foundation of China(No.21373043)
文摘Three new polyoxometalates K2[H2(As3O3)2(Mo6O18)(NiO6)]?H2O (1), K2[H2-(As3O3)2(Mo6O18)(CoO6)]?H2O (2) and [Zn(H4,4?-bpy)2(H2O)4][(As3O3)2(Mo6O18)(ZnO6)]?4H2O (3) (4,4?-bpy = 4,4?-bipyridine) have been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, XPS and single-crystal X-ray diffraction analyses, respectively. Compound 1 represents a new 3D framework structure constructed from polyoxoanion [(As3O3)2(Mo6O18)(NiO6)]4- via covalent bond. Compound 2 has an identical structure with 1. Compound 3 represents a new 2D layer structure constructed from transition metal coordination cations [Zn(H4,4?-bipy)2(H2O)4]4+, lattice water molecules and polyoxoanions [(As3O3)2- (Mo6O18)(ZnO6)]4- via multi-point N–H???O and O–H???O hydrogen bonding interactions. Crystal data: for 1, cubic, space group Pa-3, a = 15.0022(8) ?, V = 3376.5(3) ?3, Z = 24; for 2, cubic space group Pa-3, a = 15.1596(10), V = 3483.88 ?3, Z = 24; for 3, monoclinic, space group C2/m, a = 19.699(4), b = 14.223(3), c = 9.1455(18) ?, β = 106.80(3)o, V = 2453.0(9) ?3, Z = 8. In addition, the magnetic behaviors for compounds 1 and 2 have been investigated.
文摘Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate minerals with subordinate Cu-Pb arsenate minerals and minor Fe-Pb-Ba varieties. Based on their paragenesis these minerals may be divided into the following series: (1) the clinoclasite-olivenite-cornwallite- cornubite- debaoite- copper silicarsenate association, (2) the scorodite- carminite- beudan-tite-bayldonite- duftite association, and (3) the scorodite-Ba-bearing pharmacosiderite- dussertite association. Arsenate minerals are formed generally in the oxidized zone of the sulfide-type deposits which lie in thewarm, humid and rainy torrid-subtropical zone with pH=6-8 and contain large amounts of arsenopyrite andcarbonate rocks.
文摘In the area of recycling of spent chromated copper arsenate (CCA)-treated wood, most studies to date have focused on methods of removing/extracting the residual preservative from the wood matrix. It is well recognized that exposure of CCA-treated wood to an acid solution can reverse the CCA fixation process thereby converting the CCA elements into their water-soluble form. The economic viability of the process is enhanced because it can be integrated with other technologies and products (e.g., “green” spray foam insulation, etc.). The market for the “green” CCA is the same as for traditional CCA-the wood treating industry, principally utility poles and pilings. A market research study was conducted to determine the suitability of spent CCA-treated wood as a source for recycled, “green” CCA for manufacturing “green” spray-foam insulation. Specifically, we wanted to discern the attitudes and overall perspectives of buyers/sellers (i.e., utilities and wood treating companies) of CCA preservatives and treated wood products, disposal methods and costs for decommissioned CCA-treated wood, and understand perceptions of and willingness-to-pay for “green” CCA preservatives extracted from the technologies used in this research. Results show that 60% of wood preservative treating respondents and 60% of electric utility company respondents are somewhat or greatly interested in using out-of-service utility poles as feedstock for “green insulation” as part of a new potential business venture.
基金supported by the National Natural Sci-ence Foundation of China(No.40673079,40773076).
文摘Microbial reduction of As(V)(i.e.,arsenate)plays an important role in arsenic(As)mobilization in aqueous environment.In this study,we investigated As(V)reduction characteristics of the bacteria enriched from the arsenic-contaminated soil at an abandoned smelter site.It was found that As(V)was completely reduced to As(III)(i.e.,arsenite)in 21 h.After 3-d incubation,a yellow solid was precipitated and the concentration of As(III)decreased sharply.After 150 h incubation,ca.65%of soluble arsenic was removed fro...
基金supported by the 973 Program of China(2006CB10701-11)the National Natural Science Foundation of China(30871476)+2 种基金the Agro-Scientific Research Fundfrom the Ministry of Agriculture,China(NYHYZX07-003)the Project for High-Yielding Crop,China(2006BADOZA09)the Project for Improved Variety(2007lucainong100)
文摘A pot experiment was conducted to investigate the effect of different arsenic (As) levels on maize (Zea mays L.) growth and As accumulation and species in different parts of maize plants,as a guideline for production of maize in As-polluted areas with the objective of preventing As from entering the food chain,and improving understanding of the mechanisms of effect of As on plant.Zhengdan 958 was grown at five As levels added to soil (0,12.5,25,50,and 100 mg kg^-1 As).As concentration in maize tissues increased in the order of grain〈stalk〈leaf〈〈root.The As concentration in maize grain exceeded the maximum permissible concentration of 0.7 mg kg^-1 in China at levels of 50 and 100 mg kg^-1.As species were presented in root,stalk,and grain,but organic As was the major As species identified in the grain.Maize plants were able to reduce arsenate to arsenite.Low As levels of 12.5 and 25 mg kg^-1 improved maize growth and grain nutrition quality,while high levels of As 50 or 100 mg kg^-1 inhibited them.Yield reduction at high As levels resulted mainly from reduced ear length,kernel number per row,and kernel weight.
基金The Natural Science Foundation of China (No. 40225002) the Ministry of Science and Technology of China (No. 2002CB410808) and the Chinese Academy of Sciences (Hundred Talent Program)
文摘In the present study, arsenate(As(V)) and phosphate(P(V)) interactions were investigated in growth, uptake and RNA content in yeast(Saccharomyces cerevisiae). Yeast grew slowly with As(V) concentrations increasing in the medium. However, the maximal population density was almost the same among different As(V) treatments. It was in the late log phase that yeast growth was aug- mented by low As(V), which was maybe due to the fact that methionine metabolism was stressed by vitamin B6 deprivation, so As(V) treatments did not affect maximal population density. However, with P (V) concentrations increasing, the maximal population density increased. Therefore, the maximal population density was determined by P (V) concentrations in the medium but not by As (V) concentrations in the medium. Ycflp(a tonoplast transpor) transports As(GS)3 into the vacuole, but arsenic(As) remaining in the thalli was 1.27% with As(V) exposure for 60 h, from which it can be speculated that the percentage of As transported into vacuole should be lower than 1.27%. However, the percentage of As pumped out of cell was 71.49% with As (V) exposure for 68 h. Although two pathways (extrusion and sequestration) were involved in As detoxification in yeast, the extrusion pathway played a major role in As detoxification. RNA content was the highest in the early-log phase and was reduced by As(V).
文摘The influence of arsenate and phosphate on the growth and respiration of 21 days old seedlings in two cultivars of rice, viz., IR64 and Nayanmani was studied. As arsenate and phosphate are similar in their chemical configuration and the latter is preferentially taken up by the phosphate transporters, it results in a competitive inhibition of arsenate uptake in presence of phosphate. Increasing concentrations of sodium arsenate (25 μM, 50 μM and 100 μM) hindered the growth in both the cultivars, with cv. IR64 being more severely affected than cv. Nayanmani. There was an elevation in the levels of organic acids measured in both the cultivars, accompanied by a reduction in the activities of the dehydrogenases of the TCA cycle, viz., pyruvate dehydrogenase, isocitrate dehydrogenase, succinate dehydrogenase and malate dedrogenase under arsenic treatment alone. Also, an elevation in the activities of citrate synthase and fumarase enzymes was noticed in both test seedlings with increasing concentrations of arsenic. These alterations were more prominent in cv. IR64 than in cv. Nayanmani. On joint application of phosphate along with arsenate, amelioration of the toxic effects of arsenate was observed to some extent, resulting in an overall revival of respiration leading to improved growth and metabolism.
文摘A pot experiment was conducted to investigate the heavy metal accumulation in maize (Zea mays L.) plant grown in chromated copper arsenate (CCA) soil amended with treated composted sewage biosolid. The initial concentrations of chromium, copper, arsenate in the CCA soil and sewage biosolid were determined by atomic absorption spectrophotometer. These were found to be, in CCA soil: 365.8 ± 6.18, 109.22 ± 14.04, 28.22 ± 3.8 and in sewage biosolid: 35 ± 1.06, 1.0 ± 0.02, 0 mg·kg-1 respectively. The concentration of Cr, Cu and As determined in both the roots and shoots generally decreased with increase in percentage amendment concentration and number of days (20 and 40 days after planting). At 20 days, the total metal concentration ranges in roots were As (5.54 ± 0.03 - 6.69 ± 1.14), Cr (9.59 ± 0.02 - 13.22 ± 0.03), Cu (2.28 ± 0.06 - 4.53 ± 0.37) mg·kg-1 while at 40 days the values were As (5.60 ± 0.19 - 6.08 ± 0.01), Cr (9.47 ± 0.04 - 10.95 ± 0.09), Cu (3.94 ± 0.19 - 4.64 ± 0.07) mg·kg-1. For the shoot system, the concentrations of the metals at 20 days were As (5.28 ± 0.03 - 5.90 ± 0.13), Cr (9.30 ± 0.05 - 10.07 ± 0.06), Cu (3.64 ± 0.12 - 4.72 ± 0.15) mg/kg while at 40 days the values obtained were As (5.28 ± 0.03 - 5.9 ± 0.13), Cr (9.69 ± 0.14 - 10.07 ± 0.03), Cu (2.94 ± 0.72 - 4.53 ± 0.03) mg·kg-1. The roots accumulated the three heavy metals more than the shoot system at all treatments used. Concentration of arsenic, chromium and copper in the plants decreased with increasing percentage amendments. The results suggest relatively low bioavailability of the three metals in CCA soil treated with high percentages of sewage biosolid as an amendment.
基金supported by the National Natural Science Foundation of China (Nos.41991332,41977323 and 42090063)the National Institutes of Health (No.R35 GM136211)。
文摘Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well documented,while little is known regarding effects due to endophytic bacteria.An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil.P.putida ARS1 shows high tolerance to arsenite(As(Ⅲ))and arsenate(As(V)),and exhibits efficient As(V)reduction and As(Ⅲ)effux activities.When exposed to 0.6 mg/L As(V),As(V)in the medium was completely converted to As(Ⅲ)by P.putida ARS1 within 4 hr.Genome sequencing showed that P.putida ARS1 has two chromosomal arsenic resistance gene clusters(arsRCBH)that contribute to efficient As(V)reduction and As(Ⅲ)effux,and result in high resistance to arsenicals.Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation,which takes up As(Ⅲ)more efficiently than As(V).Co-culture of P.putida ARS1 and W.globosa enhanced arsenic accumulation in W.globosa by 69%,and resulted in 91%removal of arsenic(at initial concentration of 0.6 mg/L As(V))from water within 3 days.This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium.
基金supported by the General Programs (No. 41472219)the Foundations for Innovative Research Groups (No. 41521001) from the National Natural Science Foundation of China。
文摘Many investigations suggest that dissimilatory arsenate-respiring prokaryotes (DARPs) play a key role in stimulating reductive mobilization of As from solid phase into groundwater,but it is not clear how environmental Mn(Ⅱ) affects the DARPs-mediated reductive mobilization of arsenic.To resolve this issue,we collected soil samples from a realgar tailingsaffected area.We found that there were diverse arsenate-respiratory reductase (arr) genes in the soils.The microbial communities had high arsenate-respiring activity,and were able to efficiently stimulate the reductive mobilization of As.Compared to the microcosms without Mn(Ⅱ),addition of 10 mmol/L Mn(Ⅱ) to the microcosms led to 23.99%-251.79% increases in the microbial mobilization of As,and led to 133.3%-239.2% increases in the abundances of arr genes.We further isolated a new cultivable DARP,Bacillus sp.F11,from the arseniccontaminated soils.It completely reduced 1 mmol/L As(V) in 5 days under the optimal reaction conditions.We further found that it was able to efficiently catalyze the reductive mobilization and release of As from the solid phase;the addition of 2 mmol/L Mn(Ⅱ) led to 98.49%-248.78% increases in the F11 cells-mediated reductive mobilization of As,and70.6%-104.4% increases in the arr gene abundances.These data suggest that environmental Mn(Ⅱ) markedly increased the DARPs-mediated reductive mobilization of As in arseniccontaminated soils.This work provided a new insight into the close association between the biogeochemical cycles of arsenic and manganese.
基金supported by the National Nature Science Foundation of China (Nos. 42177384 and 41976150)the Nature Science Foundation of Fujian Province (No. 2020J01804)the Program for New Century Excellent Talents in Fujian Province University。
文摘Little information is available on influences of the conversion of dissolved organic phosphorus(DOP) to inorganic phosphorus(IP) on algal growth and subsequent behaviors of arsenate(As(V)) in Microcystis aeruginosa(M. aeruginosa). In this study, the influences factors on the conversion of three typical DOP types including adenosine-5-triphosphate disodium salt(ATP), β-glycerophosphate sodium(βP) and D-glucose-6-phosphate disodium salt(GP)were investigated under different extracellular polymeric secretions(EPS) ratios from M.aeruginosa, and As(V) levels. Thus, algal growth, As(V) biotransformation and microcystins(MCs) release of M. aeruginosa were explored in the different converted DOP conditions compared with IP. Results showed that the three DOP to IP without EPS addition became in favor of algal growth during their conversion. Compared with IP, M. aeruginosa growth was thus facilitated in the three converted DOP conditions, subsequently resulting in potential algal bloom particularly at arsenic(As) contaminated water environment. Additionally, DOP after conversion could inhibit As accumulation in M. aeruginosa, thus intracellular As accumulation was lower in the converted DOP conditions than that in IP condition. As(V) biotransformation and MCs release in M. aeruginosa was impacted by different converted DOP with their different types. Specifically, DMA concentrations in media and As(III) ratios in algal cells were promoted in converted βP condition, indicating that the observed dissolved organic compositions from βP conversion could enhance As(V) reduction in M. aeruginosa and then accelerate DMA release. The obtained findings can provide better understanding of cyanobacteria blooms and As biotransformation in different DOP as the main phosphorus source.
基金supported by the National Natural Sci- ence Foundation of China (No. 40973058, 21077100)the Doctor Foundation of Shandong Province (No. BS2009HZ024)
文摘Arsenic (As) is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide. Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in freshwater aquatic systems. Arsenic metabolism processes of this alga through arsenate reduction and sequent store and efflux were investigated. When supplied with 10 μmol/L arsenate, arsenic speciation analysis showed that arsenite concentration increased from 5.7 to 15.7 mg/kg dry weight during a 7-day period, accounting for 18%–24% of the total As in alga. When treated with different levels of arsenate (10, 20, 30, 40, 50 μmol/L) for 7 days, the arsenite concentration increased with increasing external arsenate concentrations, the proportion of arsenite was up to 23%–28% of the total As in alga. In efflux experiments, both arsenate and arsenite could be found in the efflux solutions. Additionally, the efflux of arsenate was more than that of arsenite. Furthermore, two arsenate reductase genes of C. reinhardtii (CrACR2s) were cloned and expressed in Escherichia coli strain WC3110 (?arsC) for the first time. The abilities of both CrACR2s genes to complement the arsenate- sensitive strain were examined. CrACR2.1 restored arsenate resistance at 0.8 mmol/L. However, CrACR2.2 showed much less ability to complement. The gene products were demonstrated to reduce arsenate to arsenite in vivo. In agreement with the complementation results, CrACR2.1 showed higher reduction ability than CrACR2.2, when treated with 0.4 mmol/L arsenate for 16 hr incubation.