Effect of Zn(II) on the reduction and accumulation of Cr(VI) by <Emphasis Type="Italic">Arthrobacter</Emphasis> species

Natural habitats are often characterized by the coexistence of Zn and Cr. This study assessed the potential of two Gram-positive, Cr(VI)-reducing, aerobic bacterial strains belonging to Arthrobacter genera, which were isolated from basalt samples taken from the most polluted region of the Republic of Georgia, to remediate Cr(VI) in environments in the presence of Zn(II). Our batch experiments revealed that the addition of Zn(II) to the tested bacterial cells significantly enhanced the accumulation of Cr. According to electron spin resonance (ESR) measurements, the presence of Zn(II) ions did not change the nature of Cr(V) and Cr(III) complexes generated during the microbial reduction of Cr(VI). The efficiency of Cr(VI) reduction also remained unchanged after the addition of 50 mg/l of Zn(II) to the bacterial cells. However, at high concentrations of Zn(II) (higher than 200 mg/l), the transformation of Cr(VI) to Cr(V) and Cr(III) complexes decreases significantly. In addition, it was shown that the accumulation pattern of Zn in the tested bacterial species in the presence of 100 mg/l of Cr(VI) fits the Langmuir–Freundlich model well. The two tested bacterial strains exhibited different characteristics of Zn accumulation.     

Biosorption of chromium, copper, manganese and zinc by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum

The study describes the sorption of Cr, Cu, Mn and Zn by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum and heavy metals. The concentrations studied were 50, 49, 60 and 70 (mg L(-1)) for Cr, Cu, Mn and Zn, respectively. The solution pH and ionic strength were very important factors in the metal biosorption performance and the biosorption capacity of P. aeruginosa AT18 for Cr3+,Cu2+, Mn2+ and Zn2+. In aqueous solution, the biosorption increased with increasing pH in the range 5.46-7.72. The results obtained in the experimental assays show that P. aeruginosa AT18 has the capacity for biosorption of the metallic ions Cr3+, Cu2+ and Zn2+ in solutions, although its capacity for the sorption of manganese is low (22.39 mg Mn2+/g of biomass) in comparison to the Cr3+, Cu2+ and Zn2+ ions, as shown by the individual analyses. However, 20% of the manganese was removed from an initial concentration of 49.0 mg L(-1), with a Qm value similar to that obtained in solutions containing mixtures of Cr3+, Cu2+, Mn2+and Zn2+. The chromium level sorbed by P. aeruginosa AT18 biomass was higher than that for Cu, Mn and Zn, with 100% removal in the pH range 7.00-7.72 and a Qm of 121.90-200.00 mg of Cr3+/g of biomass. The removal of Cr, Cu and Zn is also a result of precipitation processes.     

Mineral and chemical characteristics,textural parameters,and the mobility of the selected elements of flotation waste,originating from the Polish copper-mining industry

This article discusses the mineralogy and geochemical characteristics of the fresh copper-flotation waste samples. The mobility of As, Cd, Cr, Cu, Ni, Pb, Tl, Zn was investigated by leaching tests. The main mineral phases identified concerned dolomite, quartz, clay minerals, feldspars, and copper-bearing minerals. Chemically, CaO and silica were dominating, along with a significant concentration of precious (Cu), refractory (Cr, Ti, V, Zr), and toxic (As, Cd, Pb) metals. Elements were bound mainly to the residual fraction and sulphides in the following order: Pb > Cu ≈ Tl > As ≈ Zn > Ni ≈ Cr > Cd. The metal mobility patterns expressed as a percentage of total concentrations, were as follows: Cd (42%) > Cr (26%)> Ni (24%) > Zn (23%) > As (22%) > Tl (20%) > Cu (18%) > Pb (2%). Those constituents were released earlier in lower pH values, although Cu, Cr, and Pb were also released in higher alkaline pH values. However, Zn release was not dependent on pH. When L/S values decreased, elements like As, Cr, Cu, Pb, and Tl were released. That process caused decrease of Cd, Ni, and Zn release.     

广西英罗湾红海榄林重金属元素的累积及动态

 探讨了广西英罗湾红海榄红树林重金属Cu、Pb、Zn、Cd、Cr元素的累积及动态。结果表明：植物体不同部位元素的含量范围,分别为Cu 0.433～1.21、Pb 0.369～1.88、Zn 2.94～7.66、Cd0.020～0.233和Cr0.330～0.562μg／g。林地残留物组分元素含量远高于植物体及凋落物组分含量。该群落Cu、Pb、Zn、Cd、Cr的现存储量,分别为28.73、25.25、143.68、3.14和14.61mg／m2。林地残留物相应元素的储量,分别为271.68、323.41、1983.70、8.18和34.44μg／m2。群落Cu、Pb、Zn、Cd、Cr元素的生物循环为：年吸收量分别为1351.70、1613.12、8808.37、240.74和759.30μg／m2;年存留量分别为842.46、806.91、4694.10,94.88和464.80μg／m2;年归还量分别为509.24、806.21、4114.27、145.86和294.50μg／m2;周转期分别为56、31、35、22和50年;流动系数Cd>Pb、Zn>Cu、Cr。     

Comparison of the toxicity of heavy metals to cabbage growth

Summary Cabbage plants were grown for 55 days with a nutrient solution containing 1 and 10 ppm of V, Cr(III), Cr(VI), Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg(I), orHg(II). A comparison of the plant growth and chemical analysis revealed that Cr(VI), Cu, Cd, and Hg(II) in the solution are most toxic to the plant growth (hence detrimental to the cabbage-head formation) and Mn, Fe, and Zn are less toxic than other heavy metals, and that Mn, Zn, Co, Ni, and Cd and translocated into all the plant organs while V, Cr(III), Cr(VI), Fe, Cu, Hg(I), and Hg(II) are accumulated in the roots.     

Differential effects of Zn concentrations on Cr(VI) uptake by two Salvinia species: involvement of thiol compounds

Abstract

Floating ferns of the genus Salvinia have great potential for phytoremediation of heavy metals. To date, the effect of essential metals on the accumulation and transport of toxic metals by aquatic ferns has not been suitably established. The aim of this study was to compare the ability of floating leaves of Salvinia minima and Salvinia rotundifolia species to accumulate Cr from Cr(VI solutions containing very low (0.02?mg L^?1) and low (5?mg L^?1) Zn concentrations. After 7-day metal-exposure period, results showed that Zn increased Cr accumulation in S. minima leaves whereas in S. rotundifolia decreased significantly. Contrarily Zn accumulation did not show great differences between species. This fact may indicate that Zn interfere Cr(VI) uptake by S. rotundifolia. Bioconcentration factor (BCF) and translocation factor (TF) were affected differently by Zn in both Salvinia species. Membrane stability index (MSI) of both Salvinia species was decreased significantly by 5?mg L^?1 Zn concentration. Zn ions also increased hydrogen peroxide accumulation in fronds of Salvinia species. Total thiols (TT), non-protein thiols (NPT) and protein-bound thiols (PBT) were differentially affected by Cr(VI) and Zn ions. This study provides evidences on the involvement of different mechanisms against Cr(VI)/Zn toxicity in S. minima and S rotundifolia species.     

Effects of nitrilotriacetic acid on the induction of gene mutations and sister-chromatid exchanges by insoluble chromium compounds

The influence of nitrilotriacetic acid trisodium salt (NTA) on the mutagenic and clastogenic activity of several water-insoluble or poorly soluble chromium compounds was determined by means of the Salmonella/microsome assay (plate test on TA100 strain) and the sister-chromatid exchange (SCE) test in mammalian cell cultures (CHO line). NTA in itself did not induce gene mutations nor did it increase the frequency of SCE. Cr(VI) compounds (Pb, Ba, Zn, Sr and Ca chromates) and an industrial Cr(VI) pigment, chromium orange (containing PbCrO4 PbO), were inactive or scarcely active mutagens in the Salmonella/microsome test when dissolved in water, but they were increasingly mutagenic when solubilized by 0.5 N NaOH or NTA (10 or 100 mg/ml). Also, the mutagenic activity of Cr(VI), contaminating an industrial Cr(III) pigment (chromite), was slightly enhanced by NTA. Mutagenicity of chromates was correlated with the amounts of Cr(VI) solubilized by NTA or alkali, as determined by the colorimetric reaction with diphenylcarbazide and atomic absorption spectrophotometry, and was decreased by incubation with microsomes, due to reduction of Cr(VI) to the genetically inactive Cr(III) form. In the SCE assay, the insoluble or poorly soluble Ba, Zn, Sr and Ca chromates and the insoluble Cr(VI) pigments zinc yellow (containing ZnCrO4 Zn(OH2], chromium yellow and molybdenum orange (both containing PbCrO4) were directly clastogenic due to cellular endocytosis taking place in prolonged treatments, and NTA significantly increased their chromosome-damaging activity.     

Trace elements in hair of healthy children sampled by age and sex

Hair trace element (TE) (Cr, Mn, Fe, Zn, Cu, Br, Rb, Sr, Pb) levels from 336 healthy subjects were measured by the Proton-Induced X-ray Emission (PIXE) method. The subjects were divided in three groups: 157 full-term neonates (75 male and 82 female), 86 children (41 male and 45 female) ages 6 to 11 yr, and 93 adolescents (51 male and 42 female) 11 to 16 yr old. Cu, Zn, Cr, and Br show an increase from birth to 8 yr and then decrease. Fe, Mn, and Sr strongly decrease up to 8 yr and then remain almost stable. Sex differences are present in Fe, Zn, and Br of children and in Cu, Cr, and Br of adolescents.     

Effect of chromium and zinc on insulin signaling in skeletal muscle cells

Patients on total parenteral nutrition without Cr supplementation develop symptoms similar to those of diabetes. Zn has been implicated in diabetes because of its antioxidant properties and interaction with insulin. To study the effect of these metal ions on insulin signaling proteins, cultured mouse skeletal muscle cells was used as an in vitro model, as the tissue accounts for more than 80% of insulin-stimulated glucose disposal in the body. In the present study, it has been observed that both Cr and Zn, upon prolonged exposure, could stimulate tyrosine phosphorylation of insulin receptor (IR) even in the absence of insulin. Insulin-mediated IR tyrosine phosphorylation was enhanced by the treatment with both of the metal ions. Both Cr and Zn could phosphorylate insulin receptor substrate-1 (IRS-1). Phosphorylation of IRS-1 induced by metal ions was higher than that induced by insulin. Hence, both Cr and Zn were found to have insulin mimetic activity. Both of the metal ions were also found to potentiate insulin-mediated activation of IRS-1. The basal level of glucose uptake was also increased by prolonged treatment of the cells with the metal ions. The ions could also enhance the insulin-stimulated glucose uptake into the cells. Therefore, both Zn and Cr seem to have a positive effect on insulin signaling leading to glucose uptake.     

刺楸年轮中重金属含量动态变化及富集特性

为探索刺楸对受污染土壤重金属的富集和修复效应, 以南京栖霞山的乡土树种刺楸及其根际周边土壤为研究对象, 截取其根基部年轮盘及根际土壤样本, 采用ICP-AES法测定年轮及土壤样本中重金属(Cu、Cd、Cr、Mn、Ni、Pb、Zn)元素含量。结果表明: 栖霞山样地中的土壤受Mn、Pb和Zn污染最为严重, 存在Cu、Cd、Mn、Pb、Zn元素的高度复合污染, Cd、Cr、Cu、Ni、Zn在土壤和年轮中存在相关性, Mn和Pb则没有表现出明显的相关性; 刺楸修复受Cd、Mn、Pb、Zn污染的土壤效果并不显著, 更适用于Cr、Cu、Ni污染的土壤修复; 鉴于Cu元素含量变化特征, 刺楸也可以作为反映当地污染历史的记录载体; 刺楸年轮中的重金属元素之间存在交互作用, 其中Cd与Zn元素含量高度相关(r=0.984, p<0.01), 在刺楸年轮吸收重金属元素的过程中, Cu与Cd、Cr、Mn、Zn元素具有协同作用, Mn元素对其他元素有一定的拮抗作用。     

Bioaccumulation of heavy metals in Dactylis glomerata L. growing in a calcareous soil amended with sewage sludge

The total and DTPA-extractable concentrations of Pb, Ni, Zn, Cu, Cr and Cd were measured in a calcareous soil amended with different doses of sewage sludge under field conditions. The same metals were also measured in the roots and leaves of Dactylis glomerata at the end of the first vegetative period after the sludge was added. The root concentrations of all the metals were unrelated to their concentrations in the soil. Leaf concentrations of Zn and Cr correlated with total (Zn) and DTPA-extractable (Zn and Cr) concentrations in the soil. DTPA extraction did not appear to be very useful for evaluating the bioavailability of metals in this kind of soil as it gave very low correlation coefficients with leaf content (r = 0.684, P = 0.0049 for Zn and r = 0.557, P = 0.0249 for Cr). Concentrations of Pb, Ni, Cu, and Cd in roots and leaves of Dactylis glomerata were unrelated to the total or DTPA-extractable concentrations in the sludge-amended soil.     

Impact of exogenous silicon addition on chromium uptake, growth, mineral elements, oxidative stress, antioxidant capacity, and leaf and root structures in rice seedlings exposed to hexavalent chromium

Hydroponic experiments were conducted to investigate the role of exogenous silicon (Si) addition in increasing hexavalent chromium (Cr VI) tolerance in rice seedlings. Rice seedlings were grown under 100 μM Cr(VI) stress without or with 10 μM Si. Chromium treatment decreased growth, photosynthetic pigments and protein, which was accompanied by a significant increase in Cr accumulation and lipid peroxidation (as malondialdehyde; MDA). However, Si addition alleviated Cr toxicity and promoted growth of rice by decreasing Cr accumulation, root-to-shoot Cr transport and MDA level. Contents of macro (Mg, Ca and K) as well as micronutrients (Zn and Fe) were decreased by Cr except Mn while Si addition prevented decrease in these nutrients induced by Cr. Antioxidant capacity and total phenolic contents were decreased by Cr while these indices improved by Si addition. Treatment of Cr decreased the length of leaf epidermal cells and stomatal frequency, and adversely affected chloroplasts containing mesophyll cells and integrity of xylem and phloem, and Si addition minimized these abnormalities. However, frequency of root hairs was increased by Cr treatment. Results showed that exogenous Si addition enhanced Cr(VI) tolerance in rice seedlings by decreasing Cr accumulation, root-to-shoot Cr transport and MDA level, and by increasing content of some mineral elements (K, Fe and Zn) and antioxidant capacity compared to the Cr treatment alone.     

Mineral content in the wild onion species and their nutritive value

The accumulation of 11 microelements (Fe, Zn, Cu, Co, Mn, Ni, Pb, Cd, Sr, Cr, and Se) by 7 wild onion species of the genus Allium was studied. A. flavescens Bess possesses the higher accumulating capability; it accumulates five of eleven microelements (Cr, Ni, Cu, Zn, and Se) with biological accumulation coefficient (BAC) exceeding 1 and also contains high levels of Fe, Co, and Mn. These features enable this species to be the most promising for the nutrition adjustment of human commons with above-mentioned microelements primarily with Cr, which content in 100 g onion leaves achieves 84% of commons. A. fistulosum L., A. odorum L., and broad-leaved A. nutans form specifically accumulate Cu, Zn, and Se. A. montanum Schmidt is characterized by the accumulation of Zn. A. angulosum and A. schoenoprasum are xharacterized by the accumulation of Se. The broad-leaved forms of A. schoenoprasum L., A. nutans L., and A. odorum L. compared with their narrow-leaved forms accumulate more amounts of Zn and Cu.     

Heavy metals in water,sediments, fish and plants of river Hindon,U.P., India

We analysed the concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the water, sediments, fish and plants of the River Hindon, U.P., India, at seven sampling stations, in the year 1982. Considerable variation in concentration between water, sediments, fish and plants were noted. The concentration in the water was in the order Fe > Zn > Cr > Mn > Cu > Pb > Ni > Co > Cd, in the sediments, Fe > Mn > Zn > Ni > Cr > - Co > Cu > Pb > Cd; in a fish (Heteropnuestes fossilis) Fe > Zn > Mn > Pb > Ni > Co > Cu > Cd > Cr, and in a plant (Eicchornia crassipes) Fe > Mn > Zn > Ni > Cu > Cr > Pb > Co > Cd.     

Hexavalent chromium uptake and its effects on mineral uptake, antioxidant defence system and photosynthesis in Amaranthus viridis L

The effects of different concentrations (10(-6)M, 10(-5)M and 10(-4)M) of K2Cr2O7Cr(VI) on some minerals (Mn, Fe, Cu and Zn), lipid peroxidation, activities of antioxidant enzymes, photosynthetic function, and chlorophyll fluorescence characteristics were investigated in hydroponically grown Amaranthus viridis L. Results indicated that chromium was accumulated primarily in roots. In the roots and shoots, the Cr content increased with the increasing Cr(VI) concentrations, and induced decrease of Mn, Fe, Cu and Zn. Chromium Cr(VI) induced oxidation stress and lipid peroxidation in A. viridis L. shown by the increased concentration of MDA. The increased activities of POD and SOD indicated that they could serve as important components of antioxidant defense mechanisms to minimize Cr induced oxidative injury. The net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 concentration were reduced only by high Cr(VI) treatments (10(-5)M and 10(-4)M). The chlorophyll fluorescence parameters Fv/Fm, Fv(')/Fm('), Phi PSII and qP, decreased in Cr(VI)-treated, but qN and NPQ showed an increase in Cr(VI) treated plants.     

浙江油茶产地土壤和果实金属元素含量特征

为探讨油茶(Camellia oleifera)产地土壤和油茶果实中金属元素分布和富集特征,在油茶果实成熟期,对浙江5个油茶产地土壤及油茶果实中金属元素进行污染分析和富集能力评价.结果表明,浙江油茶产地土壤中Pb、Cr、Cd、As、Hg、Ni、Cu和Zn含量低于农用地土壤污染风险筛选值,综合污染等级为安全.个别产区常山...     

Seasonal and locational effects on serum, milk, liver and kidney chromium, manganese, copper, zinc, and iron concentrations of dairy cows

Chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe) concentrations were quantified in serum (n=112), milk (n=112), liver (n=70), and kidney samples (n=67) of dairy cows from an iron-steel processing region (Payas-Iskenderun) and from an area free of industrial pollution (Antakya) in Hatay, located in Southern Turkey. Samples were collected in the summer and winter and element determinations were carried out by inductively coupled plasma-atomic emission spectrometry. The mean concentrations of selected elements in serum were found to be similar in both regions. Milk samples collected from the nonindustrial region in the summer had higher Cr, Mn, and Zn concentrations than the polluted region. The liver Cu and kidney Mn levels of samples taken from the industrial region in winter were higher than samples of the unpolluted region. Copper and Fe concentrations in milk, Cr, Mn, Zn, and Fe levels in the liver, and Cr, Cu, Zn, and Fe levels in kidney samples were not found to be different among the regions in both seasons. Copper concentrations were below the critical level in the 25% of serum and 32% of liver samples analyzed in this study. Fifteen percent of serum samples and most of the liver samples had lower amounts of Zn than other reported studies. Although slight differences were observed between the industrial and nonindustrial regions, industrial activities and seasonal changes had no significant effect on selected element concentrations on cows and their milk.     

Accumulation and toxic effects of chromium and zinc in Iris pseudacorus L.

The aim of the present study was to examine the ability of I. pseudacorus L., an ornamental macrophyte of great potential for phytoremediation, to tolerate and accumulate Cr and Zn. Plants were grown in nutritive solution with ZnCl₂ or CrCl₃·6H₂O at 0, 10, 50, 100, and 200 μg ml⁻¹ for 5 weeks; all survived and continued growing. The accumulation of Cr and Zn increased with increasing supply in all plant tissues, to reach 59.97 mg Cr and 25.64 mg Zn in roots. Leaves retained a remarkable amount of Zn (14.2 mg). Growth inhibition reached 65% and 31% (dry weight) in response to Cr and Zn, respectively. The root:shoot dry matter partitioning (R/S) increased 80% at 100 μg ml⁻¹ CrCl₃. The most marked alterations in mineral content were in roots, where both metals decreased Al, Ca, Mg, Mn and S, and increased P concentration. No effect was noted on either leaf chlorophyll fluorescence kinetics (F _v /F _m and Φ_PSII), or photosynthetic pigment content, signifying that the light phase of photosynthesis was not impaired. Carbon isotope composition (δ¹³C) was only slightly heavier, indicating that the reduction of carbon fixation was not the main cause for growth decrease. This was attributed to the restricted mineral uptake and to the increased demand of carbohydrates of damaged roots. Biomass allocation to rhizomes (Cr) or roots (Zn) contributes to heavy metal tolerance by limiting transpiration and increasing metal–storing tissues and the surface for water and cation uptake. This species is a good candidate for Cr rhizofiltration and Zn phytoextraction.     

Antioxidant properties of chromium and zinc

The effects of chromium (chromium picolinate, CrPic) and zinc (ZnSO₄H₂O) supplementation on serum concentrations of malondialdehyde (MDA) (an indicator of lipid peroxidation) and serum status of some antioxidant vitamins and minerals of laying hens (Hy-Line) reared at a low ambient temperature (6.8°C) were evaluated. One hundred twenty laying hens (Hy-Line; 32 wk old) were divided into 4 groups, 30 hens per group. The hens were fed either a basal diet or the basal diet supplemented with either 0.4 mg Cr/kg of diet, 30 mg Zn/kg of diet, or 0.4 mg Cr plus 30 mg Zn/kg of diet. Digestibility of nutrients (dry matter [DM], organic matter [OM], crude protein [CP], and ether extract [EE]) increased by supplementation of chromium and zinc (p<0.05). Supplemental chromium and zinc increased serum vitamins C and E but decreased MDA concentrations (p<0.05). Additionally, supplemental chromium and zinc caused an increase in the serum concentrations of Fe, Zn, Mn, and Cr (p < 0.05). The present study showed that low ambient temperature causes detrimental effects on the digestibility of nutrients and antioxidant status and that such detrimental effects caused by low ambient temperature can be alleviated by chromium and zinc supplementation, particularly when Cr and Zn were simultaneously included into the diet. Data obtained in the present study suggest that such supplementation can be considered as a protective management practice in a diet of laying hens for alleviating negative effects of cold stress.     

贵州水银洞金矿紫茎泽兰重金属元素测定与分析

利用原子吸收法对贵州水银洞金矿紫茎泽兰及其基质中Cr、Pb、Zn、Cd、Hg和As含量进行了测定和分析。结果表明,贵州水银洞金矿废水处理区土壤Hg(12.575 mg·kg^-1)和As(501.374 mg·kg^-1)已严重超标,Hg和As的平均含量分别是国家土壤环境质量三级标准(GB15618-1995)的8.383倍和12.534倍,污染极为严重;紫茎泽兰对该矿区不同的重金属富集能力不同,尤其对该矿区Cr有较强的富集作用,具有一定的Cr污染修复潜力。紫茎泽兰对所测定的6种重金属元素的吸收转移能力有较大的差异,整个植株对Pb、Zn 和Cr具有很强的吸收转移能力。其茎、叶对不同的重金属元素的吸收转移能力也呈现出很大的差异,紫茎泽兰茎对Cr、Pb和Cd具有很强的吸收转移能力,而叶对Zn、Pb和Hg具有很强的吸收转移能力。除As外,紫茎泽兰对Cr、Pb、Zn、Cd和Hg都具有不同程度的耐受能力,对该矿区的生态恢复具有重要的作用。