Metal Concentration In Solution Research Articles

Studies on bioremediation of Zn and acid waters using Botryococcus braunii

In the present article the effects of Zn(II) on Botryococcus braunii in terms of growth and the photosynthesis-respiration metabolism and the ability of this microalgae to remove zinc present in wastewaters is described. The photosynthetic and respiration rates are affected by increasing metal concentration in solution, and therefore B. braunii growth rate decreases to a half, nevertheless the maximum value of biomass reached (770 ± 40 mg l−1) is the same and the biomass remains viable throughout the range of concentrations studied (0–80 mg l−1). B. braunii exposed the ability to reverse the acidic conditions of the medium, showing a pH increase from 5.2 till values above 8.0 favoring the precipitation of different zinc compounds. Zn(II) specific removal increases along with initial metal concentration. The net adsorption capacity was determined, and the Freundlich, Langmuir and Hill models were applied. The stoichiometric relationship between H+ release and zinc uptake in slightly acidic conditions is 1:1, and the adsorption kinetics follows a pseudo-second order model. The amount of metal removed increase when metabolic processes are involved. Removal of Zn with successive additions was achieved along 200 days, reaching a value of zinc removal of 3.4 g g−1. The remediation of heavy metals (zinc, nickel and copper) and nitrates present in a leachate obtained from a bioleaching process was successfully performed. The present work represents a new approach on the biotechnological potential of B. braunii to grow in acidic conditions and to remove zinc, while differentiates passive adsorption from metabolically active remediation.

Optimization of Cu (II) biosorption onto sea urchin test using response surface methodology and artificial neural networks

Copper biosorption potential of the biomass prepared from shells of sea urchin from aqueous solutions at optimum process conditions was studied. Response surface methodology and artificial neural network combined with central composite design were used for modeling and optimization of biosorption and to study interaction effects of process variables. A two-level three-factor face-centered central composite design was used for the experimental design. The influence of pH, initial copper concentration and biosorbent dosage on biosorption of copper was investigated. Prediction capacities of both models were compared and found that response surface methodology showed better prediction performance than artificial neural networks. Kinetic data were well fitted to second-order rate equation showing maximum biosorption capacity of 15.625 mg/g for 100 mg/l metal solution concentration. It was further confirmed by fitting the data to Elovich model. Biosorption mechanism was investigated using intra-particle diffusion and Boyd models. The optimum copper removal efficiency of the biosorbent was found as 89.09%.

Acute toxicity of some heavy metals to the fresh water snail, Theodoxus niloticus (Reeve, 1856)

Three toxicity experiments were carried out separately to study the toxicity effects of Zn, Fe and Pb on adult freshwater snail Theodoxus niloticus (Gastropod, Prosobranchia, Nertidae). The LC50 values for the 96 hr exposures of Zn, Fe and Pb on Theodoxus niloticus were 12.199, 8.6 and 18 mg/l respectively. These values increased by decreasing the time of exposure. Fe was more toxic followed by Zn and Pb to Theodoxus niloticus. The rate of mortality increased by increasing the exposure period and concentration of metals in solution. Moreover, bioconcentration of Zn, Fe and Pb in soft parts and shell increased gradually by increasing the concentrations of each metal in solutions. After 96 hr of exposure, the bioaccumulation factors for each metal were decreased from highest values in the control to the lowest one with the highest concentration of the metal. It is difficult to compare LC50 values for metals for this species with those for other gastropod species due to different abilities of closely related taxa or the species belonging to the same genus, which live in the same habitats, to accumulate metals.

Biosynthesis of silver nanocomposite with Tarragon leaf extract and assessment of antibacterial activity

The aqueous extract of Tarragon, as a reducing agent, was used to synthesize silver–montmorillonite (MMT) nanocomposite (Ag–MMT-NPs) in the batch method. The leaf extract and metal solution concentrations were optimized to improve Ag–MMT-NPs synthesis in 48 h. For characterizing the nanocomposite, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and UV–Vis spectroscopy were performed. The peak was observed at 437 nm on the UV–Vis spectrum, showing the surface plasmon resonance of Ag–MMT-NPs. Using XRD analysis, the crystalline nature and purity of Ag–MMT-NPs were confirmed. FTIR was used to evaluate specific functional groups, causing a reduction in silver nitrate during Ag–MMT-NPs formation. According to TEM, the average particle size was 25.12 nm in AgNPs. The nanocomposite showed antibacterial properties against Gram-negative and Gram-positive bacteria (Escherichia coli and Staphylococcus aureus).Graphical

Controls on accumulation and soil solution partitioning of heavy metals across upland sites in United Kingdom (UK)

A significant body of knowledge suggests that soil solution pH and dissolved organic carbon (DOC) strongly influence metal concentrations and speciation in porewater, however, these effects vary between different metals. This study investigated the factors influencing soil and soil solution concentrations of copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) under field conditions in upland soils from UK having a wide range of pH, DOC and organic matter contents. The study primarily focussed on predicting soil and soil solution metal concentrations from the data on total soil metal concentrations (HNO3 extracts) and soil and soil solution properties (pH, DOC and organic matter content). We tested the multiple regression models proposed by Tipping et al. (2003) to predict heavy metal concentrations in soil solutions and the results indicated a better fit (higher R2 values) in both studies for Pb compared to the Zn and Cu concentrations. Both studies observed consistent negative relationships of metals with pH and loss on ignition (LOI) suggesting an increase in soil solution metal concentrations with increasing acidity. The positive relationship between Pb concentrations in porewater and HNO3 extracts was similar for both studies, however, similar relationships were not found for the Zn and Cu concentrations because of the negative coefficients for these metals in our study. The results of this study conclude that the predictive equations of Tipping et al. (2003) may not be applicable to the field sites where the range of DOC and metal concentrations is much lower than their study. Our study also suggests that the extent to which metals are partitioned into soil solution is lower in soils with a higher organic matter contents due to binding of these metals to soil organic matter.

Kinetics and Equilibrium of Fe3+ Ions Adsorption on Carbon Nanofibers

Generally, the interaction between metal ions and adsorbent is governed by many factors including; concentration of metal ions, interaction time and solution pH. In this work, we applied liquid phase adsorption for studying the interaction between Fe3+ ions and Carbon Nanofibers (CNFs) irradiated by ultrasonic waves. Kinetics and isotherms model of the Fe3+ ion adsorption was investigated by varying contact time and pH. We found that the Fe3+ ions were efficiently adsorbed on CNFs for 0.5 h in acidic pH of around 5. In order to obtain the best-fitted isotherms model, Langmuir and Freundlich’s isotherms were used in this work. The adsorption equilibrium Fe3+ metal ions on CNFs tend to follow Langmuir. Adsorption kinetics of Fe3+ ions on CNFs were investigated by using both pseudo-first and pseudo-second orders. The adsorption kinetics coincided well with the pseudo-second-order.

Effect of Organic Matter Amendment on Lead Contamination in Roadside Soil and Plant

Lad Contamination in Roadside Soil and Plant and Effect of Organic Matter Amendment (Sabaruddin, D Budianta and Mardia): Roadside soils and plants may be the most important sink of lead (Pb). It has been widely known that soil organic matter (SOM) plays important roles in determining concentrations of metals in soil solution and their extractability from the soil. To investigate Pb contamination in the roadside soils and plants, as well as the effect of organic matter (OM) on the soluble Pb in the roadside soils, surface soils (0 to 20 cm) were collected from a busy road. The soils were incubated for 4 weeks under room temperature after being treated with 0, 30, 60 and 90 Mg ha-1 of OM. Leaves of oil palms (Elaeis guineensis) planted on the roadside were also analyzed for Pb content. Current study revealed that Pb content in roadside soils and leaves of oil palm was 1.5 and 5.5 times higher than the safe level of Pb in soil and plant. It confirms that both soil and plant at the study site were contaminated by Pb. Current study also showed that SOM amendment significantly (P<0.01) affected soluble Pb content in the soils. Adding OM to the soil at 30 Mg ha-1 to correct the level of SOC from very low to low was sufficient to significantly reduce soluble Pb in the soils. However, the application of 60 Mg ha-1 of OM triggered the increases in soluble Pb in the soils. Further increases in OM application to 90 Mg ha-1 resulted in significant increases in soluble Pb as compared with that in the soil receiving 30 Mg ha-1 of OM. In spite of the increases, the level of soluble Pb in the soils receiving 60 and 90 Mg ha-1 of OM was still much below the safe level of Pb in soil.

Effect of Sol Concentration, Aging and Drying Process on Cerium Stabilization Zirconium Gel Produced by External Gelation

Cerium Stabilized Zirconium gel has been prepared using external gelation process. As the raw materials was used ZrO(NO3)2 and Ce(NO3)4 nitrate salt which was dissolved with water into Zr-Ce nitrate mixture. The concentration of the nitrate salt mixture in the sol solution was varied by varying the concentration of zirconium and cerium nitrate in the sol solution and the addition of PVA and THFA to produce a sol with a viscosity of 40-60 cP. The viscosity range of 40-60cP is the viscosity of the sol solution that was easy to produce a good gel in the gelation apparatus. Sol solution was casted in a gelation column equipped with following tools: a 1 mm diameter drip nozzle which was vibrated to adjust the best frequency and amplitude of vibration, a flow meter to measure the flow rate of sol, flowing of NH3 gas to presolidification process. Gelation column was contained NH4OH solution as gelation medium and gel container to collect gel product. Gel obtained from the gelation process than processed with ageing, washing, drying and calcinations to get round gel and not broken at calcinations up to 500°C. The parameters observed in this research are variation of Zr nitrate concentration, Ce nitrate concentration, ratio of Zr and Ce in the sol and ageing and drying process method which was appropriate to get a good gel. From the gelation processes that has been done, it can be seen that with the presolidification process can be obtained a round gel and without presolidification process, produce not round gel. In the process of ageing to get not broken gel, ageing was done on the rotary flask so that during the ageing, gels rotate in gelation media. Gels, then be washed by dilute ammonium nitrate, demireralized water and iso prophyl alcohol. The washed gel was then dried by vacuum drying to form pores on the gel which become the path for the gases resulting from decomposition of the gel to exit the gel. Vacuum drying can prevent cracking because the pores allow the gel to release the decomposition of the material during heating. Larger the concentration of nitric metal in sol solution, yields a gel with a larger diameter of gels. This research allows us to plan the diameter of the sintered particles to be made.

One-Step Carbon Coating and Polyacrylamide Functionalization of Fe₃O₄ Nanoparticles for Enhancing Magnetic Adsorptive-Remediation of Heavy Metals.

Magnetic nanoparticles are used in adsorptive removal of heavy metals from polluted wastewater. However, their poor stability in an acidic medium necessitates their protection with a coating layer. Coating magnetic nanoparticles with carbon showed proper protection but the heavy metal removal efficiency was slightly weak. However, to boost the removal efficiencies of surface functionalization, polyacrylamide was applied to carbon-coated Fe3O4 nanoparticles. In this paper, to facilitate the synthesis process, one-step carbon coating and polyacrylamide functionalization were conducted using the hydrothermal technique with the aim of enhancing the adsorptive removal capacity of Fe3O4 nanoparticles towards some heavy metals such as Cu(II), Ni(II), Co(II), and Cd(II). The results showed that the one-step process succeeded in developing a carbon coating layer and polyacrylamide functionality on Fe3O4 nanoparticles. The stability of the magnetic Fe3O4 nanoparticles as an adsorbent in an acidic medium was improved due to its resistance to the dissolution that was gained during carbon coating and surface functionalization with polyacrylamide. The adsorptive removal process was investigated in relation to various parameters such as pH, time of contact, metal ion concentrations, adsorbent dose, and temperature. The polyacrylamide functionalized Fe3O4 showed an improvement in the adsorption capacity as compared with the unfunctionalized one. The conditions for superior adsorption were obtained at pH 6; time of contact, 90 min; metal solution concentration, 200 mg/L; adsorbent dose, 0.3 g/L. The modeling of the adsorption data was found to be consistent with the pseudo-second-order kinetic model, which suggests a fast adsorption process. However, the equilibrium data modeling was consistent with both the Langmuir and Freundlich isotherms. Furthermore, the thermodynamic parameters of the adsorptive removal process, including ΔG°, ΔH°, and ΔS°, indicated a spontaneous and endothermic sorption process. The developed adsorbent can be utilized further for industrial-based applications.

Defining appropriate methods for studying toxicities of trace metals in nutrient solutions

The use of inappropriate experimental conditions for examining trace metal phytotoxicity results in data of questionable value. The present study aimed to identify suitable parameters for study of phytotoxic metals in nutrient solutions. First, the literature was reviewed to determine the concentration of six metals (Cd, Cu, Hg, Ni, Pb, and Zn) from solution of contaminated soils. Next, the effects of pH, P, Cl, NO3, and four Fe-chelators were investigated by using thermodynamic modelling and by examining changes in root elongation rate of soybean (Glycine max cv. Bunya). The literature review identified that the solution concentrations of metals in soils were low, ranging from (µM) 0.069–11Cd, 0.19–15.8 Cu, 0.000027–0.000079 Hg, 1.0–8.7 Ni, 0.004–0.55 Pb, and 0.4–36.3 Zn. For studies in nutrient solution, pH should generally be low given its effects on solubility and speciation, as should the P concentration due to the formation of insoluble phosphate salts. The concentrations of Cl, NO3, and various chelators also influence metal toxicity through alteration of metal speciation. The nutrient solutions used to study metal toxicity should consider environmentally-relevant conditions especially for metal concentrations, with concentrations of other components added at levels that do not substantially alter metal toxicity.

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

Metal-salt amended soils (MA, n = 23), and historically-contaminated urban soils from two English cities (Urban, n = 50), were investigated to assess the effects of soil properties and contaminant source on metal lability and solubility. A stable isotope dilution method, with and without a resin purification step, was used to measure the lability of Cd, Cu, Ni, Pb and Zn. For all five metals in MA soils, lability (%E-values) could be reasonably well predicted from soil pH value with a simple logistic equation. However, there was evidence of continuing time-dependent fixation of Cd and Zn in the MA soils, following more than a decade of storage under air-dried conditions, mainly in high pH soils. All five metals in MA soils remained much more labile than in Urban soils, strongly indicating an effect of contaminant source on metal lability in the latter. Metal solubility was predicted for both sets of soil by the geochemical speciation model WHAM-VII, using E-value as an input variable. For soils with low metal solution concentrations, over-estimation of Cd, Ni and Zn solubility was associated with binding to the Fe oxide fraction while accurate prediction of Cu solubility was dependent on humic acid content. Lead solubility was most poorly described, especially in the Urban soils. Generally, slightly poorer estimation of metal solubility was observed in Urban soils, possibly due to a greater incidence of high pH values. The use of isotopically exchangeable metal to predict solubility is appropriate both for historically contaminated soils and where amendment with soluble forms of metal is used, as in toxicological trials. However, the major limitation to predicting solubility may lie with the accuracy of model input variables such as humic acid and Fe oxide contents where there is often a reliance on relatively crude analytical estimations of these variables.Trace metal reactivity in urban soils depends on both soil properties and the original source material; the WHAM geochemical model predicts solubility using isotopically exchangeable metal as an input.

Role of Solution Chemistry in Composition of Lithium-Ion Battery Precursors

Coprecipitation is a popular method to synthesize precursors for lithium-ion battery active materials because it is easy to implement in the lab, fast, scalable, and adaptable to a variety of transition metal compositions. In addition, coprecipitation provides routes to control and modify precursor and resulting final active material particle morphology, resulting in battery materials with tunable size, shape, and polydispersity. In many cases, especially under conditions where morphology control or tunability is desirable, the coprecipitation is run under conditions of either low transition metal concentration in solution and/or conditions where significant fractions of the transition metals stay soluble in the solution. Within these solution environments the composition of the resulting battery precursor particles can deviate from the solution feed conditions, a consequence not often designed for or reported in the battery material synthesis literature but which can significantly influence the resulting composition and thus electrochemical properties of the final active material. In this talk, efforts will be described in our lab to understand the solution environment during coprecipitation of battery particles with the final goal of explicit control over the composition of the resulting precursor particles both with regards to composition and structure. Insights from probing the rate at which transition metals are deposited onto the precipitate particles will also be presented.

Use of Zeolite Rocks in Metal Recovery from Mine Water

Mine water at some mineral deposits in Transbaikalia contains valued metals commercially recoverable from solutions using zeolite rocks. Experimental impregnation of metal-bearing mine water from Sherlovaya Gora and Bom-Gorphon areas with sodium and ammonium kinds of clinoptilolite rocks from shivyrtuin deposit has been carried out. In the laboratory conditions, metals adsorbed by zeolite rocks are extracted by means of displacement by concentrated ammonium salts with further calcinations of the filtrate up to 500 °С. The metal content of the obtained cakes is conditioned by metal concentrations in solutions, by methods of impregnation and by the eluents applied. Saturation of ammonium types of zeolites with mine water solutions from the Sherlovaya Gora lake and further extraction of adsorbed metals by ammonium acetate yields the recovery of lantanoids of 73%. The obtained results, considering multiple recycling of the sorbent, can be used in development of an efficient technology for extraction of rare earth elements from mine solutions.

Turning Waste drilling fluids into a new, sustainable soil resources for landscaping

Waste drilling fluids (WDF) is a complex mixture of different additives with different chemical and biologic properties, which have no biodegradability and seriously pollute the soil system without any disposal. After the later stage treatments, like landfill and solidification, waste drilling fluids also have potential detrimental to the environment and health. In this paper, a formula has been studied that can turn the waste water-based drilling fluids into an environment friendly soil. The treatment process can realize the harmless disposal and effective utilization of water-based drilling wastes. In the laboratory column study, by assessing the germination time and growth of ten kinds of plants which were grown on the high quality soil mixture with the waste drilling fluids (10:1, wt:wt), the Festuca arundinacea seed was selected to evaluate the quality of the soil. The formulas were used as a treatment agent mixing with drilling wastes collected from drilling well sites in Dagang, Tianjing, China with design of orthogonal experiment. The analysis was comprised of evaluation of heavy metals, chemical oxygen demand (COD), soluble salt content, and pH. The formula (20%coal+10%solid sludge +5%chips) was proposed as a low-cost strategy to reduce leaching of toxic elements, and improve plant establishment. The concentrations of heavy metals in leachate solution exacting from the soil were lower than the EPA toxicity limit set by USEPA. The pH was approximately 7∼8. COD was less than 100mg O2/L and the soluble salt content was less than 25g/kg. In the Field application, the environment friendly formula developed in this study has been successfully applied to Dagang Oilfield. The treated waste drilling fluids are favorable to the growth of the plants (the soil organic matter is more than 30g/kg, the porosity is more than 50%). The treatment process is easy to handle, low-cost (<100RMB/m3) and realizes a new, sustainable soil resources for landscaping.

Raman transduction for polymeric ion-selective sensor membranes: Proof of concept study

A novel technique for indirect metal ions detection with micro-Raman spectroscopy is proposed. Plasticized polymeric membranes typically applied for construction of ion-selective electrodes were employed to obtain Raman spectra as analytical signal. The latter is derived from evolution of Raman spectrum of lipophilic ligand incorporated into sensor membrane upon a contact with sample solutions. It is demonstrated that the membrane Raman spectrum depends on the metal concentration in sample solution. This is due to the metal binding by ligand at the membrane surface. Moreover, the observed spectral changes can be related to metal content through multivariate modelling (partial least squares regression). This feasibility study opens a potentially new field consisting of the application of micro-Raman spectroscopy for indirect analysis of ions in micro volumes of the samples (10μL).

Comparison of Rhodotorula sp. and Bacillus megaterium in the removal of cadmium ions from liquid effluents

AbstractThis study compares the capacity ofRhodotorulasp. andBacillus megateriumfor Cd(II) removal considering the influence of operating parameters (pH, biosorbent dosage, contact time, temperature, initial metal concentration in solution). The highest Cd(II) uptake of 14.2 mg/g byRhodotorulasp. was exhibited at 30°C, when working at pH 6 and with 5 g/l biosorbent dosage, after 48 h of contact time. In these conditions, a removal efficiency of 85% was obtained. Similar outcomes were obtained forB. megaterium(15.1 mg/g, 90%) at 35°C, pH 4 and 3 g/l biosorbent dosage, considered as the optimum set of parameters, equilibrium being achieved for a contact time of 20 min. The possible interaction mechanisms between the biosorbents and Cd(II) were evaluated through point of zero charge (pHpzc), Fourier transform infrared (FTIR), spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX). Data were modeled using pseudo-first and pseudo-second order kinetic models and Langmuir and Freundlich isotherms models. Further studies considered a modeling approach based on linear regression with Durbin-Watson statistics, while the accuracy and precision of experiments were evaluated by ANOVA.

Development of electrostatic-based bioavailability models for interpreting and predicting differential phytotoxicity and uptake of metal mixtures across different soils

Metals are ubiquitous and normally co-occur as mixtures in soil, but there remains much to do regarding the development of appropriate models which incorporate mixture interactions and bioavailability to estimate their phytotoxicity and phytoaccumulation. Here, we developed a probability-based electrostatic toxicity model (ETM) and a Langmuir-type electrostatic uptake model (EUM) to predict and normalize toxicity and uptake of zinc-copper mixtures in Hordeum vulgare L. in different soils. For model development, the electrical potential (ψ0) and metal ion activities ({M2+}0) at the cell-membrane surface was computed based on plant physiological properties and soil solution chemistry. Single metal toxicity correlated more closely to their corresponding {M2+}0 than to ion activities in soil solution or total soil metal concentrations. The ETM explained up to 89% of the variance in mixture toxicity across different soils. Incorporation of ψ0 into the EUM improved the model's ability for predicting metal uptake. Besides, cell-surface H+ appeared to significantly inhibit copper uptake via competition or other mechanisms, beyond its effect upon ψ0. Our results for the first time demonstrate that electrostatic theory can be used to predict and reconcile mixture toxicity and uptake data in different soils, indicating the potential of electrostatic-based models in risk assessment of multimetal-contaminated soils.

Preparation of platinum-modified boron-doped diamond for electroreduction of CO2

Metal-modified boron-doped diamond has been prepared for preliminary study of CO2 electroreduction. Pt was electrodeposited at boron-doped diamond (BDD) by using chronoamperometry technique. The precursor metal solution concentration of 6 mM was applied with deposition potentials of -0.3 V (vs Ag/AgCl). Characterization by using FESEM and XPS confirmed the presence of Pt on the surface of BDD. Cyclic voltammetry was applied to obtain an optimum condition for electroreduction of CO2. CO2 dissolved in 0.1 M NaCl and 0.1 M Na2SO4 solutions were applied. A reduction peak, attributable to CO2, appeared at a potential of -0.7 V (vs Ag/AgCl) in NaCl solution, while no peak was observed in Na2SO4 solution. The result indicated that the metal-modified electrodes has successfully prepared as a working electrode for CO2 electroreduction.

Tolerance and Removal Mechanisms of Heavy Metals by Fungus Pleurotus ostreatus Haas

Fungus Pleurotus ostreatus Haas can tolerate and remove heavy metals from water. Among three heavy metals tested, the removal of Pb was the most efficient (99.9–100.0%), followed by Cd (45.9–61.1%), and Cr (29.4–64.5%). The uptake of heavy metals by the fungus varied and was dependent on the element. Pb was found to be transported primarily into the fungal cell wall (68.2–91.2% of the total), which was much higher than the insoluble form (20.1–32.7%), and the maximum intracellular concentration of Pb was found to be 119,830.4 mg kg−1. In the cases of Cd and Cr, their insoluble forms were the main products of the reaction with the fungus, which accounted for 30.0–39.1 and 19.6–37.4% of the total. P. ostreatus Haas produces oxalic acid, and this production is stimulated by Pb and Cr but inhibited by Cd. Parallel experimental results indicated that the concentration of the soluble metals in solution decreased with the increase of oxalic acid, which further suggested that oxalic acid played a partial role in the removal of the soluble heavy metals by chelation. These results revealed that this species of fungus has a variety of response mechanisms to the presence of heavy metals in solution.

Phytoextraction Efficiency of Cadmium and Zinc by Arum (&lt;i&gt;Colocasia esculenta&lt;/i&gt; L.) Grown in Hydroponics

Cadmium (Cd) and Zinc (Zn) tolerance and phytoextraction efficiency of arum (Colocasia esculenta L.) were investigated in hydroponics. Plants were grown for 60 d in nutrient solution after addition of Cd and Zn at the levels of 0, 15, 30 and 60 mmol L−1 and 0, 100, 500 and 1,000 μmol L−1, respectively. Growth of arum was unaffected by low levels of metal concentration (15 μmol L−1 Cd and 100 μmol L−1 Zn) whereas it decreased gradually with the increase of metal concentration in solution. Concentration of metals in parts of arum increased significantly (P<0.05) with the levels of metals in growth media. In arum shoots, Cd and Zn concentrations were 713 and 10,120 mg kg−1 respectively, at their low levels in solution. These concentrations (15 μmol L−1 Cd and 100 μmol L−1 Zn) did not cause any growth retardation indicating that arum is a metal hyperaccumulator. Transfer factor (TF) greater than one confirmed the hyperaccumulating behavior of arum for Cd and Zn in solution. Cadmium and Zn uptake in arum shoots without growth retardation and TF of these metals in arum indicates that this plant is a suitable candidate for the phytoremediation of water contaminated with Cd and Zn.