Ratio Of Metal Concentration Research Articles

Amphiphilic triblock copolymer-assisted synthesis of hierarchical NiCo nanoflowers by homogeneous nucleation in liquid polyols

Rose-like NiCo nanoflowers were synthesized by homogeneous, one-pot polyol reduction of Ni and Co-acetates in presence of an amphiphilic triblock copolymer and KOH. 1,2-propanediol was used as solvent-cum-reducing agent as no external reducing agent was found to be necessary in this process. Detailed x-ray diffraction and morphological characterizations confirmed formation of fcc hierarchical NiCo nanoflowers containing 2D nanosheet-like subunits (thickness of about 30nm) with an average diameter of ~700nm. Amphiphilic polymer played a pivotal role in the growth of nanorose as it favored a preferential growth of nanocrystals along a particular crystal plane as was observed in transmission electron microscopy. Effects of other parameters like use of hydrophilic polymer, surfactants, ratio of initial metal concentrations, choice of polyol media and concentration of KOH on the morphology of nanoflowers were also investigated. Room temperature magnetic studies revealed higher saturation magnetization and low coercivity (108.6emu/g and 78.4Oe) of nanorose. Based on LaMer model, a kinetically-controlled growth mechanism for the formation of NiCo nanorose is also proposed.

Impacts of human activities and sampling strategies on soil heavy metal distribution in a rapidly developing region of China

The impacts of industrial and agricultural activities on soil Cd, Hg, Pb, and Cu in Zhangjiagang City, a rapidly developing region in China, were evaluated using two sampling strategies. The soil Cu, Cd, and Pb concentrations near industrial locations were greater than those measured away from industrial locations. The converse was true for Hg. The top enrichment factor (TEF) values, calculated as the ratio of metal concentrations between the topsoil and subsoil, were greater near industrial location than away from industrial locations and were further related to the industry type. Thus, the TEF is an effective index to distinguish sources of toxic elements not only between anthropogenic and geogenic but also among different industry types. Target soil sampling near industrial locations resulted in a greater estimation in high levels of soil heavy metals. This study revealed that the soil heavy metal contamination was primarily limited to local areas near industrial locations, despite rapid development over the last 20 years. The prevention and remediation of the soil heavy metal pollution should focus on these high-risk areas in the future.

Hyperaccumulators of mercury in the industrial area of a PVC factory in Vlora (Albania)

Contamination by heavy metals is one of the major threats to soil and water as well as human health. Much at- tention is being paid to metal-accumulating plants that may be used for the phytoremediation of contaminated soils. Some plants can accumulate remarkable levels of metals, 100-1000-fold the levels normally accumulated in most species. This study evaluated the potential of mercury accumulation of 17 plant species growing on contaminated sites in the ex- in- dustrial area of the PVC Factory, Vlora, Albania. Plant roots, shoots and soil samples were collected and analyzed for the selected metal concentration values. The biological accumulation coefficient (BAC) was calculated to evaluate the potential use of plant species for phytoremediation purposes. The concentration of Hg in soils inside the contaminated area varied from 45-301 mg/kg -1 . The concentration of Hg in plant shoots and roots varied from 0.1 to 12.9 mg/kg -1 and 0.1 to 4.2 mg/kg -1 , respectively. Species Medicago sativa L. and Dittrichia viscosa (L.) W. Greuter were found to be the most suitable plants for phytoremediation of the site contaminated with mercury (BAC values varied from 30-10 percent, respectively). Considering the BAC values, none of the plant species was found to be a hyperaccumulator; however, plants with high BCF (metal concentration ratio of plant root to soil) and low BTC (metal concentration ratio of plant shoots to roots) have the potential for phytostabilization and phytoextraction. The results of this study can be used for the management and decon- tamination of soils with mercury using plant species having phytoremediation potential/characteristics.

Neural network model prediction of chromium separation in polyelectrolyte-enhanced ultrafiltration

Effectiveness of polyelectrolyte-enhanced ultrafiltration in chromium recovery from its aqueous solutions was tested experimentally. Two chromium species, Cr(III) and Cr(VI) ions, were the subject of ultrafiltration processes enhanced with two water-soluble, ion-exchanging polyelectrolytes. These were: poly(sodium 4-styrenesulfonate) - PSSS (for Cr(III) ions recovery) and poly(diallyldimethylammonium chloride) - PDDAC (for Cr(VI) ions recovery). Experimental ultrafiltration tests with two different membranes and model solutions of appropriate chromium ions (5 and 50 mg dm -3 ), at different pH and with various polyelectrolyte doses, provided numerical data for the artificial neural networks training procedure. Numerical neural network models made prediction of chromium retention coefficient (R) under different process conditions (pH, polymer dose, concentration of selected Cr form) possible. Strongly nonlinear dependences of retention coefficient (R) on pH and polymer : metal concentration ratio for both chromium species, represented by experimental data, were identified and modeled by neural networks correctly. Good compatibility between experimental data and neural network predictions was observed.

Bioaccumulation and Translocation of Arsenic in the Ecosystem of the Guandu Wetland, Taiwan

High arsenic (As) levels occur naturally in geothermal areas, potentially polluting downstream wetland ecosystems. The study was to determine the distribution of As among aqueous, solid, and plant phases in the Guandu Wetland of Taiwan. Chemical compounds (As, Fe, Mn, TOC, SO4 2-, and FeS2) and isotopic compositions (δ34S) in water and soil samples were analyzed to characterize the As distribution. The sequential extraction of As and total As in plant samples wasanalyzed to estimate the bioconcentration factor (BCF) and translocation factor (TF; defined as the ratio of metal concentration in the shoots to those in the roots) of As in Kandelia obovata in aqueous and solid phases. The As concentrations in plants (23.69 mg/kg) were higher than in the surrounding water (0.0018 mg/L) and soils (17.24 mg/kg). Kandelia obovata have high As bioavailability and low TF, causing easy adaptation to grow in As-contaminated wetland ecosystems. BCFplants/water (13657.92) was higher than BCFplants/soil (1.38). The uptake and bioaccumulation of As in Kandelia obovata are significant; therefore, Kandelia obovata is an As accumulator. The uptake As by the Kandelia obovata plant might depend on the oxidation of As-contained FeS2 in the aerial roots and/or adsorption of As on root surface.

MOBILITY OF HEAVY METALS IN PLANTS AND SOIL: A CASE STUDY FROM A MINING REGION IN CANADA

Understanding the dynamic of metals in soil and plantsis essential for ecosystem management and risks assessment of environmental pollution and sustainability.The main objective of the present study is to determine the mobility of Ni, Cu, Fe, Mg and Zn in soil and their translocation in D. cespitosa plants in a mining region in Northern Ontario.The total amount of Cu, Ni, Fe, Mg and Zn were significantly higher in the top horizon (LFH) compared to the adjacent layer Ae. The vertical distribution of metals in soil varied with the type of metals. The results of this study indicated that only a small portion of total metal was bioavailable to plants. The enrichment factor values for the targeted elements were far above the value of contamination resulting in high availability and distribution of metals in soil. The average bioconcentration/bioaccumulation factors (metal concentration ratio of plant roots to soil) was high and varied from 3.1 to 40 for Cu, 24.5 to 91.6 for Fe, 18.2 to 398.6 for Mg, 10.3 to 75.5 for Ni and 24.9 to 73 for Zn. The translocation factor values were very low for the five metals. They ranged from 0.05 to 0.46 for Cu, 0.03 to 0.1 for Fe, 0.28 to 1.48 for Mg, 0.15 to 0.38 for Ni and 0.68 to 1.16 for Zn. Based on existing classification, Deschampsia. cespitosa is an excluder as it has high levels of metals in the roots but with a shoot/root ratio less than 1. This plant has a high potential for phytoextraction of metals from Northern Ontario soils.

Numerical simulation and experiment in the systems of labile complexes of metals. Silver reduction from the thiourea electrolyte

Voltammograms of silver reduction from complex thiourea electrolytes with the ligand to metal concentration ratio varied from 1 to 50 were measured on the freshly prepared surface of silver electrode. The results were analyzed using the numerical model of this electrode process which takes into account homogeneous chemical reactions proceeding in solution, diffusion–migration transfer of the species present in solution, and electrode reactions participated by electroactive components of the electrolyte. We estimated the values of standard exchange current density for partial electrode reactions in which silver complexes with different number of ligands can take part. The highest electrochemical activity is exhibited in solutions with the low concentration of complex-forming agent – by silver aqua complexes, while in solutions with high thiourea concentration – by silver complexes with one ligand. It was found that kinetic hindrances to discharge of the thiourea silver complexes unlikely to be due to the adsorption of thiourea molecules blocking the growth sites or to the adsorption of complex silver ions. The results admit interpretation of the mechanism of electrode process either from the viewpoint of simultaneous discharge of all the complex silver ions present or from the viewpoint of discharge of silver complex with one ligand in combination with rapid chemical reactions of dissociation of other, non-discharging silver complexes.

Natural contamination by As and heavy metals in soil, their bio-accumulation and potential sources: the case of a travertine limestone quarry, Greece

AbstractThe first mineralogical and geochemical investigation of the travertine limestone, soil and corresponding plants associated with the Neogene basin of Varnavas, NE Attica, revealed a significant enrichment in the metalloid As. The total concentrations of As ranged from 61 to 210 ppm in limestone and 33 to 430 ppm in the associated soil demonstrating a wide variation of values. Calcite is a common authigenic mineral within travertine limestone, forming fine uniform micritic aggregates, having As and Mg concentrations lower than detection limits of EDS analysis. Clastic dominated minerals are quartz (both fine- and coarse-grained), muscovite, clinochlore, illite, pyrite, galena, arsenides, rutile, sphene, zircon, REE-minerals and albite. Goethite and Fe-Mn-oxides occur between calcite grains. The presence of fossilized micro organisms, resembling foraminifera, in travertine limestone combined with hydrous Fe-Mn-oxides, suggests a possible marine transgression during the evolution of the basin.The As content in plants ranges from 1.1 to 28 ppm As in shoots, and 0.8 to 114 ppm As in roots. The translocation factor, which is defined as the ratio of metal concentration in the shoots to the roots, is relatively low (average 0.33%) suggesting that the internal transport of metals from the roots to shoots was restricted. The bioaccumulation factor, which is defined as the ratio of metal concentration in the plants to that in soil, exhibits a wide range from relatively low (5.2–9.0% for As, Fe, Cr, Ni and Pb), much higher (56–67% for Cu and Zn) and exceptionally high (160% for Mo). A significant correlation between the translocation factors for Fe and As may confirm that Fe-Mn oxides/hydroxides represent the major sorbing agents for As in soils. The presented data, due to As contamination in travertine limestone, soil and plants, suggest a potential environmental risk not only for that part of Greece but in general for similar depositional environments.

Toxic elements mobility in coal and ashes of Figueira coal power plant, Brazil

During operation, the coal power plant produces solid waste (bottom and fly ash) and uncontrolled ashes disposal could lead to environmental contamination. Major and trace elements (Al, Fe, Ti, Ca, Mg, As, Cd, Cr, Co, Cu, Mn, Mo, Ni, Pb, Zn, V) were determined in coal and ashes of the power plant of Figueira (Brazil) and their mobility evaluated by total and available metal concentration ratio. The total concentration was determined by WDXRF technique and the available concentration (after extraction with EDTA) by ICP-OES technique. The results showed a high total concentration for As and Zn (average 270 and 391mgkg−1) in coal and (average 974 and 1330mgkg−1) in fly ashes. The high mobility of As (>70%), followed by Mo (>55%) and next by Mn, Zn, Cd, Pb (30–5%) in ash can cause environmental impact. Arsenic could be considered the most critical element to be leached from ashes.

Evaluation of cadmium bioaccumulation and translocation by Hopea odorata grown in a contaminated soil

Cadmium (Cd) contamination has an adverse effect on soil productivity and crop production. Phytoremediation is a long term and environmental friendly technology to remediate Cadmium polluted areas. This study was conducted to evaluate the potential of Hopea adorata for remediation of soils contaminated with Cd. Plant seedlings were planted in a clayey soil spiked contaminated with Cd in the amount of 0, 25, 50, 75, 100 and 150 mg kg -1 named as; Cd0, Cd 1 , Cd 2 , Cd 3 , Cd 4 and Cd 5 for a period of five months. The highest growth performance was recorded in the control (Cd 0 ). Cd concentrations among plant parts were in the following trend: roots>stems>leaves. In order to evaluate the potential of species selected as phytoremediator, three indicators were used namely, bioconcentration factor (BCF, the metal concentration ratio of plant roots to soil), translocation factor (TF, the metal concentration ratio of plant shoots to roots) and removal efficiency (RE, total concentrations of metal and dry biomass of plants to total loaded metal in growth media). The highest total Cd concentration (290.23 ± 13.38 mg kg -1 ) and Cd removal efficiency (0.81± 0.06%) were found in Cd 5 and Cd 1 , respectively. Cd 2 exhibited the maximum total dry biomass (60.88 ± 1.78 g). H. odorata showed high BCFs (>1) and low TFs (<1). It can be concluded that this species is suitable to be used in phytoremediation of Cd-contaminated. For further confirmation, an evaluation under field condition will be needed. Keywords: Phytoremediation, Hopea odorata , heavy metals, soil pollution, removal efficiency African Journal of Biotechnology Vol. 11(29), pp. 7472-7482, 10 April, 2012

Segmented sediment probe for diffusive gradient in thin films technique

A new modification of a constrained sediment probe was tested for application in the diffusive gradient in thin films technique (DGT). The sediment probes packed with agarose based resin and diffusive gels were exposed under laboratory conditions to well-mixed test solutions of cadmium and nickel as model elements. The reproducibility of metal uptake in segments (strips) of resin gel with anchored 8-hydroxyquinoline functional groups (Spheron-Oxin® ion exchanger) was studied. The relative yield of uptake of metals in resin gel strips, determined as the ratio of the time-averaged DGT-measured metal concentration and the concentration of a metal in the test solution, showed that the effective sampling area was larger than the geometric area of the resin gel strip. This relative yield is in very good agreement with the theoretical value obtained by the Finite Element Method (FEM) in calculation of diffusion processes. The performance of the modified constrained probe is demonstrated by an example of uranium, iron and manganese depth profiling in a spiked sediment core. Utilization of the new segmented sediment probe in the DGT technique is very simple. Its application does not require special devices and labor-intensive procedures. It can provide sediment depth profiles of metals with the resolution down to the millimetre level.

Galvanic Wastewater Treatment by Means of Anionic Polymer Enhanced Ultrafiltration

Galvanic Wastewater Treatment by Means of Anionic Polymer Enhanced Ultrafiltration This work is focused on polyelectrolyte enhanced ultrafiltration as an effective heavy metal separation technique. Three types of effluents, containing Zn(II), Cu(II) and Ni(II) ions, were subjected to the separation process. Poly(sodium 4-styrenesulfonate) - PSSS, a water soluble anionic polyelectrolyte was used as a metal binding agent. Two Sepa® CF (Osmonics) membranes: EW, made of polysulfone and a modified polyacrylonitrile membrane MW, were used in the ultrafiltration process. The preliminary UF tests were carried out on model solutions with target metal ion concentrations of 10, 100 and 250 mg dm-3. The main parameters affecting the metal retention (the polyelectrolyte quantity and solution pH) were examined. The values of pH 6 and polymer : metal concentration ratio CPSSS : CM = 7.5 : 1 (mol of mer unit per mol of metal) were selected to perform the galvanic wastewater ultrafiltration-concentration tests. Three types of wastewater containing Zn(II), Ni(II) and Cu(II) ions within the concentration range of 30÷70 mg dm-3 were used in the investigations. Very high metal retention coefficients, up to &gt; 99%, were achieved. The retentates obtained were subjected to the decomplexation-ultrafiltration (pH = 1) and subsequent diafiltration step, which enabled partial recovery of concentrated metal ions and the polyelectrolyte. The recovered polyelectrolyte was reused toward Ni(II) ions and the high effectiveness of metal separation has been achieved.

Analysis of Long-range Transported and Local Air Pollution with Trace Metal Concentration Ratio and Lead Isotope Ratio in Precipitation

Analysis of Long-range Transported and Local Air Pollution with Trace Metal Concentration Ratio and Lead Isotope Ratio in Precipitation

HEAVY METAL CONTAMINATION OF SOIL AND RICE IN WASTEWATER-IRRIGATED PADDY FIELD IN A SUBURBAN AREA OF HANOI, VIETNAM

The present paper deals with the heavy metal contamination of soil and rice grain in the paddy field subjected to the irrigation water polluted with wastes from various industrial plants in Hanoi. Soil and rice grain samples were taken at different distances (0-50 m) from the edge of the paddy field. The retention and potential mobility of heavy metals were assessed based on the contents of total and fractionated heavy metals in the soil and their leachability. The concentration of the fractionated heavy metals was determined by selective sequential extraction method. Heavy metal contents in the rice grain were also assessed. The average concentration of the metals in the soil was in the order: Cu (202 mg kg -1 ) > Zn (192 mg kg -1 ). Cr (185 mg kg -1 ) Pb (159 mg kg -1 ) > Ni (45 mg kg -1 ) > Cd (4 mg kg -1 ). The heavy metal concentrations in the soil exceeded the permissible level of the Vietnamese standard for Cd, Cu, Pb and Zn. The results of selective sequential extraction procedure indicated that dominant fractions were oxide, organic and residual materials for Cd, Ni, Pb and Zn, and organic and residual materials for Cr, and an organic material for Cu. Leaching tests with deionized water and acid solutions indicated that the ratio of leached metal concentration to total metal concentration in the soil decreased in the order: Cd > Ni > Cr > Pb > Cu > Zn. By leaching with deionized water and acid solutions, all heavy metals were released fully from exchangeable fraction, and Cd and Ni were fully from carbonate and oxide fractions. The average concentration of heavy metals in the rice grain was in the order: Zn (14.4 mg kg -1 ) > Cu (6.9 mg kg -1 ) > Cr (3.1 mg kw -1 ) > Pb (2.1 mg kg -1 ) > Ni (1.4 mg kg -1 ) > Cd (0.1 mg kg -1 ). The concentrations of Cu, Ni, and Zn in the rice grain met the WHO standard while the concentrations of Cr and Pb exceeded the permissible level of the standard. The concentrations of Cd met the Vietnamese standard while those o.f Pb exceeded the permissible level of the standard. Transfer coefficient for the metals was in the order: Zn > Ni > Cu > Cd ≈ Cr > Pb.

松山，大阪，つくばで観測した浮遊粉じん中金属元素濃度比による長距離輸送と地域汚染特性の解析

松山，大阪，つくばで観測した浮遊粉じん中金属元素濃度比による長距離輸送と地域汚染特性の解析

Prediction of metal-adsorption behaviour in the remediation of water contamination using indigenous microorganisms

In recent years, the adsorption of heavy metal cations onto bacterial surfaces has been studied extensively. This paper reports the findings of a study conducted on the heavy metal ions found in mine effluents from a mining plant where Co(2+) and Ni(2+) bearing minerals are processed. Heavy metal ions are reported to be occasionally present in these mine effluents, and the proposed microbial sorption technique offers an acceptable solution for the removal of these heavy metals. The sorption affinity of microorganisms for metal ions can be used to select a suitable microbial sorbent for any particular bioremediation process. Interactions of heavy metal ions (Co(2+) and Ni(2+)) and light metal ions (Mg(2+) and Ca(2+)) with indigenous microbial cells (Brevundimonas spp., Bacillaceae bacteria and Pseudomonas aeruginosa) were investigated using the Langmuir adsorption isotherm, pseudo second-order reaction kinetics model and a binary-metal system. Equilibrium constants and adsorption capacities derived from these models allowed delineation of the effect of binding affinity and metal concentration ratios on the overall adsorption behaviour of microbial sorbents, as well as prediction of performance in bioremediation systems. Although microbial sorbents used in this study preferentially bind to heavy metal ions, it was observed that higher concentrations (>90mg/ℓ) of light metal ions in multi-metal solutions inhibit the adsorption of heavy metal ions to the bacterial cell wall. However, the microbial sorbents reduced Ni(2+) levels in the mine-water used (93-100% Ni(2+) removal) to below the maximum acceptable limit of 350μg/ℓ, established by the South African Bureau of Standards. Competition among metal ions for binding sites on the biomaterial surface can occur during the bioremediation process, but microbial sorption affinity for heavy metal ions can enhance their remediation in dilute (<5mg/ℓ heavy metal) wastewaters.

Cadmium(II), Lead(II), and Zinc(II) Ions Coordination ofN,N′-(S,S)Bis[1-carboxy-2-(imidazol-4yl)ethyl]ethylenediamine: Equilibrium and Structural Studies

The binding ability of cadmium(II), lead(II), and zinc(II) with N,N′-(S,S)bis[1-carboxy-2-(imidazol-4yl)ethyl]ethylenediamine (BCIEE) and the structure of the formed complexes have been investigated, in aqueous solution, by potentiometry and 1H NMR and 13C NMR spectroscopy for the first time. Stability constants for the cadmium, lead, and zinc complexes with BCIEE were studied by glass electrode potentiometry (GEP) at a fixed total ligand to total metal concentration ratios, varied pH values at (25.0 ± 0.1) °C, and an ionic strength of 0.1 M KCl. For the Cd-BCIEE and Pb-BCIEE systems, three species, MH2L, MHL, and ML, were identified. For the Cd-BCIEE system, the overall stability constants values are 20.63 ± 0.02, 14.78 ± 0.01, and 8.22 ± 0.02, respectively. For the Pb-BCIEE system, the overall stability constants values are 19.71 ± 0.02, 13.78 ± 0.02, and 6.63 ± 0.02, respectively. For the Zn-BCIEE system, two species, ZnH2L and ZnL, were identified, and the overall stability constants values are 21.84 ...

ACCUMULATION OF HEAVY METALS PB, CU, AND ZN IN THE MANGROVE FOREST OF MUARA ANGKE, NORTH JAKARTA

In this study, the concentrations of three kinds of heavy metals, namely Pb, Zn, and Cu from 3 species of mangrove that grow in Muara Angke were measured and analyzed. Our result showed that substrate of mangrove ecosystem in Muara Angke was dominated by clay (30.5% - 62.4%), silt (21.7% -35.6%), and sand (2% -39.5%). The heavy metals accumulation in roots is higher than in sediment, water and leaves with concentration of Zn as the highest. Bioconcentration Factor (BCF; content ratio of heavy metal concentrations in roots or leaves and sediment) and Translocation Factor (TF; ratio of heavy metal concentrations in leaves and roots) of non-essential heavy metals (Pb) is higher in leaves than in roots, but for essential heavy metals (Zn and Cu), the BCF and TF was higher in roots than in leaves. TF values for heavy metals Pb, Cu, and Zn were 0.98-2.59, 0.17-0.51, and 0.52-0.86, respectively. The values of root BCF of those three heavy metals were 0.71-3.17, 0.27-0.74, and 0.95-1.53, while the values of leaf BCF were 1.84-3.45, 0.07-0.34, and 0.72-1.19, respectively. Furthermore, by calculating the phytoremediation (FTD), i.e. the difference between BCF and TF, it is obtained that Sonneratia caseolaris and Avicennia marina can be used in phytoremidiation, with leaves and roots FTD of 1.93 and 2.09, respectively for Sonneratia caseolaris and 1.93 and 1.98 for Avicennia marina.Keywords: heavy metals, mangroves, phytoremidiation, Muara Angke, bioconcentration factor, translocation factor

ACCUMULATION OF HEAVY METALS PB, CU, AND ZN IN THE MANGROVE FOREST OF MUARA ANGKE, NORTH JAKARTA

&lt;p&gt;In this study, the concentrations of three kinds of heavy metals, namely Pb, Zn, and Cu from 3 species of mangrove that grow in Muara Angke were measured and analyzed. Our result showed that substrate of mangrove ecosystem in Muara Angke was dominated by clay (30.5% - 62.4%), silt (21.7% -35.6%), and sand (2% -39.5%). The heavy metals accumulation in roots is higher than in sediment, water and leaves with concentration of Zn as the highest. Bioconcentration Factor (BCF; content ratio of heavy metal concentrations in roots or leaves and sediment) and Translocation Factor (TF; ratio of heavy metal concentrations in leaves and roots) of non-essential heavy metals (Pb) is higher in leaves than in roots, but for essential heavy metals (Zn and Cu), the BCF and TF was higher in roots than in leaves. TF values for heavy metals Pb, Cu, and Zn were 0.98-2.59, 0.17-0.51, and 0.52-0.86, respectively. The values of root BCF of those three heavy metals were 0.71-3.17, 0.27-0.74, and 0.95-1.53, while the values of leaf BCF were 1.84-3.45, 0.07-0.34, and 0.72-1.19, respectively. Furthermore, by calculating the phytoremediation (FTD), i.e. the difference between BCF and TF, it is obtained that Sonneratia caseolaris and Avicennia marina can be used in phytoremidiation, with leaves and roots FTD of 1.93 and 2.09, respectively for Sonneratia caseolaris and 1.93 and 1.98 for Avicennia marina.&lt;/p&gt;&lt;p&gt;Keywords: heavy metals, mangroves, phytoremidiation, Muara Angke, bioconcentration factor, translocation factor&lt;/p&gt;

Accumulation and distribution of cadmium and lead in wheat (Triticum aestivumL.) grown in contaminated soils from the oasis, north-west China

Crops grown in soils contaminated by heavy metals are an important avenue for toxic metals entering the human food chain. The objectives of our study were to investigate the accumulation and distribution of cadmium (Cd) and lead (Pb) in wheat plants cultivated in arid soils spiked with different doses of heavy metal, as well as bioavailability of these metals in the contaminated arid soils from the oasis, north-west China. The concentrations of Cd in the roots of wheat plants were about 5, 14 and 8 times higher than those in the shoots, shells and grains, respectively. The concentrations of Pb in the roots were about 23, 76 and 683 times higher than those in the shoots, shells and grains, respectively. Grains contained 11-14% and 0.1-0.2% of Cd and Pb found in roots of wheat plants. The bioconcentration factor (BCF) is the ratio of metal concentration in plant tissues and metal concentration in their rooted soils. The average BCF of Cd and Pb in grains was 0.6270 and 0.0007. Cd and Pb contents in different parts of wheat plants mainly correlated with the bound-to-carbonate metal fractions in contaminated arid soils. The preliminary study indicated that Cd and Pb were predominantly accumulated and distributed in wheat roots and shoots, and only a small proportion of these metals can reach the grains. The carbonate fractions mainly contributed to Cd and Pb bioavailability in contaminated arid soils.