Phytoextraction of soil trace elements by willow during a phytoremediation trial in Southern Québec,Canada

The phytoextraction of the trace elements (TEs) As, Cd, Cu, Ni, Pb, and Zn by willow cultivars (Fish Creek, SV1 and SX67) was measured during a 3-year field trial in a mildly contaminated soil. Biomass ranged from 2.8 to 4.4 Mg/ha/year at 30,000 plants/ha. Shoots (62%) were the main component followed by leaves (23%) and roots (15%). Biomass was positively linked to soluble soil dissolved organic carbon, K, and Mg, while TEs, not Cd and Zn, had a negative effect. The TE concentration ranking was: Zn > Cu > Cd > Ni, Pb > As, and distribution patterns were: (i) minima in shoots (As, Ni), (ii) maxima in leaves (Cd, Zn), or (iii) maxima in roots (Cu, Pb). Correlations between soil and plant TE were significant for the six TEs in roots. The amounts extracted were at a maximum for Zn, whereas Fish Creek and SV1 extracted more TE than SX67. More than 60% (91–94% for Cd and Zn) of the total TE was in the aboveground parts. Uptake increased with time because of higher biomass. Fertilization, the selection of cultivars, and the use of complementary plants are required to improve productivity and Cd and Zn uptake.     

Trace metal content in the seagrass Cymodocea nodosa: Differential accumulation in plant organs

Differences in the accumulation of seven metallic elements, including micronutrients (Cu, Fe, Mn, Ni and Zn) and non-essential elements (Cd and Pb) among plant organs (leaves, roots and rhizomes) were examined in the seagrass Cymodocea nodosa. Samples were taken from two coastal bays (Catalonia, Western Mediterranean), with a total of nine sampling sites encompassing different levels of metal availability. Metal content was generally higher in uptake organs (leaves and roots) than in rhizomes. However, accumulation in leaves and roots varied between elements. While Cd, Mn and Zn preferentially accumulate in leaves, Fe and Pb accumulate in roots and Cu and Ni in both. There were common spatial (between sites) trends in Cd, Mn, Cu and Zn accumulation in the three organs. However, these spatial trends varied according to the organ considered in the case of Fe, Pb, and Ni. Therefore, assessment of within-plant variability is strongly recommended prior to the use of C. nodosa for biomonitoring purposes, at least for Fe, Pb, and Ni.     

Effects of Municipal Sewage Sludge Doses on the Chlorophyll Contents and Heavy Metal Concentration of Sugar Beet (Beta vulgaris var. saccharifera)

The present study was conducted to assess the suitability of sewage sludge amendment (SSA) in soil for Beta vulgaris var. saccharifera (sugar beet) by evaluating the heavy metal accumulation and physiological responses of plants grown at a 10%, 25%, and 50% sewage sludge amendment rate. The sewage sludge amendment was modified by the physicochemical properties of soil, thus increasing the availability of heavy metals in the soil and consequently increasing accumulation in plant parts. Cd, Pb, Ni, and Cu concentrations in roots were significantly higher in plants grown at 25% as compared to 50% SSA; however, Cr and Zn concentration was higher at 50% than 25% SSA. The concentrations of heavy metal showed a trend of Zn > Ni > Cu > Cr > Pb > Cd in roots and Zn > Cu > Ni > Cr > Pb > Cd in leaves. The only instance in which the chlorophyll content did not increase after the sewage sludge treatments was 50%. There were approximately 1.12-fold differences between the control and 50% sewage sludge application for chlorophyll content. The sewage sludge amendment led to a significant increase in Pb, Cr, Cd, Cu, Zn, and Ni concentrations of the soil. The heavy metal accumulation in the soil after the treatments did not exceed the limits for the land application of sewage sludge recommended by the US Environmental Protection Agency (US EPA). The increased concentration of heavy metals in the soil due to the sewage sludge amendment led to increases in heavy metal uptake and the leaf and root concentrations of Ni, Zn, Cd, Cu, Cr, Pb, and Zn in plants as compared to those grown on unamended soil. More accumulation occurred in roots and leaves than in shoots for most of the heavy metals. The concentrations of Cd, Cr, and Pb were more than the permissible limits of national standards in the edible portion of sugar beet grown on different sewage sludge amendment ratios. The study concludes that the sewage sludge amendment in the soil for growing sugar beet may not be a good option due to risk of contamination of Cr, Pb, and Cd.     

Metal binding properties and structure of a type III metallothionein from the metal hyperaccumulator plant Noccaea caerulescens

Metallothioneins (MT) are low molecular weight proteins with cysteine-rich sequences that bind heavy metals with remarkably high affinities. Plant MTs differ from animal ones by a peculiar amino acid sequence organization consisting of two short Cys-rich terminal domains (containing from 4 to 8 Cys each) linked by a Cys free region of about 30 residues. In contrast with the current knowledge on the 3D structure of animal MTs, there is a striking lack of structural data on plant MTs. We have expressed and purified a type III MT from Noccaea caerulescens (previously Thlaspi caerulescens). This protein is able to bind a variety of cations including Cd(2+), Cu(2+), Zn(2+) and Pb(2+), with different stoichiometries as shown by mass spectrometry. The protein displays a complete absence of periodic secondary structures as measured by far-UV circular dichroism, infrared spectroscopy and hydrogen/deuterium exchange kinetics. When attached onto a BIA-ATR biosensor, no significant structural change was observed upon removing the metal ions.     

Effect of plants on the bioavailability of metals and other chemical properties of biosolids in a column study

The effects of metal-accumulating plants (Salix x reichardtii and Populus balsamifera) on the chemical properties and dynamics of metals in biosolids were investigated using different techniques including diffusive gradients in thin films (DGT), sequential extraction procedures and partitioning coefficient (K(d)). Plants could effectively extract Cd, Ni, and Zn and decreased dissolved organic carbon (DOC). The presence of plants increased the potential bioavailability of these metals, as assessed by an increase in the ratio of metal measured by DGT and metals in the solution. The plants affected the Cd, Ni, and Zn pools (soluble/exchangeable; Fe/Mn oxide and organic matter bound) characterised by sequential extraction and K(d) but did not reduce the total metals in either substrate. However, plants had no effect on Cu, presumably because of the effective buffering of available Cu by organic matter in both solution and solid phases. A high density of plant roots was associated with increased leaching of metals.     

Aquatic and terrestrial plant species with potential to remove heavy metals from storm-water

Remediation of storm-water polluted with heavy metals should be possible in percolation systems, ponds, or wetlands. The aim of this work was to find plant species for such systems that are efficient in the uptake of Zn, Cu, Cd, and Pb. Plants were collected from percolation and wetland areas and analyzed for heavy metal concentrations. Results showed that submersed and free-floating plants had the capacity to take up high levels of Cu, Zn, and Pb into their shoots. With roots having a concentration factor above 1, the terrestrial plants show efficient stabilization of Cd and Zn and emergent plants show corresponding stabilisation of Zn. In addition, Potamogeton natans, Alisma plantago-aquatica, and Filipendula ulmaria were used in a controlled experiment. The shoots of P. natans and the roots of A. plantago-aquatica were found to accumulate even higher concentrations of Zn, Cu, and Pb than found in the field-harvested plants. Similar results were found for Cd in shoots and Pb in roots of F. ulmaria. Our conclusion is that submersed plant species seem to be the most efficient for removal of heavy metals from storm-water.     

Differential response of wheat roots to Cu, Ni and Cd treatment: oxidative stress and defense reactions

Wheat seedlings cv. Zyta were treated with Cu, Ni and Cd at the concentrations causing approximately 50 % root growth inhibition, i.e. 12.5, 50 and 60 μM, respectively. Tissue metal accumulation, membrane permeability, lipid peroxidation, protein oxidation, concentration of thiol compounds as well as protease, glutathione S-transferase (GST) and peroxidase (POD) activities were studied in roots after 7 days of metal exposure. The metals showed different concentrations in root tissues with Cu and Cd being accumulated to the smallest and to the greatest extent, respectively. Membrane permeability was significantly enhanced by Cu and Ni but not by Cd treatment. All metals induced similar increase in protein oxidation, while significant enhancement of lipid peroxidation was observed only in the case of Cu treatment. The detected thiol compounds: cysteine (Cys), homocysteine (Hcy), γ-glutamylcysteine (γ-GluCys) and glutathione (GSH) were differently influenced by the metal treatment. Ni appeared to be the most effective inductor of GSH accumulation while both Cu and Ni similarly increased Cys content in the roots. Accumulation of γ-GluCys was found in response to Cu and Cd applications. Concentration of Hcy was enhanced by Cd treatment but exposure to Ni decreased its content below the level of detection. The activity of GST was considerably elevated by Cd and Ni treatments, while POD activity was increased only in response to Cu application. Our study showed that wheat roots differently responded to treatment with metals used at the concentrations having similar impact on growth.     

Litter N retention over winter for a low and a high phenolic species in the alpine tundra

Mycorrhizal fungus colonization of roots may modify plant metal acquisition and tolerance. In the present study, the contribution of the extraradical mycelium of an arbuscular mycorrhizal (AM) fungus, Glomus mosseae (BEG 107), to the uptake of metal cations (Cu, Zn, Cd and Ni) by cucumber (Cucumis sativus) plants was determined. The influence of the amount of P supplied to the hyphae on the acquisition and partitioning of metal cations in the mycorrhizal plants was also investigated. Pots with three compartments were used to separate root and root-free hyphal growing zones. The shoot concentration of Cd and Ni was decreased in mycorrhizal plants compared to non-mycorrhizal plants. In contrast, shoot Zn and Cu concentrations were increased in mycorrhizal plants. High P supply to hyphae resulted in decreased root Cu concentrations and shoot Cd and Ni concentrations in mycorrhizal plants. These results confirm that some elements required for plant growth (P, Zn, Cu) are taken up by mycorrhizal hyphae and are then transported to the plants. Conversely, Cd and Ni were transported in much smaller amounts by hyphae to the plant, so that arbuscular mycorrhizal fungus colonization could partly protect plants from toxic effects of these elements. Selective uptake and transport of plant essential elements over non-essential elements by AM hyphae, increased growth of mycorrhizal plants, and metal accumulation in the root may all contribute to the successful growth of mycorrhizal plants on metal-rich substrates. These effects are stimulated when hyphae can access sufficient P in soil.     

Effects of Cadmium and Mixed Heavy Metals on Rice Growth in Liaoning,China

Joint effects of Cd and other heavy metals (Pb, Cu, Zn and As) on the growth and development of rice plants and the uptake of these heavy metals by rice were studied using the pot-culture method combined with chemical and statistical analyses. The results showed that the growth and development of rice plants were strongly influenced by the double-element combined pollution. There was an average decrease in the height of rice plants of 4.0–5.0 cm, and grain yield was decreased by 20.0–30.0%, compared with the control. The uptake of Cd by rice plants was promoted due to the interactions between Cd and the other heavy metals added to the soil. The Cd concentration in roots, stems/leaves and seeds increased 31.6–47.7, 16.7–61.5 and 19.6–78.6%, respectively. Due to interactions, uptake of Pb, Cu and Zn by roots and stems/leaves was inhibited, accumulation of Pb, Cu and Zn in seeds was increased, uptake of As by roots was promoted and uptake of As by stems/leaves was inhibited. In particular, the upward transporting ability of the heavy metals absorbed by rice plants was significantly increased.     

微波消解ICP-AES法测定糙苏不同部位中的微量元素

利用微波消解电感耦合等离子发射光谱(ICP-AES)法测定野生中药糙苏根、茎、叶、花和籽中钠、钾、钙、铁、锌、镁、锰、铜、镍、钼、铅和镉的含量,并进行了分析比较。糙苏不同用药部位的微量元素含量存在差异,其中钠、钾、钙、铁、镁在根、茎、叶、花和籽中的含量均较高,锌、锰、铜、镍、钼的含量较少,铅和镉只在根和茎中痕量存在,结果表明糙苏中含有大量人体必需的微量元素,可为进一步探讨糙苏中元素含量与其药效的相关性提供科学的理论依据。     

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.     

Wild Flora of Mine Tailings: Perspectives for Use in Phytoremediation of Potentially Toxic Elements in a Semi-Arid Region in Mexico

The aim of this research was to identify wild plant species applicable for remediation of mine tailings in arid soils. Plants growing on two mine tailings were identified and evaluated for their potential use in phytoremediation based on the concentration of potentially toxic elements (PTEs) in roots and shoots, bioconcentration (BCF) and translocation factors (TF). Total, water-soluble and DTPA-extractable concentrations of Pb, Cd, Zn, Cu, Co and Ni in rhizospheric and bulk soil were determined. Twelve species can grow on mine tailings, accumulate PTEs concentrations above the commonly accepted phytotoxicity levels, and are suitable for establishing a vegetation cover on barren mine tailings in the Zimapan region. Pteridium sp. is suitable for Zn and Cd phytostabilization. Aster gymnocephalus is a potential phytoextractor for Zn, Cd, Pb and Cu; Gnaphalium sp. for Cu and Crotalaria pumila for Zn. The species play different roles according to the specific conditions where they are growing at one site behaving as a PTEs accumulator and at another as a stabilizer. For this reason and due to the lack of a unified approach for calculation and interpretation of bioaccumulation factors, only considering BCF and TF may be not practical in all cases.     

Antifungal potential of binary and mixed-ligand complexes of N,2'-diphenyl acetohydroxamic acid.

Chelating potential of N,2'-DPAHA with 3d metal ions such as Cu(II), Ni(II), Zn(II), and Cd(II) in the presence of Gly and Phen has been investigated. These experiments were designed to study the role of the stability of mixed-ligand complexes in the modulation of its fungicidal potential. The mixed-ligand complexes were found to be more stable than binary complexes. Enhanced stability of mixed-ligand complexes of Ni(II), Co(II), Zn(II), and Cd(II) is presumably due to pi-bonding effects. In the stabilization of the Cu(II) mixed-ligand complex system, the Jahn-Tellar effect may play a vital role, in addition to pi-bonding effects. Fungicidal activity of N,2'-DPAHA and its binary complexes with Cu(II), Ni(II), and Co(II) was examined against Fusarium oxysporum using the inhibition zone technique. Binary complexes of Zn(II) and Cd(II) with N,2'-DPAHA and mixed-ligand complexes M(II)-Gly or Phen-N,2'-DPAHA, where M(II) = Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) were screened against Alternaria alternata by slide germination technique. All mixed-ligand complexes exhibited fungicidal activity but did not improve significantly compared to binary complexes. Synergistic action of primary and secondary ligands has increased the stability of the mixed-ligand complex compared to the binary complex (1:1) of the secondary ligand (N,2'-DPAHA), and the fungicidal potential of the mixed-ligand complex involving N,2'-DPAHA as secondary ligand was not increased.     

Understanding the 7‐Cys module amplification of C. neoformans metallothioneins: how high capacity Cu‐binding polypeptides are built to neutralize host nutritional immunity

Cryptococcus neoformans metallothioneins (MTs), CnMT1 and CnMT2, have been identified as essential infectivity and virulence factors of this pathogen. Both MTs are unusually long Cu‐thioneins, exhibiting protein architecture and metal‐binding abilities compatible with the hypothesis of resulting from three and five tandem repetitions of 7‐Cys motives, respectively, each of them folding into Cu₅‐clusters. Through the study of the Zn(II)‐ and Cu(I)‐binding capabilities of several CnMT1 truncated mutants, we show that a 7‐Cys segment of CnMT1 folds into Cu₅‐species, of additive capacity when joined in tandem. All the obtained Cu‐complexes share practically similar architectural features, if judging by their almost equivalent CD fingerprints, and they also share their capacity to restore copper tolerance in MT‐devoid yeast cells. Besides the analysis of the modular composition of these long fungal MTs, we evaluate the features of the Cys‐rich stretch spacer and flanking sequences that allow the construction of stable metal clusters by adjacent union of binding modules. Overall, our data support a mechanism by which some microbial MTs may have evolved to enlarge their original metal co‐ordination capacity under the specific selective pressure of counteracting the Cu‐based immunity mechanisms evolved by the infected hosts.     

Solution and solid-state studies of complexation of transition-metal cations and Al(III) by aroylhydrazones derived from nicotinic acid hydrazide

Reactions of first series transition-metal cations, Cd(II) and Al(III) with two aroylhydrazones derived from nicotinic acid hydrazide and salicylaldehyde or o-vanillin were studied at 25 °C in buffered dioxane/water 1/1 mixture (pH 5.8) by means of spectrophotometric and spectrofluorimetric titrations. The addition of Mn(II) or Cd(II) ions in hydrazone solutions had no effect on their absorption spectra whereas the addition of Ni(II) and Cr(III) immediately caused precipitation. The reaction of Zn(II) with salicylaldehyde derivative was found to be photosensitive. Relatively high conditional stability constants of 1:1 complexes of Cu(II), Zn(II) and Al(III) with both ligands were determined. Solid complexes of Cu(II), Ni(II) and Zn(II) with aroylhydrazones studied were isolated and characterized by elemental and thermogravimetric analyses, magnetic susceptibility measurements (in the case of Cu(II) and Ni(II)) and IR spectrometry.     

Cumulative Author Index

Abstract

Bread represents an important source of trace elements in the human diet. This study is focused on home prepared bread in the Czech Republic. The amounts of Cu, Mo, Mn, Ni and Zn (total and soluble in Tris-HCl buffer, pH 7.5), Cd, Co, Fe, Pb and Tl (total only) as well as Hg (total and soluble in mercaptoethanol-HCl mixture) in raw materials and baked bread were determined using ICP-MS. Moreover, the speciation of elements was investigated using HPLC/ICP-MS. Isolated peptide ligands of the trace elements were analysed for amino acids and characterised by MALDI-MS. The concentrations of all elements were in accordance with Czech legislation. The solubility of the Ni species was not affected by the baking process, whereas the solubilities of Mo, Mn and Zn species decreased. Soluble mercury was found only in the inorganic form. The soluble species of Cu, Mo, Mn, Ni and Zn were found in two fractions with the apparent molecular weights of 1–2 kDa and 4–5 kDa. Ligands of trace metals isolated from these fractions contained appreciable amounts of Asx, Glx, Gly, Ser and Cys. No phytochelatin-like peptides were found in the MALDI-MS spectra of isolated ligands,. Using MALDI-MS/MS, the partial amino-acids sequences of peptide ligands were obtained, and the linkages of peptides and saccharides confirmed. The MS analysis of the trypsin digest of the medium molecular weight fraction revealed several proteins rich in cysteine (e.g., barwin and amylase inhibitors).     

Mobility and Translocation of Heavy Metals from Mine Tailings in Three Plant Species after Amendment with Compost and Biosurfactant

An experiment was performed to determine the effects of mine tailings alone mixed with compost or with compost plus crude biosurfactant on the accumulation of heavy metals (Pb, Zn, Cu, Cr, Cd, and Ni) in Acacia retinodes, Nicotiana glauca, and Echinochloa polystachya. The plants were grown in soil, mine tailings, and mine tailings containing compost over a period of seven and five months for shrubs or grass, respectively. The plants Acacia retinodes and Nicotiana glauca grown in mine tailings containing compost showed increases in dry biomass (from 62 to 79%) compared with plants in only tailings. Heavy metals accumulated in the roots and leaves showed high translocation rates of Cr in N. glauca, Cd in A. retinodes, and Ni in E. polystachya. Concentrations of heavy metals in the three plants irrigated with crude biosurfactant were not significantly different from those irrigated with water. Zn and Cd fractions within mine tailings containing compost were bound to carbonate, Pb was bound to residues, and Cu was bound to Fe-oxides. Cd had the highest mobility factor followed in order by Zn, Pb, and Cu. The elevated concentrations of Pb in roots and the low translocation rate for N. glauca and A. retinodes indicate that they are suitable for phytostabilizing Pb and Zn.