Agaricus bisporus compost improves the potential of Salix purpurea × viminalis hybrid for copper accumulation

The aim of the study was to determine the ability of spent mushroom compost (SMC) from the production of Agaricus bisporus (A. bisporus) to stimulate the growth and efficiency of copper (Cu) accumulation by Salix purpurea × viminalis hybrid. Roots, shoots and leaves were analysed in terms of total Cu content and selected biometric parameters. Due to the absence of information regarding the physiological response of the studied plant, low molecular weight organic acids (LMWOAs), phenolic compounds and salicylic acid (SA) contents were investigated. The obtained results clearly demonstrate the effectiveness (usefulness) of SMC in promoting the growth and stimulation of Cu accumulation by the studied Salix taxon. The highest Cu content in roots and shoots was found at the 10% SMC addition (507±22 and 380±11 mg kg^?1 DW, respectively), while there was a reduction of the content in leaves and young shoots (109±8 and 124±7 mg kg^?1 DW, respectively). In terms of physiological response, lowered secretion of LMWOAs, biosynthesis of phenolic compounds and SA, as well as accumulation of soluble sugars in Salix leaves was observed with SMC addition. Simultaneously, an elevation of the total phenolic content in leaves of plants cultivated with SMC was observed, considered as antioxidant biomolecules.     

Characterization of Pb and Cd contamination in the feces and feathers of rook (Corvus frugilegus) and the scalp hair of residents in Qiqihar,northeastern China

The concentrations of Pb and Cd, and trace elements (Cu and Zn) in the urban topsoil, rook (Corvus frugilegus) feces and feathers and human scalp hair were analyzed to examine the potential ecological risk posed by Pb and Cd on local residents of Qiqihar City, northeastern China. Results revealed that the Cd concentrations in the topsoil were ranged from 0.14 to 3.55 mg kg^?1 dry weight (dw). The maximal geoaccumulation indices [a value from logarithmic (a measured metal content/1.5 × background content of the metal in this region), introduced by Muller] of Cd exceeded 3.5, which suggested that this region was seriously contaminated by Cd. The corresponding average detectable concentrations in C. frugilegus feathers and feces were 1.38 and 3.97 mg kg^?1 dw for Pb and 1.04 and 0.69 mg kg^?1 dw for Cd. High Pb and Cd concentrations, respectively, ranging from 7.46 to 24.9 mg kg^?1 dw and from 0.35 to 0.92 mg kg^?1 dw were also detected in the human scalp hair samples. These high Pb and Cd concentrations in C. frugilegus and local people were possibly associated with local industrial wastes and vehicle exhausts. The external tissues (feces and feather) of the rook species can be considered as an indicator of potential Cd toxic risk in this species; however, the human scalp hair is not a reliable biomarker for risk of Pb and Cd in the human being. Effective measures should be established to reduce the inputs of Pb and Cd into the urban environment and to protect the health of local people.     

Biomass growth variation and phytoextraction potential of four Salix varieties grown in contaminated soil amended with lime and wood ash

Abstract

In a greenhouse experiment, plant growth and copper (Cu) and zinc (Zn) uptake by four Salix cultivars grown in Cu and Zn contaminated soils collected from a mining area in Finland were tested to assess their suitability for phytoextraction. The cultivars displayed tolerance to heavily contaminated soils throughout the experiment. After uptake, total mean Cu concentrations in the leaves, shoots and roots in all cultivars and treatments ranged from 163 to 474?mg kg^?1 and mean Zn concentrations ranged from 776 to 1823?mg kg^?1. Lime and wood ash addition increased dry biomass growth (25–43%), chlorophyll fluorescence (Fv/Fm) values (3–6%), the translocation factor (TF) (15–60% for Cu; 10–25% for Zn), the bio-concentration factor (BCF) (40–85% for Cu; 70–120% for Zn), and metal uptake (55–70% for Cu; 50–65% for Zn) compared to unamended treatment across all cultivars. The results revealed that Salix cultivars have the potential to take up and accumulate significant amounts of Cu and Zn. Cultivar Klara (Salix viminalis × S. schwerinii × S. dasyclados) was found to be the most effective cultivar for phytoextraction since it displayed greater dry biomass production, Fv/Fm, TF, BCF values and uptake percentage rates of Cu and Zn compared to the other three cultivars. This study indicates that further research is needed to clarify the wider phytoextraction capabilities of different Salix cultivars.     

The role of bacteria on heavy-metal extraction and uptake by plants growing on multi-metal-contaminated soils

Four bacterial isolates were examined for their ability to increase the availability of water soluble Cu, Cr, Pb and Zn in soils and for their effect on metals uptake by Zea mays and Sorghum bicolor. Random Amplified Polymorphic DNA (RAPD) analysis was used to show that the bacterial cultures were genetically diverse. Bacterial isolates S3, S28, S22 and S29 had 16S rRNA gene sequences that were most similar to Bacillus subtilis, Bacillus pumilus, Pseudomonas pseudoalcaligenes and Brevibacterium halotolerans based on 100% similarity in their 16S rDNA gene sequence, respectively. Filtrate liquid media that had supported B. pumilus and B. subtilis growth significantly increased Cr and Cu extraction from soil polluted with tannery effluent and from Cu-rich soil, respectively, compared to axenic media. The highest concentrations of Pb (0.2 g kg⁻¹), Zn (4 g kg⁻¹) and Cu (2 g kg⁻¹) were accumulated in shoots of Z. mays grown on Cu-rich soil inoculated with Br. halotolerans. The highest concentration of Cr (5 g kg⁻¹) was accumulated in S. bicolor roots grown in tannery-effluent-polluted soil inoculated with a mixed inoculum of bacterial strains. These results show that bacteria play an important role in increasing metal availability in soil, thus enhancing Cr, Pb, Zn and Cu accumulation by Z. mays and S. bicolor.     

Total Phenols,Flavonoids and Antioxidant Activity in <i>Annona muricata</i> and <i>Annona purpurea</i> Callus Culture

Callus cultures of Annona muricata and Annona purpurea were induced in Murashige and Skoog (MS) medium supplemented with different concentrations of 1-naphthylacetic acid (NAA), 6-benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D) utilized hypocotyls with explant. The highest percentage of callus formation was the treatment supplemented with 3 mg L^-1 NAA for A. muricata (100%) while for A. purpurea in lower percentage (75%). BA stimulated the formation of shoots in all the evaluated concentrations, being the concentration of 2 mg L^-1 the one that induced the greater formation of shoots for A. muricata (23 shoots/explant) and A. purpurea (28 shoots/explant). The content of total phenols, flavonoids and antioxidant activity was measured in the callus obtained from both species. The results showed that a higher content of total phenols was quantified in callus of A. purpurea (27.8 mg g^-1 dw) compared to A. muricata (23.2 mg g^-1 dw). The highest content of total flavonoids was observed in the callus of A. purpurea (8.0 μg g^-1 dw). Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydracil radical assay. The concentration required for 50% inhibition (IC50) of the 2,2-diphenyl-1-picrylhydracil radicals were 4.22 μg mL^-1 in methanolic extracts of callus of A. muricata, while in extracts of callus of A. purpurea was 2.86 μg mL^-1, in both cases was greater than that found for leaves. Callus culture of the species studied in this work represents an alternative for the production of natural antioxidants.     

The phytoprotective effects of arbuscular mycorrhizal fungi on Enterolobium contorstisiliquum (Vell.) Morong in soil containing coal-mine tailings

The purpose of this study was to evaluate the effects of arbuscular mycorrhizal fungi (AMF) on pacara earpod tree (Enterolobium contorstisiliquum) growth and phytoprotection in soil containing coal-mining waste. A greenhouse experiment was carried out with three inoculation treatment groups (non-inoculated, inoculated with Rhizophagus clarus, and inoculated with Acaulospora colombiana) in two substrates (0 or 30% tailings). After 90 days the seedlings were collected to quantify growth parameters, quality, mycorrhizal root colonization rate, and leaf content of chlorophylls and carotenoids. Macronutrients were quantified in the shoots; Cu, Zn, and Mn levels were measured in the shoots and roots; and glomalin content was measured in the rhizosphere. Colonization by A. colombiana (40%) promoted phytoprotection and better growth in seedlings planted in partial tailing substrate, due to the lower Cu (1.04 mg kg^?1) and Zn (13.4 mg kg^?1) levels in shoot dry mass and reduced translocation of these elements to the shoots. A. colombiana increased soil glomalin concentrations (2.98 mg kg^?1) and the accumulation of nutrients necessary for synthesizing chlorophylls and carotenoids in the leaves. Colonization by R. clarus (81%) produced no phytoprotective effects.     

METAL UPTAKE AND ALLOCATION IN TREES GROWN ON CONTAMINATED LAND: IMPLICATIONS FOR BIOMASS PRODUCTION

Phytostabilization aims to reduce environmental and health risks arising from contaminated soil. To be economically attractive, plants used for phytostabilization should produce valuable biomass. This study investigated the biomass production and metal allocation to foliage and wood of willow (Salix viminalis L.), poplar (Populus monviso), birch (Betula pendula), and oak (Quercus robur) on five different soils contaminated with trace elements (TE), with varying high concentrations of Cu, Zn, Cd, and Pb as well as an uncontaminated control soil. In the treatment soils, the biomass was reduced in all species except oak. There was a significant negative correlation between biomass and foliar Cd and Zn concentrations, reaching up to 15 mg Cd kg^?1 and 2000 mg Zn kg ^?1 in willow leaves. Lead was the only TE with higher wood than foliage concentrations. The highest Pb accumulation occurred in birch with up to 135 mg kg ^?1 in wood and 78 mg kg ^?1 in foliage. Birch could be suitable for phytostabilization of soils with high Cd and Zn but low Pb concentrations, while poplars and willows could be used to stabilise soils with high Cu and Pb and low Zn and Cd concentrations.     

Heavy metal pollution monitoring using the brown seaweed Padina durvillaei in the coastal zone of the Santa Rosalía mining region, Baja California Peninsula, Mexico

The coastal marine sediments near Santa Rosalía on the eastern coast of the Baja California Peninsula (Mexico) are heavily polluted by metals due to copper mining and smelting over the past century (up to 1984). The present study compares the accumulation of metals in the brown seaweed Padina durvillaei from the central segment of the coast of Santa Rosalía (polluted by Co, Cu, Mn and Zn) and from two segments north and south of the known “hot spot”. The seaweed samples were collected in May and August 2004 and June 2005 at 13 stations located along the Santa Rosalía mining region. Heavy metal concentrations were measured by instrumental neutron activation analysis (Co and Fe) directly in dried homogenized subsamples or by flame atomic absorption spectrophotometry (Cd, Cu, Mn, Ni, Pb and Zn) after complete strong acid digestion of sub-samples. The means and standard deviations of the concentrations in dry tissues of Padina durvillaei specimens for all the studied metals and stations lie in the following sequence: Cd (3.6 ± 1.6 mg kg⁻¹) < Co (6.5 ± 6.1 mg kg⁻¹) < Pb (7.8 ± 6.2) < Ni (9.96 ± 5.28 mg kg⁻¹) < Cu (53 ± 38 mg kg⁻¹) < Zn (63 ± 43 mg kg⁻¹) < Mn (295 ± 269 mg kg⁻¹) < Fe (2243 ± 2325 mg kg⁻¹). This increase of the average concentrations was statistically significant. Principal Component Analysis showed that Factor 1 (36.46%) displays high positive loadings for Co, Cu, Mn and Zn, reflecting the influence of local anthropogenic pollution on the seaweed composition, while Factor 2 (26.91%) is important for Co, Fe and Ni and probably corresponds to the adsorption or accumulation of terrigenous elements of the regional origin, while Factor 3, with a high positive loading for Pb and a high negative loading for Cd, is probably controlled by local and regional anthropogenic input of Pb and episodic supply of Cd by local upwellings. The results of ANOVA for each element do not show any significant differences between the average concentrations for Cd, Fe, Ni and Pb in the seaweed of the three segments, or between the central and southern segments for Cu, Mn and Zn. Cobalt contents in the seaweed from the northern and central segments are, however, significantly different from the southern segment. This indicates that element concentrations in Padina durvillaei generally do not follow the drastic increases and gradients of Cu, Co, Mn and Zn contents detected in surface sediments. The apparent contradiction could be explained by a low geochemical mobility of these metals in the polluted sediments, composed mainly of stable residues of smelter wastes, with very low content of organic matter usually driving diagenetic mobilization of some metals into interstitial waters and then to the overlying water.     

Metal residues in flesh of edible blue crab,Callinectes amnicola,from a tropical coastal lagoon: Health implications

Metals such as cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu) were estimated in the flesh of the edible blue crab Callinectes amnicola from selected areas of the Lagos Lagoon, Nigeria (i.e., Makoko, Iddo, Okababa, Ikoyi, and Ajah) for 18 months between March 2011 and August 2012. Estimated average daily intake (EADI) and target hazard quotient (THQ) were used to determine the risk implications for adult and child consumer populations. Range of Cd, Pb, Zn, and Cu across sites was 0.16–0.46, 1.48–3.17, 2.21–3.65, and 9.48–12.76 mg kg^?1 crab flesh wet weight, respectively. Lead concentrations in crab flesh from Makoko (3.16 ± 1.44 mg kg^?1) and Iddo (5.17 ± 1.26 mg kg^?1) exceeded the maximum accepted limits recommended by the Food and Agriculture Organization/World Health Organization for food fisheries. The EADI across sites for the adult consumer population exceeded the reference dose (RfD) recommended by the U.S. Environmental Protection Agency for most metals with magnitude of ≤7-fold while EADI of Pb among child consumer population across sites exceeded RfD by a maximum of 4.5-fold. THQs for adult population were >1 for all metals across all sites, and >1 for Pb and Cd for selected sites for the child consumer population. Findings from this study indicate higher health risks of metal toxicity to adult consumer populations, and risks of lead toxicity to child consumer populations around the Lagos Lagoon, Nigeria.     

PHYTOEXTRACTION OF METAL POLLUTED SOILS AROUND A Pb-Zn MINE BY CROP PLANTS

In order to assess their practical capability for the absorption and accumulation of Pb, Zn, and Cu, five common crop plants, i.e. maize (Zea mays), sunflower (Helianthus annuus), canola (Brassica napus), barley (Hordeum vulgare) and White lupine (Lupinus albus) were tested in pot experiments using six soil samples taken from mine tailings, pasture and arable soils around an old Pb-Zn mine in Spain. Metal concentration ranges of the soils were 76.2–785 mg kg^?1, 127–1652 mg kg^?1, and 12.4–82.6 mg kg^?1 for Zn, Pb, and Cu, respectively. With the exception of the highest polluted sample, soil total metal concentration did not influence significantly biomass yields of each crop for the different growth substrates. The order found for the total metal accumulation rate (TMAR) in the crops was Zn>>Pb > Cu, with maize reaching the highest metal concentrations. Pb root concentrations were markedly higher than those of shoots for all the crops, while Zn and Cu were translocated to shoots more efficiently. Concentrations of metals extracted by EDTA and BCR sequential extraction were well correlated, in general, with both root metal content and TMAR. CaCl₂-extracted Zn was well correlated with root concentrations, TMAR and, in some cases, with shoot contents. Our study showed that the test crops were not feasible to remediate the heavily or moderately contaminated soils studied here in order to achieve the total metal soil concentrations required by the current European laws.     

A novel <Emphasis Type="Italic">Trichoderma</Emphasis> fusant for enhancing nutritional value and defence activity in chickpea

In recent years, due to the rise in food consumption, much of the attention has been focused to increase the yield of the agricultural crops which resulted in compromised nutritional quality. Efforts have to be undertaken to enhance the nutritional attributes of legumes, cereals and staple food crops by increasing amino acids and mineral content. In the present study, we evaluated a protoplast fusant (H. lixii MTCC 5659) for its ability to enhance nutritional value and defence activity in chickpea. Essential amino acids; methionine (9.82 mg kg^?1 dw), cysteine (2.61 mg kg^?1 dw), glycine (11.34 mg kg^?1 dw), valine (9.26 mg kg^?1 dw), and non-essential amino acids; aspartic acid (39.19 mg kg^?1 dw) and serine (17.53 mg kg^?1 dw) were significantly higher in seeds of fusant inoculated chickpea. Fusant significantly improved accumulation of mineral nutrients i.e. Cu (157.73 mg kg^?1 dw), Co (0.06 mg kg^?1 dw), Ni (1.85 mg kg^?1 dw), Zn (157.73 mg kg^?1 dw) and S (16.29 mg kg^?1 dw) in seeds. Biocontrol and defence activities of chickpea increased from 20 to 35% in fusant inoculated plants suggesting its potential to ameliorate biotic stress. To the best of our knowledge, this is the first report of an increase in amino acids and mineral content of chickpea by fusant inoculation.     

Phytoextraction of Risk Elements by Willow and Poplar Trees

To characterize the phytoextraction efficiency of two clones of willow trees (Salix x smithiana Willd., Salix rubens) and two clones of poplar trees (Populus nigra x maximowiczii, Populus nigra Wolterson) were planted in contaminated soil (0.4–2.0 mg Cd.kg^?1, 78–313 mg Zn.kg^?1, 21.3–118 mg Cu.kg^?1). Field experiment was carried out in Czech Republic. The study investigated their ability to accumulate heavy metals (Cd, Zn, and Cu) in harvestable plant parts. The poplars produced higher amount of biomass than willows. Both Salix clones accumulated higher amount of Cd, Zn and Cu in their biomass (maximum 6.8 mg Cd.kg^?1, 909 mg Zn.kg^?1, and 17.7 mg Cu.kg^?1) compared to Populus clones (maximum 2.06 mg Cd.kg^?1, 463 mg Zn.kg^?1, and 11.8 mg Cu.kg^?1). There were no significant differences between clones of individual species. BCs for Cd and Zn were greater than 1 (the highest in willow leaves). BCs values of Cu were very low. These results indicate that Salix is more suitable plant for phytoextraction of Cd and Zn than Populus. The Cu phytoextraction potential of Salix and Populus trees was not confirmed in this experiment due to low soil availability of this element.     

A Counter-Current Acid Leaching Process for the Remediation of Contaminated Soils from a Small-Arms Shooting Range

The objective of this research was to use a counter-current leaching process (CCLP) with leachate treatment to develop a remediation process for contaminated soils at a small-arms shooting range (SASR). The soil contaminant concentrations were 245 mg Cu kg^?1, 3,368 mg Pb kg^?1, 73 mg Sb kg^?1, and 177 mg Zn kg^?1. The CCLP includes three acid leaching steps (1M H₂SO₄ + 4M NaCl, t = 1 h, T = 20°C, soil suspension = 100 g L^?1), followed by one water rinsing step (1 h). Seven counter-current remediation cycles were completed, and the average resulting metal removals were 93.2 ± 3.5% of Cu, 91.5 ± 5.7% of Pb, 82.2 ± 10.9% of Sb, and 30.0 ± 11.4% of Zn. The metal leaching performances decreased with the number of completed cycles. Soil treated with the CCLP with leachate treatment process met the USEPA threshold criteria of 5 mg Pb L^?1 in the TCLP leachate. The CCLP allows a decrease of the water use by 32.9 m³ t^?1 and the chemicals’ consumption by approximately 2,650 kg H₂SO₄, 6,014 kg NaCl, and 1,150 kg NaOH per ton of treated soil, in comparison to standard leaching processes. This corresponds to 78%, 69%, 83%, and 67% of reduction, respectively.     

Contrasting Effects of Farmyard Manure (FYM) and Compost for Remediation of Metal Contaminated Soil

We investigated effect of farm yard manure (FYM) and compost applied to metal contaminated soil at rate of 1% (FYM-1, compost-1), 2% (FYM-2, compost-2), and 3% (FYM-3, compost-3). FYM significantly (P < 0.001) increased dry weights of shoots and roots while compost increased root dry weight compared to control. Amendments significantly increased nickel (Ni) in shoots and roots of maize except compost applied at 1%. FYM-3 and -1 caused maximum Ni in shoots (11.42 mg kg^?1) and roots (80.92 mg kg^?1), respectively while compost-2 caused maximum Ni (14.08 mg kg^?1) and (163.87 mg kg^?1) in shoots and roots, respectively. Plants grown in pots amended with FYM-2 and compost-1 contained minimum Cu (30.12 and 30.11 mg kg^?1) in shoots, respectively. FYM-2 and compost-2 caused minimum zinc (Zn) (59.08 and 66.0 mg kg^?1) in maize shoots, respectively. FYM-2 caused minimum Mn in maize shoots while compost increased Mn in shoots and roots compared to control. FYM and compost increased the ammonium bicarbonate diethylene triamine penta acetic acid (AB-DTPA) extractable Ni and Mn in the soil and decreased Cu and Zn. Lower remediation factors for all metals with compost indicated that compost was effective to stabilize the metals in soil compared to FYM.     

Zn,Cd, S and trace metal bioaccumulation in willow (Salix spp.) cultivars grown hydroponically

Willows (Salix spp.) can be used to phytoremediate soils contaminated by Zn and Cd under certain conditions. In this study, the ability of 14 Salix cultivars to concentrate Cd, Zn and S in leaves was measured in hydroponic culture with 10 and 200 µM Cd and Zn, respectively, in the nutrient medium. The cultivars showed a wide range of biomass yields, tolerance to metals, and foliar concentrations of Zn and Cd, with some cultivars accumulating up to 1000 mg kg^?1 Zn, 70 mg kg^?1 Cd and 10,000 mg kg^?1 S with only mild phytotoxicity symptoms attributable to excess Zn. Cultivars with higher foliar Zn concentrations tended to have higher foliar Cd concentrations as well, and competition between Zn and Cd for uptake was observed. Exposure of Salix cultivars to Cd and Zn did not affect foliar concentrations of secondary metabolites such as polyphenols, but trace metal concentrations in leaves were significantly reduced (Fe and Cu) or increased (Mn) by exposure to excess Zn and Cd. Sulfur-XANES spectroscopy showed foliar S to be predominantly in highly oxidized (sulfate plus sulfonate) and reduced (thiol) forms, with oxidized S more prevalent in willows with the highest total S content.     

Strategies for lead distribution in organs of <Emphasis Type="Italic">Phragmites australis</Emphasis> (Cav.) Trin. ex Steud. (Common reed) subjected to Pb pollution in flood and drought environments

Heavy metal allocation in clonal organs, stems, leaves, and roots has not been systematically studied for rhizomatous perennial plants. Here, pot experiments have been designed to investigate lead (Pb) distribution in different organs of Phragmites australis (Cav.) Trin. ex Steud. Common reed subjected to 0–4500 mg Pb kg^?1 under both flood and drought conditions. In either water treatment, Pb concentrations in offspring shoots were lower than in parent shoots; however, the opposite response was observed for biomass allocation for which parent shoots protected offspring shoots. Lower allocation of Pb to leaves rather than stems in offspring shoots could be a protective strategy of leaves under flood conditions. Lower Pb allocation to rhizomes is better for rhizome growth. This further provides energy for the growth of buds and offspring shoots, because the rhizome biomass and the number of buds and offspring shoots were not significantly inhibited by Pb levels of?≤?3000 mg kg^?1 in the flooded environment. These Pb allocation strategies could enhance the resistance capacity of reeds to Pb contamination by stabilizing population propagation and productivity, especially at Pb levels of?≤?3000 mg kg^?1 under flood conditions.     

龙胜县丘陵山区土壤与罗汉果重金属含量及潜在生态危害评价——以宝赠村为例

桂林市龙胜县作为罗汉果的三大主产区之一,种植区土壤重金属含量及罗汉果质量影响到该区罗汉果产业的健康发展.为探索龙胜县丘陵山区典型贫困村罗汉果园的安全性,该文研究了宝赠村典型罗汉果园土壤及罗汉果果实中砷、铜、锌、铅、镉、铬、汞7种重金属含量,并采用Hankanson指数法分析了其潜在生态风险.结果表明:(1)龙胜丘陵山区...     

Diversity of low-molecular weight organic acids synthesized by <Emphasis Type="Italic">Salix</Emphasis> growing in soils characterized by different Cu,Pb and Zn concentrations

The aim of the study was to evaluate the biosynthesis and exudation of 10 low-molecular weight organic acids (LMWOAs) into the rhizosphere with a simultaneous analysis of the acid contents in the roots and leaves of 9 Salix taxa growing on two experimental areas, differing in their concentrations of copper (Cu), lead (Pb) and zinc (Zn) in the soil (Area 1—low, Area 2—high concentration). The obtained results reveal a significant difference in the phytoextraction of the tested Salix taxa for the analysed metals in both areas. The highest contents of Cu, Pb and Zn were observed for all Salix collected from Area 2, especially in S. × smithiana roots (116 ± 8.76, 87.84 ± 7.30 and 203.42 ± 14.62 mg kg^?1 DW, respectively). The results obtained in Area 2 also revealed acidification of the rhizosphere and a higher concentration of acids, mainly oxalic, malic, malonic, acetic and citric acids. Contents of oxalic, malic, acetic and citric acids increased in the roots of Salix taxa from Area 2, while in the leaves formic and succinic acids were also present. S. × smithiana was the taxon with the highest concentration of acids in the rhizosphere and roots (73.48 ± 6.77 and 49.79 ± 2.65 μM 100 g^?1 DW, respectively), while in leaves a higher content was observed for S. alba and S. viminalis ‘PR’ taxa (78.12 ± 3.95 and 71.12 ± 3.75 μM 100 g^?1 DW, respectively).     

Screening of metal uptake by plant colonizers growing on abandoned copper mine in Kapunda,South Australia

Systematic site survey for sample collection and analysis was conducted at a derelict copper (Cu) mine at Kapunda, South Australia. Cu concentrations in the soils at this former mine ranged from 65–10107 mg kg^?1. The pH and EC varied widely in the 3.9–8.4 and 152–7311 µS ranges, respectively. Nine plant species growing over the copper mine site were selected to screen for metal uptake to determine their suitability for phytoremediation. The Australian native tree species Eucalyptus camaldulensis indicated enrichment factor (EF) of 2.17, 1.89, and 1.30 for Cu, Zn, and Pb, respectively, suggesting that this species of tree can accumulate these metals to some degree. The stress-resistant exotic olive, Olea europaea exhibited EF of ≤ 0.01 for Cu, Cd, and Pb, and 0.29 for Zn, which is characteristic of an excluder plant. Acacia pycnantha, the Australian pioneer legume species with EF 0.03, 0.80, 0.32, and 0.01 for Cu, Zn, Cd, and Pb, respectively, emerged as another strong metal excluder and consequently as an ideal metal stabilizer.     

Metal accumulation and arbuscular mycorrhizal status in metallicolous and nonmetallicolous populations of <Emphasis Type="Italic">Pteris vittata</Emphasis> L. and <Emphasis Type="Italic">Sedum alfredii</Emphasis> Hance

Although Pteris vittata L. and Sedum alfredii Hance have been identified as an As hyperaccumulator and a Zn/Cd hyperaccumulator, respectively, for a few years, variations in metal accumulation among populations and their arbuscular mycorrhizal (AM) status have not been fully explored. Six populations of P. vittata and four populations of S. alfredii from southeast China were investigated. Up to 1,373 As, 680 Pb, 376 Zn, 4.8 Cd, 169 Cu mg kg⁻¹ in fronds of P. vittata and 358 As, 2,290 Pb, 23,403 Zn, 708 Cd, 342 Cu mg kg⁻¹ in shoots of S. alfredii were detected. Constitutive properties of As and Zn hyperaccumulation in metallicolous populations of P. vittata and S. alfredii, respectively, were confirmed. However, Cd hyperaccumulation in S. alfredii varied among populations. The two hyperaccumulators varied in efficiency in taking up other heavy metals. Different metal tolerance strategies adopted by the two hyperaccumulators varied among plant species and metal species. Low to moderate levels of AM colonization in P. vittata (4.2–12.8%) and S. alfredii (8.5–45.8%) were observed at uncontaminated and metal-contaminated sites. The relationship between metal concentrations and AM colonization in the two hyperacumulators was also examined. The abundance of AM fungal spores ranged from 16 to 190 spores per 25 g soil. Glomus microaggregatum, Glomus mosseae, Glomus brohultii and Glomus geosporum were the most common species associated with both P. vittata and S. alfredii. To our knowledge, this is the first report of AM fungal status in rhizosphere of P. vittata and S. alfredii.