Metal Concentrations In Roots Research Articles

Seasonal variations of some heavy metals in common reed (Phragmites australis (Cav.) Trin. Ex. Steudel) and narrow-leaved cattail (Typha angustifolia L.) in Eğirdir Lake (Turkey) and the possibility of using for phytoremediation of these macrophytes.

This study which was carried out between July 2019 and April 2020 aimed to determine the seasonal changes of heavy metals (Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, and Zn) in plant organs of Phragmites australis and Typha angustifolia grown in Eğirdir Lake and to research the usability of the these plants for phytoremediation with the calculation of bioaccumulation factor (BF). Plant samples were brought to the laboratory, and then washed, cleaned with distilled water, dried in an oven at 70°C and acidified with 10ml HNO3. The samples were heated at 120°C on a hot plate until completely mineralized. After mineralization, heavy metal concentrations were determined by using ICP-AES (Vista model). Only Mo was the highest in leaf, while other metals were highest in root in P. australis. In T. angustifolia, Mn and Mo were highest in the leaf, the accumulation of other metals was observed to be higher in the plant's roots than the other organs. It was discovered that the metal concentrations in root, in stem, and in leaf for both macrophytes generally increased in summer and decreased in root in autumn and winter and in stem and in leaf in spring for P. australis and in all organs in spring for T. angustifolia. Bioaccumulation factor (BF) values were calculated to determine the phytoremediation potential of P. australis and T. angustifolia. Both macrophytes are not excluder for all metals. Plants revealed potential for phytoremediation for the removal of heavy metals especially Mo and Zn. As a result of our study, it was determined that both macrophytes had accumulation abilities especially for Mo and Zn. It should be taken into consideration that these macrophytes can be used for improving the current situation of Eğirdir Lake due to their advantages such as being economical and not causing any harm to the environment.

Effects of biochar, zeolite and mycorrhiza inoculation on soil properties, heavy metal availability and cowpea growth in a multi-contaminated soil

Heavy metal pollution of agricultural soil has become a major serious concern. The development of suitable control and remediation strategies for heavy metal contaminated soil has become critical. The outdoor pot experiment was conducted to investigate the effect of biochar, zeolite, and mycorrhiza on the bioavailability reduction of heavy metals and its subsequent effects on soil properties and bioaccumulation in plants as well as the growth of cowpea grown in highly polluted soil. Zeolite, biochar, mycorrhiza, zeolite with mycorrhiza, biochar with mycorrhiza, and soil without any modifications were the six treatments used. The experiment was conducted with a completely randomized design and four replications. The results indicated that the combination of biochar with mycorrhiza had the highest values of root and shoot dry weight and the lowest heavy metal concentrations in root and shoot as well as bioconcentration and translocation factors for all heavy metals. The highest significant reductions in the availability of heavy metals over the control were found with biochar with mycorrhiza, which were 59.1%, 44.3%, 38.0%, 69.7%, 77.8%, 77.2% and 73.6% for Cd, Co, Cr, Cu, Ni, Pb and Zn, respectively. The application of biochar and zeolite either alone or in combination with mycorrhiza increased significantly soil pH and EC compared to mycorrhiza treatment and untreated soil. It can be concluded that the combination of biochar and mycorrhizal inoculation has great potential as a cost-effective and environmentally technique for enhancing heavy metal immobilization, lowering heavy metal availability and plant uptake, and improving cowpea plant growth.

Maden Sahasından Ağır Metallerin (Cd, Zn, Pb) Ayçiçeği (Helianthus annuus) Bitkisiyle Fitoekstraksiyonu

Aim of study: The aim of this study was to determine the phytoremediation capacity of sunflower (Helianthus annuus L.), which can also be used as a bioenergy plant, in soils contaminated with copper (Cu), zinc (Zn) and lead (Pb) from the waste dumping sites during the mining operations. Area of study: Phytoremediation study was carried out in Artvin Coruh University Research greenhouse environment. Material and Methods: Plants were grown by mixing clean and contaminated soil at the rates of 0%, 50% and 100%. Bioaccumulation (BAF) and translocation (TF) factors were calculated by measuring heavy metal concentrations in soil and plant samples. The bioaccumulation factor is calculated by dividing the metal concentration in the shoots with the metal concentration in the soil. The translocation factor expresses the ratio of the metal concentration in the plant green parts to the root metal concentration. Main results: The sunflower plant has accumulated the highest Zn in the shoots, while Cu and Pb have accumulated the highest in the roots. The mean BAF values of the plants were determined as 0.72 for Zn, 0.5 for Pb and 0.28 for Cu, while the mean TF values were determined as 1.25 for Zn, 0.97 for Pb and 0.52 for Cu. Highlights: The findings show that the sunflower plant can be used in the phytostabilization of Cu metal and in the phytoextraction of Zn and Pb metal to reclaim heavy metal contaminated soils.

Phytoremediation Potential of Native Hyperaccumulator Plants Growing on Heavy Metal-Contaminated Soil of Khatunabad Copper Smelter and Refinery, Iran

The characterization of prospective plants is one of the critical issues in the efficiency and success of the phytoremediation process. Due to adaption and tolerance to different environmental stresses, native plant species have priority in this method. This study examined fifty plants of five species, namely Launaea acanthodes, Artemisia sp., Cousinia congesta, Peganum harmala, and Stipa sp., growing near a smelter and refinery in Iran to identify potential species for phytoextraction and phytostabilization. Therefore, Pb, Ni, Mn, Mo, S, and Cu concentrations in sampled plants and soils were analyzed. Three different pollution indices, namely metal accumulation index (MAI), translocation factor (TF), and bioconcentration factor (BCF) were used for evaluating the metal concentrations in roots and shoots of each plant species. The results indicated that Artemisia sp., with values of 3.21, 1.09, and 1.14 for MAI, BCF, and TF, respectively, is appropriate for phytoextraction in the study area. Plants such as Launaea acanthodes and Cousinia congesta with high BCF and low TF values showed the potential for phytostabilization. Investigating the indices for different elements demonstrated that Launaea acanthodes had a BCF value greater than 1 and a TF value less than 1; therefore, this plant could be used in the phytoremediation of arsenic through the phytostabilization technique. Furthermore, copper has very low bioavailability in these plant species. In addition, these native plant species were highly capable of accumulating sulfur from the soil because the BCF and TF indices for all inspected species were higher than 1; for Launaea acanthodes, the relevant TF value was about 10. The proposed native plant could be applied in practical applications of phytoremediation for soil remediation of contaminated sites around the metal factories and mines in southeastern Iran.

Dodonaea viscosa (Sapindaceae) as a phytoremediator for soils contaminated by heavy metals in abandoned mines.

Dodonaea viscosa (L.) Jacq. is a plant with a wide distribution that expands throughout almost all Mexican territory and is used in traditional medicine to treat many ailments. This species has been found associated with polluted areas, including mine tailings. Huautla, Morelos, Mexico, was a metallurgic district where mining activities generated 780,000 tons of waste rich in metals, deposited at 500m from the town without any treatment; this situation has been related to different environmental threats and human health risks. The study was carried out for 18months on seedlings developed under greenhouse conditions in two treatments: control substrate and mine tailings substrate. The concentration of six metals (Cd, Cr, Cu, Fe, Pb, and Zn) was measured through atomic absorption spectrophotometry in plant tissues, roots, and leaves. Effects of metal exposure were analyzed by size, micro-morphological character changes, and genetic damage in foliar tissue using the comet assay. The results showed significantly higher metal concentrations in the roots and leaves of individuals growing on the mine tailing substrate in comparison to the same plants tissues growing on control substrate. Positive and significant relationships between exposure time and metal concentration in roots and leaves, and between metal bioaccumulation in leaves and genetic damage were registered. Four out of six micro-morphological and size characters evaluated decreased significantly in exposed plants, except for stomatic index and root biomass. The most important metals in terms of the number of significantly affected micro-morphological and size characters showed the next pattern: Fe > Cd = Cr = Pb > Cu > Zn. D. viscosa is an efficient accumulator of Cu, Cd, Fe, Pb, and Zn in its root and leaf tissues. Overall, metal translocation factors in exposed D. viscosa plants showed the following pattern: Zn > Cu > Cd. We conclude that D. viscosa has the potential to phytoextract (Zn, Cu, and Cd), and phytostabilize (Cu, Cd, Fe, Pb, and Zn) metals from polluted soils, and along with its abundance, natural establishment in mine tailings, high levels of metal translocation, and bioconcentration factors, without affecting plant development, it can be an ideal candidate for phytoremediation of metal polluted soils.

The genetic diversity of Asplenium viride (Aspleniaceae) fern colonizing heavy metal-polluted sites

Asplenium viride is a diploid species, belonging to the largest genus of the cosmopolitan fern family Aspleniaceae and occurring on various types of alkaline rocks. It is known to colonize sites with high concentrations of heavy metals, exhibiting changes in frond morphology. A. viride can sometimes form new substrate-dependent ecotypes that can be morphologically and genetically different from parental populations. This study aimed to evaluate the morphological and genetic diversity of A. viride, and test for a potential correlation between variability and heavy metal concentration. Analysis of A. viride specimens from one metalliferous and five non-metalliferous sites showed elevated concentrations of heavy metals in roots of metalliferous plants. The concentrations were higher in roots than in aboveground organs, especially in the case of Cd and Pb, suggesting an excluder strategy for these metals. Both metalliferous and non-metaliferous sites were populated by plants with similar ploidy levels. The overall genetic diversity was low (HT = 0.25) and concentrated between populations (GST = 0.62). The obtained 2C DNA content ranged from 8.67 pg/2C to 8.69 pg/2C. STRUCTURE analysis revealed two groups among the studied populations which did not correlate with heavy metal concentrations and were not significantly supported by AMOVA. This suggests that factors influencing genetic diversity of A. viride are a consequence of intragametophytic selfing caused by patchy habitats and subsequent founder effects, resulting from long-distance colonization by single spores. The species has a potential to colonize heavy metal polluted sites; however, it does not seem to form genetically distinct ecotypes at those sites.

Lead-Tolerant Bacillus Strains Promote Growth and Antioxidant Activities of Spinach (Spinacia oleracea) Treated with Sewage Water

Irrigation with sewage-contaminated water poses a serious threat to food security, particularly in developing countries. Heavy metal tolerant bacteria are sustainable alternatives for the removal of wastewater contaminants. In the present study, four lead (Pb)-tolerant strains viz. Bacillus megaterium (N8), Bacillus safensis (N11), Bacillus sp. (N18), and Bacillus megaterium (N29) were inoculated in spinach and grown in sewage water treated earthen pots separately and in combination with canal water. Results showed that Pb-tolerant strains significantly improved plant growth and antioxidant activities in spinach and reduces metal concentration in roots and leaves of spinach plants irrigated with treated wastewater. Strain Bacillus sp. (N18) followed by B. safensis (N11) caused the maximum increase in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, and leaf area compared to the uninoculated control of sewage water treated plants. These strains also improved antioxidant enzymatic activity including catalase, guaiacol peroxidase dismutase, superoxide dismutase, and peroxidases activities compared to the uninoculated control under sewage water conditions. Strain Bacillus sp. (N18) followed by B. safensis (N11) showed the highest reduction in nickel, cadmium, chromium, and Pb contents in roots and leaves of spinach compared to the uninoculated control plants treated with the sewage water. Such potential Pb-tolerant Bacillus strains could be recommended for the growth promotion of spinach after extensive evaluation under field conditions contaminated with wastewater.

Cr, Ni, and Zn removal from landfill leachate using vertical flow wetlands planted with Typha domingensis and Canna indica

Chromium (Cr), Nickel (Ni), and zinc (Zn) removal from landfill leachate using mesocosm-scale vertical flow wetlands, the effect of recirculation, and the ability of macrophytes to retain metals were evaluated. Wetlands were filled with coarse sand and light expanded clay aggregates and planted with Typha domingensis or Canna indica. Wetlands were operated using intermittent loading, with and without recirculation. Raw leachate was diluted and spiked with metals to reach the following concentrations: 0.2 mg L−1 Cr , 0.2 mg L−1 Ni, and0.2 mg L−1 Zn and 1.0 mg L−1 Cr, 1.0 mg L−1 Ni, and 1.0 mg L−1 Zn. Wetlands planted with T. domingensis presented higher metal removal than those planted with C. indica. Recirculation enhanced metal removal efficiencies significantly, being for T. domingensis/C. indica: 60/54, 49/47, 61/47% for Cr, Ni, and Zn at 0.2 mg L−1, and 80/71, 76/62, 73/59% for Cr, Ni, and Zn at 1.0 mg L−1, respectively. Metals were efficiently retained by macrophytes. Plant biomass and metal concentrations in roots were significantly higher than in shoots. Scanning electron microscopy and X-ray microanalysis showed that metals were absorbed by internal root tissues. A hybrid wetland planted with T. domingensis may be implemented to improve not only metal but also chemical oxygen demand and total nitrogen removals.

Cyperus rotundus: a safe forage or hyper phytostabilizer species in copper contaminated soils

This study was carried out to evaluate Cu uptake, mobility, and accumulation in Cyperus rotundus and define the physiological strategy it employs under copper stress conditions. The experiment was performed at concentration levels from 12, 100, 150, 200, 250, and 300 mg Cu/kg in pod soil. The metal concentrations in roots, tubers, and root organs and the translocation factor (TF), total soluble sugars (TSS), and biomass production were evaluated. The results showed that the changes in TF and Cu concentrations had good fitness (p value < 0.01; R 2 > 0.87) with the quadratic models. These models have indicated C. rotundus has limited Cu translocation from the roots to the shoots (0.009 < TF < 0.05). The results also showed that TSS significantly (p value < 0.05) increased under Cu stress and changes in both the shoot and tuber tissues had good fitness with the quadratic model (R 2 > 0.98). In summary, C. rotundus is a hyper tolerant plant with a high ability to take up Cu from the soil, accumulate it in its underground tissues and prevent Cu translocate in above ground tissues. Therefore C. rotundus can be considered as a hyper phytostabilizer with the ability to hold Cu concentration in its shoot at a lower level than the maximum allowable concentrations in animal food and so can be recommend as safe forage in the copper contaminated environment. Novelty statement This paper reported for the first that Cyperus rotundus can be hyper Phytostabilizer if tubers and roots are considered as an unharvestable part. Cyperus rotundus can be suggested as a safe palatable plant due to the following three indices: (1) the maximum Cu concentration observed in the shoots is less than the maximum authorized concentration (MAC) in animal food, (2) the Translocation Factor of Cu (TF < 0.05) is very low, and (3) the physiological strategy of “excluders sensu Baker” used for copper phytostabilizing prevent more translocation and accumulation of Cu under more sever contaminated conditions, so this species could be used for grazing and forage production in copper contaminated environments. Safety forage assessment under a metal-contaminated environment using the three main indices described above is a novel idea.

Health risk assessment of heavy metals (Cu, Zn, and Mn) in wild oat grown in soils amended with sediment dredged from the Joumine Dam in Bizerte, Tunisia

The Joumine Dam located in northern Tunisia has lost more than 20% of its initial storage capacity due to sedimentation, meaning that sediment management is necessary. The sediments at the reservoir bottom act as a sink for nutrients and chemicals originating from the upper agricultural lands and take the form of suspended particles. We proposed that the dredged sediments could be used to amend arid to semiarid soils, as this would partially cover the financial burden of dredging works and reduce the volume of these deposits. However, to check the feasibility of using the sediments as a fertilizer, it was necessary to assess the potential health risks from contaminants in the sediments. Therefore, the present study aimed to evaluate the human health risk (i.e., the hazard quotient, HQ) from heavy metals consumed due to the ingestion of Bromus ramosus (wild oat) grown in soil amended with the Joumine Dam sediments. Plant growth was monitored in macrocosm (amendment rate of 1.17%) and microcosm (amendment rate ≤ 10%) bioassays to elucidate the metal concentrations in roots, stems, leaves, and seeds. Zn, Cu, and Mn concentrations were analyzed in the plants grown in the macrocosm experiments, while the follow-up was only performed for Zn in the plants grown in the microcosm experiments. The human exposure to soil pollutants (HESP) evaluation model was adopted to evaluate the health risk (HQ) to humans through direct and indirect oral exposure to heavy metals in wild oat. At the macrocosm scale, Cu was found to be the main source of risk (HQ = 1.86) to children. At the microcosm scale, utilization of the sediment reduced the mobility and bioavailability of copper in the soil, thus decreasing the potential health risk from this metal.Graphic abstract

Differential Growth and Metal Accumulation Response of Brachiaria Mutica and Leptochloa Fusca on Cadmium and Lead Contaminated Soil

ABSTRACT This work aims to assess growth, physiology, and metal uptake response of Brachiaria mutica and Leptochloa fusca under different contamination levels of Cd (10 and 50 mg kg−1) and Pb (50 and 250 mg kg−1) stress. Results of pot trial showed increasing metal concentration affected B. mutica more as compared to L. fusca. In B. mutica metal stress substantially reduced shoot dry biomass, root dry biomass, total chlorophylls, and carotenoids contents by 89%, 85%, 65%, and 61%, respectively, while enhanced the SOD activity up to 62 U min−1 g−1 FW. L. fusca showed better growth, chlorophylls and carotenoid contents, SOD activity (up to 79 U min−1 g−1 FW), shoot metal uptake potential (Cd 110 µg pot−1, Pb 91.57 µg pot−1), and root metal concentration (Cd 126 mg kg−1 dm, Pb 117 mg kg−1 dm) compared to B. mutica under Pb and Cd stress. While both grass species showed metal translocation factor less than unity under all levels of metal stress. Keeping in view the above results, it is concluded that L. fusca having better growth and physiology with TF < 1 could be used for phytostabilization of Pb and Cd to reclaim the soil having moderate to lower levels of contamination.

Effect of zeolite on absorption and distribution of heavy metal concentrations in roots and shoots of wheat under soil contaminated with weapons

War is one of the causes of agricultural lands pollution. One of the problems of this kind is pollution of heavy metals caused by the use of various types of weapons. These elements have entered the plant's life cycle and leads to endangering human health. The use of zeolite is a solution for this problem. The purpose of this study was to investigate the effect of natural zeolite on absorption and distribution of heavy metals in wheat. This experiment was conducted as a factorial based on completely randomized design with three replications. The treatments consisted of non-application of zeolite (zero) (control), 0.5, 1.5, and 2.5 percent of soil weight and two different types of soil include, contaminated and non-contaminated soil with war weapons. The results showed that the concentration of chromium, lead, and antimony increased in the roots and shoots in contaminated soil, significantly. The values of these elements were higher in roots as compared to shoots. The application of zeolite contributes significantly to the stabilization of heavy elements in contaminated soils and reduces their concentration in the shoots and roots and increases the food safety and food security which could be considered by researchers and farmers.

Phosphate treatment alleviated acute phytotoxicity of heavy metals in sulfidic Pb-Zn mine tailings

Phytostabilization of sulfidic PbZn tailing landscapes may be one of interim options of tailings management, but which is limited by acute phytotoxicity of heavy metals in the tailings. The present study aimed to investigate the effectiveness of soluble phosphate (i.e., K2HPO4) in immobilizing soluble Pb, Cd and Zn and lowering their acute phytotoxicity. The addition of soluble phosphate improved the growth of native plants Acacia chisholmii and survival rate of A. ligulata, where the latter exhibited 100% survival rate. This was in contrast to effects of conventional organic amendment in the tailings on metal solubility (e.g., elevated metal levels in porewater) and plant survival (e.g., only 42%). Organic amendment with mulch did not lower the levels of water-soluble Cd, Pb and Zn and their concentrations in plant tissues after 56 days of plant growth in the treatment. In contrast, the tailings amended with K2HPO4 significantly decreased metal concentrations in the porewater and plant tissues by about 80–92% and 56–88%, respectively. The metal immobilization by phosphate was due to the formation of insoluble or sparingly soluble metal (Pb, Cd and Zn)-phosphate minerals in the tailings with circumneutral pH conditions, as revealed by using X-ray diffraction and scanning electron microanalyses. The reduced metal concentrations in roots and shoots of Acacia species after direct root contact with the K2HPO4 amended tailings suggested that metals (i.e., Pb, Cd and Zn) were effectively immobilized by the phosphate treatment of the tailings. These findings indicate that addition of high dosage of soluble phosphate may provide a low cost option to treat sulfidic PbZn tailings for rapid phytostabilization of the tailings surface, as an interim option to manage environmental risks of sulfidic PbZn tailings.

Vermicompost utilization: A way to food security in rural area

The increase in agricultural production as well as its nutritional quality at a cost bearable by producers is today a challenge in rural areas. Vermicompost is a low-cost organic amendment known for its effectiveness on agricultural productivity increase but little is diffused about its efficacy on nutritional quality. This study aimed to evaluate the benefits of vermicompost from cattle dung on Lagenaria siceraria yield and its edible parts content in mineral and in heavy metal compared to raw dung. The study was carried out in the region of Mankono the biggest area for L. siceraria production in Côte d’Ivoire during three cycle seasons. The experiment consisted of three treatments arranged in a complete randomized block design with four replicates. The agronomic parameters as yield, number of leaves and flowers per plant were evaluated. Also, mineral nutrients and heavy metal concentrations in roots, leaves and seeds were measured. Results showed that yield, number of leaves and flowers per plant were higher with the vermicompost than with the cattle manure and the control. The yield obtained with the vermicompost was 2.5 times and 20 times higher respectively than that with the cattle manure and the control. Mineral concentrations in roots, leaves and seeds were the highest with the vermicompost when heavy metal contents were the lowest. The present study indicates that vermicompost utilization improves the yield and the nutritional quality of the edible parts of L. siceraria and hence could be recommended to producers for increasing productivity with keeping the health and safety of human.

Effects of the interactions between nickel and other trace metals on their accumulation in the hyperaccumulator Noccaea caerulescens

Nickel hyperaccumulators are a group of particular plant species which possess high efficient Ni uptake transport systems in their roots, the mechanisms of which however are far from being understood. Study on the interactions between nickel and other trace metals during root absorption process can provide insights into the Ni uptake patterns. Therefore, this work used model hyperaccumulator species Noccaea caerulescens to comprehensively assess the interaction between Ni and other trace metals (Zn, Fe, Mn, Cu and Co) during the root uptake process. Plants were grown in nutrient solutions containing different concentrations of Ni, Zn, Fe and Co, and the metal concentrations in roots and shoots were determined. Furthermore, the gene expression levels of Zn and Fe transporters were determined by quantitative real-time reverse transcriptase PCR. Results showed that Ni uptake could be severely suppressed by the presence of Zn or Co, while greatly stimulated by Zn or Fe deficiency. Iron uptake could be also stimulated by Ni exposure. In addition, the expression levels of the Zn transporter ZIP10 and the Fe transporter IRT1 were increased after Ni exposure. It could be concluded that the great competition between Ni and the non-essential element Co indicates that Ni uptake is mainly controlled by non-specific transporters. Nickel may be mainly taken up via Zn transporters, while Fe transporters also play a role for Ni absorption.

Heavy metal induced oxidative damage and root morphology alterations of maize (Zea mays L.) plants and stress mitigation by metal tolerant nitrogen fixing Azotobacter chroococcum

Heavy metals are one of the major abiotic stresses that adversely affect the quantity and nutritive value of maize. Microbial management involving the use of plant growth promoting rhizobacteria (PGPR) is a promising inexpensive strategy for metal clean up from polluted soils. Considering these, metal tolerant plant growth promoting nitrogen fixing rhizobacterial strain CAZ3 identified by 16SrRNA gene sequence analysis as Azotobacter chroococcum was recovered from metal polluted chilli rhizosphere. When exposed to varying levels of metals, A. chroococcum survived up to 1400 and 2000 µg mL−1 of Cu and Pb, respectively and expressed numerous plant growth promoting activities even under metal stress. Strain CAZ3 secreted 65.5 and 60.8 µg mL−1 IAA at 400 µg mL−1 each of Cu and Pb, respectively and produced siderophores, ammonia and ACC deaminase under metal pressure. The melanin extracted from A. chroococcum revealed metal chelating ability under EDX. Following application, strain CAZ3 enhanced growth and yield of maize grown both in the presence of Cu and Pb. The dry biomass of roots of inoculated plants grown with 2007 mg Cu kg−1 and 585 mg Pb kg−1 was increased by 28% and 20%, respectively. At 585 mg Pb kg−1, the bioinoculant also increased the kernel attributes. At 2007 mg Cu kg−1 strain CAZ3 enhanced the number, yield and protein of kernels by 10%, 45% and 6%, respectively. Interestingly, strain CAZ3 significantly reduced the levels of proline, malondialdehyde and antioxidant enzymes in foliage. The roots of inoculated plants accumulated greatest amounts of metals compared to other organs. In kernels, the concentration of Pb was more as compared to Cu. The metal concentrations in roots, shoots and kernels, however, declined following CAZ3 inoculation. Copper and lead had substantial distortive impact on root and leaf morphology while cell death were visible under CLSM and SEM. Conclusively, A. chroococcum CAZ3 could be a most suitable and promising option to increase maize production in metal polluted soils despite the soils being contaminated with heavy metals.

Effects of open dumping of MSW on metal contamination of soil, plants, and earthworms in Ranchi, Jharkhand, India.

Influence of open dumping of municipal solid wastes (MSW) on metal contamination of soil, plants, and earthworms in Ranchi, Jharkhand, India, was studied over 6-month period. Dumpsite in the study area exists in two sections, old section where waste dumping has stopped and new section where wastes are currently disposed. Soil around dumpsite had high concentration of Co, Cr, Cu, Pb, and Zn than that at control site. Geoaccumulation index indicated uncontaminated to moderate level of soil contamination at old dumpsite and soil at new dumpsite was found to be uncontaminated. Parthenium hysterophorus, Lantana camara, and Calotropis procera were the main plants found in patchy distribution around dumpsite. Plants exhibited almost similar levels of metal concentration in roots and shoots. P. hysterophorus and L. camara showed high bioaccumulation capacity and low translocation capacity. C. procera showed moderate bioaccumulation capacity and high translocation capacity as the concentration of metals was higher in the shoot. P. hysterophorus and L. camara due to higher bioaccumulation capacity and lower translocation capacity appear to be suitable for phytostabilization of metal-contaminated soil. Earthworms present at the dumpsite showed high concentration of Cr, Cu, Pb, and Zn with bioconcentration factor > 1. Results highlights that soil contamination due to metals is occurring at the dumpsite which is also leading to transfer of metals to plants and earthworms which can pose serious risk to environment and human health. The plants identified can be used for decontamination of metals from the dumpsite.

The influences of arbuscular mycorrhizal fungus on phytostabilization of lead/zinc tailings using four plant species

ABSTRACTA greenhouse experiment was conducted to investigate the effects of the arbuscular mycorrhizal fungus Funneliformis mosseae on three parameters: Pb, Zn, Cu and Cd accumulation, translocation and plant growth in perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinacea), showy stonecrop (Hylotelephium spectabile) and Purple Heart (Tradescantia pallida). The purpose of this work is to enhance site-specific phytostabilization of lead/zinc mine tailings using native plant species. The results showed that mycorrhizal fungi inoculation significantly increased plant biomass of F. arundinacea, H. spectabile and T. pallida. The Pb, Zn, Cu and Cd concentrations in roots were higher than those in shoots both with and without mycorrhizae, with the exception of the Zn concentration in H. spectabile. Mycorrhizae generally increased metal concentrations in roots and decreased metal concentrations in shoots of L. perenne and F. arundinacea. In addition, it was found that the majority of the bioconcentration and translocation factors were lower than 1 and mycorrhizal fungi inoculation further reduced these values. These results suggest that appropriate plant species inoculated with mycorrhiza might be a potential approach to revegetating mine tailing sites and that H. spectabile is an appropriate plant for phytostabilization of Pb/Zn tailings in northern China due to its higher biomass production and lower metal accumulation in shoots.

Bioavailability of adsorbed and coprecipitated Cu, Ni, Pb, and Cd on iron and iron/aluminum hydroxide to Phragmites australis.

The bioavailability of heavy metals strongly depends on their speciation in the environment. Adsorption (ADS) and coprecipitation (CPT) on amorphous metal hydroxides are important processes, controlling the fates of heavy metals in an aqueous environment. This work studied the bioavailability of Cu, Cd, Ni, and Pb adsorbed on and/or coprecipitated with amorphous iron and iron/aluminum mixed hydroxides to the wetland plant Phragmites australis. After a 13-day treatment, there was an apparent uptake of the heavy metals by the plant, and the amount of metal bioaccumulation was measurably different for different association forms (ADS vs. CPT). The bioaccumulation of Cd associated with Fe0.5Al0.5(OH)3 was greater than that with Fe(OH)3; the adsorbed metals were found to be more bioavailable than the coprecipitated forms for most of the treatments while the aging treatment significantly reduced the bioaccumulation of ADS metals. In the single metal treatment, root metal concentrations in the Fe(OH)3 ADS system followed the order Ni (68mgkg-1) > Cu (32mgkg-1) > Cd (28mgkg-1) > Pb (9mgkg-1), while the CPT system followed the order of Cu (30mgkg-1) > Ni (22mgkg-1) > Pb (9mgkg-1) > Cd (7mgkg-1). The order of metal accumulation in a combined metal treatment was similar to that for single metal treatments, but observed Ni concentration declines by 22 and 71% and Cu and Cd concentrations increase by 30 and 50% (for CPT and ADS treatments, respectively), while Pb concentrations increased by 30~50% in both of them. When treated with low-molecular-weight organic acids (LMWOAs), metal desorption, indicative of metal oxide bonding strength and metal bioavailability, was consistent with metal accumulation in the plant.

Distribution of Cd and Pb Accumulated in Medicinal Plant Roots and Their Cultivation Soils

In general, plant roots accumulate more heavy metals than the above ground organs such as leaf, stem, and fruit. This implies that root medicinal plants would be an issue with excessive heavy metal accumulation. Therefore, the current study was carried out to investigate the distribution of heavy metal (focused on Cd and Pb) concentrations in soils and medicinal plant roots grown in different region of Korea. Total 293 samples for each soil and plant were collected along the national wide. Soil pH, total and phytoavailable metal concentrations (1 M NH₄NO₃ extracted) in soils were determined and heavy metal concentrations in root of the medicinal plants were analyzed. Heavy metal concentrations of the soil samples studied were not exceeded standard limits legislated in ‘Soil Environmental Conservation Act’, except 2 samples for Cu. However, substantial amount of Cd was accumulated in medicinal plant roots with 29% samples exceeding the standard limit legislated in ‘Pharmaceutical Affairs Act’ while all plant samples were lower than the standard limit value for Pb. Also the current study demonstrated that cadmium concentrations in the roots were governed by the phytoavailable Cd in soils, which decreased as soil pH increased. From this result, application of heavy metal immobilization technique using a pH change-induced immobilizing agents can be suggested for safer root medicinal plant production.