Pb In Roots Research Articles

The Absorption and Distribution of Heavy Metals of Dominant Plant for Ecological Restoration of Stone Coal Mine

The exposed slopes formed by stone mining had caused serious problems of environmental pollution. The ecological restoration was a very effective measure to solve it. In this study, the Indigofera amblyantha Craib was the dominant species in the ecorestoration during the first two years of ecological restoration, which was based on analyzing the importance value (IV) and diversity indexes of plant species. Meanwhile, the ecorestoration process helps slow down the increase of the concentrations of some heavy metals in the substrate material; however, the changing trends of these metals were not uniform. The root and leaf were the main parts of heavy metal distribution, respectively, corresponding to Pb, Cr, As, Sb, and Ni in root and Cu, Mn, and V in leaf. It confirmed that Indigofera amblyantha Craib had an advantage ability to enrich and transfer Cd, Cu, and Mn obtained from their biological concentration factor (BCF) and biological transfer factor (BTF). The Sb, Cd, and V were the main factors affecting the IV by the redundancy analysis. These fine characters of Indigofera amblyantha Craib help explain it well adapted to the ecorestoration of stone coal mines. The current results are valuable to evaluate and extend the application in ecorestoration engineering of mining areas and other heavy metal-contaminated sites.

Immobilization of Pb and Cu by organic and inorganic amendments in contaminated soil

Soil contamination with heavy metals has become a global environmental-health concern. A series of greenhouse experiments were conducted to investigate the effects of rice straw, rice straw derived biochar (BC), multi-walled carbon nanotubes, and single superphosphate (SSP) on immobilization of Pb and Cu via sequential extraction of BCR, total characteristics leaching procedure (TCLP), and metals phytoavailability to rapeseed in Pb and Cu spiked soil. Moreover, the residual effect of applied soil amendments on growth and uptake of Pb and Cu in tomato was also investigated in the metals spiked soil. In results, the addition of BC to Pb and Cu spiked soil proved the most effective amendment in modifying the distribution pattern of Pb and Cu from acid-soluble (less bioavailable) to residual fraction (non-toxic), thereby improving the geochemical stability of contaminated soil. The application of BC (6% w/w) reduced the uptake of Pb and Cu in shoot and root by 46 and 36%, and 77 and 58%, respectively. While investigating the residual impact in tomato, the uptake was decreased by 36 and 66% for Pb and 29 and 61% for Cu in shoot and root samples, respectively. With the application of BC (6% w/w), the concentrations of Pb and Cu in the shoot portion of tomato were below the permissible limits as set by the world health organization. The application of SSP was more effective in reducing TCLP-Pb to 0.2 mg L−1 in metals spiked soil compared to the other amendments. However, the bioavailability of Cu was increased with increasing SSP addition. In conclusion, the application of BC was more effective in reducing Pb and Cu phytoavailability through immobilization in contaminated soil compared to the other organic and inorganic amendments.

Accumulation Of Heavy Metal Lead (Pb) And Cadmium (Cd) In Halophila ovalis And Thalassia hemprichii As Agents Of Phytoremediation In South Serangan

Seagrass ecosystem is part of the marine ecosystem that has quite important ecological role. Halophila ovalis and Thalassia hemprichii are seagrass species have the potential to become an agent of phytoremediation by determining the concentration of heavy metals Pb and Cd that have accumulated in them. This study was conducted in January 2018 in Southern Serangan Beach. The purpose of investigating the concentration of heavy metals in water, sediments, roots and leaves of seagrass and determine the bioaccumulation, translocation character and can be made as an agent for phytoremediation. The method used is purposive random sampling method, determined by 3 point. The point is determined from the condition closest to the port Benoa to the outermost point the bay mouth. Determination of station points is considering the presence of the most seagrasses. Results obtained in this study obtained average Pb concentration in water 0.0521 ppm, average metal Cd 0.1652 ppm, the average sediment Pb 75.8574 ppm, Cd 15.33593 ppm, concentration of Pb and Cd in roots and leaves of H. ovalis and T. hemprichii respectively Pb 42.4940 ppm, 45.5334 ppm, and 35.6207 ppm, 38.3931 ppm. Metal Cd 12.9708 ppm 14.8581 ppm Bioaccumulation value of seagrass is accumulator plants. Value of Pb and Cd translocation factors in seagrass H. ovalis (phyto-extraction) seagrass T. hemprichii Pb (phyto-extraction) and Cd (fitostabilization) phytoremediation values by both types of seagrass are greater in remediating heavy metal cadmium, meaning that both types of seagrass are better used for phytoremediation agents of heavy metal cadmium.

Effects of Soil Amendments on Heavy Metal Immobilization and Accumulation by Maize Grown in a Multiple-Metal-Contaminated Soil and Their Potential for Safe Crop Production.

Soil amendments have been proposed for immobilizing metallic contaminants, thus reducing their uptake by plants. For the safe production of crops in contaminated soil, there is a need to select suitable amendments that can mitigate heavy metal uptake and enhance crop yield. The present experiment compared the effects of three amendments, hydroxyapatite (HAP), organic manure (OM), and biochar (BC), on plant growth and heavy metal accumulation by maize in an acidic soil contaminated with Cd, Pb, and Zn, and their potential for safe crop production. Toxicity characteristic leaching procedure (TCLP) tests, energy dispersive X-ray spectroscopy (EDS) analysis, and X-ray diffraction (XRD) analysis were used to evaluate the effectiveness and mechanisms of heavy metal immobilization by the amendments. The results showed that shoot and root biomass was significantly increased by HAP and 1% OM, with an order of 1% HAP > 0.1% HAP > 1% OM, but not changed by 0.1% OM and BC (0.1% and 1%). HAP significantly decreased Cd, Pb, and Zn concentrations in both shoots and roots, and the effects were more pronounced at the higher doses. OM decreased the shoot Cd and Pb concentrations and root Zn concentrations, but only 1% OM decreased the shoot Zn and root Pb concentrations. BC decreased the shoot Cd and Pb concentrations, but decreased the shoot Zn and root Pb concentrations only at 1%. HAP decreased the translocation factors (TFs) of Cd, Pb, and Zn (except at the 0.1% dose). OM and BC decreased the TFs of Cd and Zn, respectively, at the 1% dose but showed no significant effects in other cases. Overall, plant P, K, Fe, and Cu nutrition was improved by HAP and 1% OM, but not by 0.1 OM and BC. Soil pH was significantly increased by HAP, 1% OM, and 1% BC, following an order of 1% HAP > 1% OM > 0.1% HAP > 1% BC. The TCLP levels for Cd, Pb, and Zn were significantly reduced by HAP, which can be partly attributed to its liming effects and the formation of sparingly soluble Cd-, Pb-, and Zn-P-containing minerals in the HAP-amended soils. To some extent, all the amendments positively influenced plant and soil traits, but HAP was the optimal one for stabilizing heavy metals, reducing heavy metal uptake, and promoting plant growth in the contaminated soil, suggesting its potential for safe crop production.

Trace metal biogeochemical responses following wood ash addition in a northern hardwood forest

Wood ash may be useful as a forest soil amendment in Canada, but trace metals can have detrimental effects if they accumulate in, or are transported from, forest ecosystems. Metal concentrations in soil water and sugar maple (Acer saccharum Marsh.) seedling tissue chemistry were measured in a north temperate hardwood forest over 4 years following a biomass boiler ash addition field trial. Twenty plots (3 m × 3 m) were established in Haliburton Forest with both fly and bottom ash treatments of 0, 4, and 8 Mg·ha−1 with four replicates, and tension lysimeters were positioned in each plot at 30, 50, and 100 cm depths. Over the 4 years, soil water metal concentrations in treated plots were not significantly different from those of the control plots. No differences in metal concentrations in foliage of sugar maple seedlings could be detected, but there were significantly higher concentrations of some metals (Al, Fe, Zn, Pb, Ni, and Sr) in roots of treated plots. Simulated drought mobilized several metals in upper mineral soil, but this mobilization occurred similarly in controls and ash-treated soils. These results suggest that doses below 8 Mg·ha−1 industrial wood ash with trace metal concentrations below Canadian regulatory limits do not cause an increase in trace metal mobility or availability in northern hardwood forests with acidic soils during the first 5 years after application.

Effects of Heavy Metal Contents on Phyllosphere and Rhizosphere Fungal Communities for Bothriochloa ischaemum in Copper Tailings Area

There are complex interrelationships between plant microorganisms (phyllosphere and rhizosphere) and host plants, which can promote plant growth and enhance the tolerance of host plants to stress. In this study, we selected the dominant species Bothriochloa ischaemum as the research subject in a copper tailings dam. Using high-throughput sequencing, we investigated the structures of the fungal communities and diversities in the phyllosphere and rhizosphere of B. ischaemum. This study also explored the effects of heavy metal content on fungal community characteristics. The results showed that Ascomycota and Basidiomycota were the dominant phyla in the phyllosphere and rhizosphere of B. ischaemum. The diversities and richness of the rhizosphere fungal community were higher than that of the phyllosphere fungal community. The diversities of rhizosphere and phyllosphere fungal communities was affected by different heavy metals. Phyllosphere fungal diversity was mainly affected by the content of Zn and Cu in leaves, and the content of Pb in roots was the key factor affecting the diversity of the rhizophere fungal community. Furthermore, Pleosporaceae had a very significant positive correlation with Cd in the phyllosphere, and Nectriaceae had a significant positive correlation with Zn in the rhizosphere. These fungal communities could be used as indicators of ecological recovery in areas with heavy metal pollution. The results could provide an ecological basis for the exploration and utilization of phyllosphere or rhizosphere fungi resources during ecological restoration processes. This study also provides guidance for selecting the plant-microbial symbionts during ecological restoration in areas with heavy metal pollution.

Appraisal of tissue compartmentalized metal(loid) uptake by rice

Numerous physical and chemical approaches are existing for metal elimination from the soil; nonetheless, phytoremediation is regarded as one of the paramount effective and cost-friendly approach. However, ample work has been done all over the world to appraise phytoremediation capability of plants in controlled conditions; only limited studies are existing on metal uptake abilities of plants cultivated under natural conditions. So, the present work estimates the phytoremediation potential of rice, imperative food crop cultivated in agricultural soils of Punjab with key objective to appraise the accretion and transport of metals (Zn, Cu, Mn, Cr, Cd, Ni, As and Pb) in roots, stems and leaves. Data was analysed by using Pearson’s correlation analysis and heatmap analysis. Correlation analysis exhibited strong relationship among metals in soil and different tissues of rice. pH, soil organic carbon and phosphorus showed significant correlation with studied metal(loid)s in the soils affecting their availability and retention. In soil, highest and lowest concentrations of Zn and Pb were found for different sites, respectively. In rice among all the metals, Ni was found maximum in roots and stems, while Zn content was recorded maximum in leaves. The results of bioaccumulation factor and translocation factor were obtained above one for Zn, Mn, Ni, Cr, Cd and Pb, signifying the phytoremediation potential of rice in natural conditions.

Phytoremediation of Nickel and Lead Contaminated Soils by Hedera colchica

ABSTRACT Phytoremediation is an effective and affordable technological solution to extract or remove metal pollutants from contaminated soil. In this study, the ability of Hedera colchica plant for the removal of Pb and Ni metals with different concentrations from soil and also metal efficacy on morphological parameters of the plant were investigated. The morphological results showed that as the concentration of heavy metals increases in soil up to 600 mg.kg−1 soil, the dry weights of shoot and root reduce about 46 and 60% with Pb and 18 and 51% with Ni, and also total length up to 31% with Pb and 3% with Ni, respectively. The maximum concentration of Pb and Ni in shoots (92.2 and 77.2 mg.kg−1 Dwt, respectively) and roots (252 and 218 mg.kg−1, respectively) were recorded in the cultivated plant in soil amended with metal high concentrations. The highest bio-concentration (BCF) and translocation factor (TF) were recorded for Pb in the roots. In addition, this study showed that H. colchica plant was more favorable for Pb uptake compared to Ni, but we do not suggest using it for the remediation of the contaminated soils with Pb and Ni metals.

The yield potential and growth responses of licorice (Glycyrrhiza glabra L.) to mycorrhization under Pb and Cd stress

The effects of mycorrhization (inoculation and non-inoculation) on growth and quality of two ecotypes (Baft and Ramjerd) of Glycyrrhiza glabra L. under heavy metals stress (0, 300 Pb + 20 Cd (H1) and 600 Pb + 40 Cd (H2) (mg kg−1) was investigated. Higher concentration of heavy metals decreased shoot dry weight in Baft (7.05%) and Ramjerd (43.34%) than control. Root dry weight increased in mycorrhizal Baft (28.23%) and Ramjerd (31.84%) ecotypes under H2 than non-mycorrhizal plants. In mycorrhizal plants, root colonization percentage decreased 37.07% in H2 than control. Increasing heavy metals concentration led to increase of total antioxidant activity and total phenol content. Mycorrhizal Ramjerd showed the lowest shoot Pb concentration in both heavy metals concentrations and the highest root Pb concentration (107.25% higher than non-mycoorhizal one) in H2. For both ecotypes, the lowest shoot Cd concentration observed in mycorrhizal plants under H1 and mycorrhizal plants had more root Cd concentration (33.83 mg kg−1 dry matter) than non-mycorrhizal ones. In both concentrations of heavy metals, the lowest Pb (0.026) and Cd (0.153) translocation factor (TF) observed in mycorrhizal plants. Based on the results, licorice with TF< 1 is not a hyperaccumulator plant but stabilizes Cd and Pb in root. Novelty statement: Licorice is a well-known medicinal plant that its root and rhizome contains diverse applications in pharmaceutical and food industries. The main source of licorice supply is through harvesting from natural habitats of Iran (one of the first exporters of licorice in the world), which during the last years have been exposed to heavy metals contamination. Therefore, the growth response of the plant in polluted habitats and most importantly, the concentration of heavy metals especially in belowground parts of the plant need more consideration. Hence, this research was carried out with an objective to investigate growth and yield potential response of two ecotypes of licorice to mycorhization under heavy metal stress (Cd and Pb) and the mechanism of heavy metal management in above and belowground parts of licorice in order to achieve its potential for further sustainable phytoremediation programs and most importantly considering the heavy metal accumulation in rhizomes and roots in accordance with world standards for medicinal and edible consumption.

Growth and lead uptake by Parkinsonia aculeata L. inoculated with Rhizophagus intraradices

The increased lead (Pb) pollution in the biosphere has resulted in serious environmental problems, so it is essential to evaluate phytoremediation strategies for contaminated soils. This study evaluated the growth and Pd absorption capacity of Pakinsonia aculeata, inoculated with an arbuscular mycorrhizal fungus (Rhizophagus intraradices) over 18 weeks under greenhouse conditions. Treatments included inoculated and non-inoculated plants combined with six Pb concentrations (0, 40, 80, 160, 320, 640 mg·L−1) in the form of Pb(NO3)2. Results showed that mycorrhizal colonization in inoculated plants ranged from 5.0 to 6.7% and favored plant growth. Pb levels and AMF-inoculation had no effects on chlorophyll fluorescence values. AMF-plants absorbed significantly more Pb in roots (237.97 mg·kg−1) than control plants (202.85 mg·kg−1), as well as high translocation to shoots (27.02 mg·kg−1) under the high Pb dose. The increase in Pb concentration reduced the P concentration in roots, and the P and N concentrations in shoots; however, the absorption and translocation of Ca and Mg was increased in shoots. Inoculation of R. intraradices improved both growth and Pb uptake of P. aculeata, under greenhouse conditions suggesting that this tree species may be potentially studied for detoxifying Pb-polluted soils.

The unusual property of the sand violet, Viola rupestris, to cope with heavy metal toxicity

For investigating the capacity for accumulation of heavy metals and their avoidance, a number of parameters were compared in plants of the sand violet (Viola rupestris) growing on a heavy metal heap and on a non-contaminated reference site, both rich in limestone. The plants collected from both sites showed large differences in the numbers and sizes of reproductive structures and the content of heavy metals both in roots and leaves. The accumulation capability for Zn, Cd and Pb in roots and leaves of the violets from the heavy metal site was high although not comparable to some heavy metal plants. High numbers of oxalate crystals were observed in plants from the polluted site which may serve to detoxify not only Ca, but also Zn, Cd and Pb. Almost all reproductive structures examined were lower in numbers and sizes in the plants from the contaminated site compared to the situation in the reference violets. The heavy metal content in the capsules of the plants from the heavy metal site, was, however, not as high as in roots and leaves which is seemingly a general phenomenon of plants occurring on heavy metal soils and being exposed to the toxicity of these elements. The present findings could serve as a basis for molecular studies on the adaptions of non-metallophytic plants to stress caused by heavy metal toxicity in contaminated soils.

Potential role of compost mixed biochar with rhizobacteria in mitigating lead toxicity in spinach

Consumption of heavy metals, especially lead (Pb) contaminated food is a serious threat to human health. Higher Pb uptake by the plant affects the quality, growth and yield of crops. However, inoculation of plant growth-promoting rhizobacteria (PGPR) along with a mixture of organic amendments and biochar could be an effective way to overcome the problem of Pb toxicity. That’s why current pot experiment was conducted to investigate the effect of compost mixed biochar (CB) and ACC deaminase producing PGPR on growth and yield of spinach plants under artificially induced Pb toxicity. Six different treatments i.e., control, Alcaligenes faecalis (PGPR1), Bacillus amyloliquefaciens (PGPR2), compost + biochar (CB), PGPR1 + CB and PGPR2 + CB were applied under 250 mg Pb kg-1 soil. Results showed that inoculation of PGPRs (Alcaligenes faecalis and Bacillus amyloliquefaciens) alone and along with CB significantly enhanced root fresh (47%) and dry weight (31%), potassium concentration (11%) in the spinach plant. Whereas, CB + Bacillus amyloliquefaciens significantly decreased (43%) the concentration of Pb in the spinach root over control. In conclusion, CB + Bacillus amyloliquefaciens has the potential to mitigate the Pb induced toxicity in the spinach. The obtained result can be further used in the planning and execution of rhizobacteria and compost mixed biochar-based soil amendment.

Differential effects of three amendments on the immobilisation of cadmium and lead for Triticum aestivum grown on polluted soil.

Conventional chemical soil amendments and novel material biochars have been widely reported for the immobilisation of cadmium (Cd) and lead (Pb) in polluted soil. However, information regarding their comparative effectiveness is poor. In the present study, rice husk biochar (RHB) was compared with two chemical soil amendments including hydroxyapatite (HAP) and hydrated lime (HDL) for their effectiveness to enhance plant growth and the reduction of Cd uptake and translocation by Triticum aestivum L. grown in heavy-metal-polluted soil. Compared with control and two chemical soil amendments, RHB rapidly improved wheat growth. The HAP, HDL, and RHB treated plants retained Cd and Pb in roots and restricted their translocation. The RHB treatment had the best effect on growth, yield promotion and the reduction of Cd and Pb in wheat grain. Furthermore, the soils treated with RHB and HAP showed lower DTPA-extracted Cd concentrations, and the maximum reduction was observed in HAP-amended soil. However, the DTPA-extracted Pb concentration was not significantly decreased after the application of two chemical soil amendments for 40days; the maximum reduction was found in soil treated with RHB for 80days. In all treatments, Cd in post-harvest soil was mainly present in exchangeable, carbonate bound, and Fe-Mn oxide Cd, while the dominant chemical form of Pb was Fe-Mn oxide Pb. Three soil amendments application decreased exchangeable and organic bound- Cd and Pb levels. HAP and RHB displayed significantly immobilisation for soil Cd and reduced translocation of heavy metal as well as its availability in soil, but the HAP had significant inhibition on growth of wheat in contaminated soil. Therefore, RHB shows a promising potential for the reduction of Cd and Pb bioaccumulation in grains from wheat grown on heavy-metal-polluted soils.

Morphological, physiological, and genotoxic effects of heavy metal bioaccumulation in Prosopis laevigata reveal its potential for phytoremediation.

Mining industry generates large volumes of waste known as mine tailings, which contain heavy metals (HMs) that generate a risk to environmental health. Thus, remediation of HM pollution requires attention. In this study, HM bioaccumulation, genotoxic damage, and morphological and physiological changes in the tree species Prosopis laevigata were evaluated in order to assess its potential for remediation of mine tailings. P. laevigata plants were established in two treatments (reference substrate and tailing substrate) under greenhouse conditions. Every 2months, six individuals were selected per treatment for 1year. From each individual, macromorphological (height, stem diameter, and number of leaves), micromorphological (stomatal coverage and stomatal index), and physiological parameters (chlorophyll content) were evaluated, as well as the concentration of Pb, Cu, Cd, Cr, Fe, and Zn in root and foliar tissue. Genetic damage was assessed by the comet assay in foliar tissue. These parameters were evaluated in adult individuals established in mine tailings. Roots bioaccumulated significantly more HM compared to foliar tissue. However, the bioaccumulation pattern in both tissues was Fe > Pb > Zn > Cu. The plants in tailing substrate reduced significantly the morphological and physiological characters throughout the experiment. Only the bioaccumulation of Pb affected significantly the levels of genetic damage and the number of leaves, while Zn reduced plant height. The percentage of plants that have translocation factor values greater than 1 are Cu (92.9) > Fe (85.7) > Pb (75.0) > Zn (64.3). P. laevigata has potential to phytoremediate environments contaminated with metals, due to its dominance and establishment in abandoned mine tailings, and its ability to bioaccumulate HM unaffecting plant development, as well as their high levels of HM translocation.

Efficiency of Pinus nigra J.F. Arnold in removing pollutants from urban environment (Plovdiv, Bulgaria).

The aim of this study was to assess the efficiency of urban vegetation in removing pollutants from the environment using Pinus nigra J.F. Arnold as a model tree. For this purpose, the concentrations of some heavy metal and potentially toxic elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, U, and Zn) in needles, branches, and roots of P. nigra, as well as in the surrounding soil, have been analyzed and the removal capacity has been estimated on the basis of element translocation. The relationship between ecosystem services provisioning and plant well-being was also analyzed through physiological (photosynthetic pigment content and ratio) and anatomical (leaf injuries appearance) indicators. Enrichment factor, translocation factor, bioaccumulation factor, and index of translocation were calculated in order to assess the urban impact and removal efficiency of sampled trees, as well as the general transport of trace elements between the studied plant's organs as results of wet and dry atmospheric deposition. Anthropogenic pollution with As, Cd, and Pb was proven in whole urban environment, so these high values of translocation through pine trees have given an added value to the regulating ecosystem services of urban vegetation. Searching and planting of trees with higher removal efficiency could be crucial for improving quality of urban environment.

Heavy Metals Concentration in Mango (Mangifera indica L.) Grown around Some Gold Mining Areas of Zamfara State, Nigeria

Aims: This study was aimed at determining the concentration of heavy metals (Pb, Cd, Fe and Au) in mango plant parts (roots, stem barks, leaves and fruits) from two gold mining areas (Maraba and Duke) and the control (Kadauri) in Zamfara State, Nigeria for establishment of a baseline data for these metals and determining the suitability of the mango fruit for consumption.&#x0D; Study Design: Analytical study design was applied in a stratified manner for the research.&#x0D; Place and Duration of Study: The study was carried out in the environmental technology laboratory, National Research Institute for Chemical Technology (NARICT), Zaria, Nigeria between March and August 2019.&#x0D; Methodology: A cumulative total of 96 samples of plant parts (roots, stem barks, leaves and fruits) were collected and analysed for Lead, Cadmium, Iron and Gold using Atomic Absorption Spectrophotometer (AAS) after digestion with a mixture of 20 ml HNO3 and 8 ml HClO4.&#x0D; Results: The results obtained for the mean metal concentrations were; most abundant, Pb (62.07 ± 54.09 mg/kg) in mango roots from Duke and the least abundant, Cd (0.52 ± 0.44 mg/kg) in fruits from Kadauri. All the metals had very high (&gt; 0.5) translocation factors indicating fast movement from the roots to the shoots while the mean values of these metals in the fruits were found to be above the WHO and FAO maximum permissible limits which shows high level of contamination as a result of gold mining activities. Metals generally occurred in the order: Pb&gt;Fe&gt; Au &gt; Cd and they differed across sampling stations with the mining areas having significantly (P&lt;0.05) higher values than the control.&#x0D; Conclusion: Heavy metals concentration in mango plant was found to be generally higher than the permissible limits hence the fruits are considered unsuitable for human consumption.

Performance of Streptomyces pactum-assisted phytoextraction of Cd and Pb: in view of soil properties, element bioavailability, and phytoextraction indices.

Microbe-assisted phytoremediation provides an eco-friendly and cost-effective approach to reclaim Cd- and Pb-contaminated soils. In this work, incubation and pot experiments were established to investigate the effect of Streptomyces pactum (Act12) combined with compost on soil physicochemical properties, enzymatic activities, and thereby acted on phytoextraction of Cd and Pb by using potherb mustard (Brassica juncea Coss.). The addition of Act12 and compost increased EC (7.2%), available phosphorus (P) (14.9%), available potassium (K) (17.0 folds), DOC (37.7%), OM (2.8 folds), urease (49.8%), dehydrogenase (2.2 folds), and alkaline phosphatase (23.0 folds) of soil, while reduced pH (7.7%) compared with control. Significant decrease of available Cd and Pb uptake was observed after adding compost and Act12 by 29.1% and 32.2%. Presence of compost and Act12 enhanced the biomass by 3.98 folds and 1.83 folds in shoots and roots of plant. Results showed the assimilation of Cd and Pb in shoots was increased by 103.8% and 48.7% due to the increased of biomass. Meanwhile, the rhizosphere effect of soil microorganisms increased the uptake of Cd (60.4%) and Pb (19.2%) in roots. These findings suggested that Act12 joined with compost-strengthened potherb mustard phytoremediation of Cd- and Pb-polluted soils, which may provide new insights into the clean-up of mining-contaminated soils in field practice.

Response of Berula erecta to Lead in Combination with Selenium.

Tissue culture of Berula erecta is suitable cultivation system for research purposes connected with contamination and phytoremediation studies. In previous investigation we determined the optimal dose concentration at which Se stimulates plant growth and positively affects the antioxidative status in this experimental system. In current study, we investigate its response to exposure to lead (Pb) and further the possible protective effect of Se(IV) against Pb exposure. Plants were grown in 10 and 50mg Pb L-1 solution without and with added Se (0.1mg L-1) for six weeks. Plants possessed a high affinity to uptake Pb and Se in roots. Addition of Pb inhibited roots elongations and the plant height. In contrast, the combined effect of Se + Pb treatment was reflected in increased weight of plants when compared to Pb treatment alone. Pb decreased the amount of chlorophylls and consequently photochemical efficiency was lowered, whereas in Pb + Se treatment the photochemical efficiency was higher. Furthermore, Pb treatment caused a gradual increase in glutathione in both roots and shoots, however, to a greater percentage in shoots when compared to controls. Exposure to both Pb and Se did not cause any significant changes in root's glutathione level when compared to Pb treatment alone. In shoots, the combined treatment lowered the glutathione significantly, but the levels remained 50% above those of untreated control samples, reflecting that this might be related with the antioxidative effects of Se treatment.

Toxicity, migration and transformation characteristics of lead in soil-plant system: Effect of lead species

Lead (Pb) is a typical hazardous element of high concern in species characteristics involving toxicity, migration and transformation. A greenhouse experiment was conducted using Solanum nigrum L. grown in soils treated by divalent (Pb2+), tetravalent (Pb4+), trimethyl (TML) and triethyl (TEL) lead for 60 days. Results of physio-biochemical parameters indicated Pb toxicity was ranked as TEL > TML > Pb2+ > Pb4+ in a dose-dependent manner, and the correlation levels of organic species were higher than inorganic species. S. nigrum L. adopted phytostabilization strategy through fixing Pb in roots and restricting its transfer to shoots. More phytotoxic Pb was absorbed from soils treated by Pb2+ than Pb4+ as well as TEL than TML. In soils, inorganic Pb species were mainly present in residues while organic Pb species in Fe/Mn oxide and exchangeable fractions. Although most of Pb species in plant existed in the low-bioavailable extractions of 1 M NaCl and 2% HAC, the water-soluble Pb extracted by d-H2O and 80 % ethanol were increased to a large extent under high-level exposure. The occurrence of reduction and (de)alkylation were considered as the major pathways in the biotransformation of Pb species. This study will conduce to the ecological risk management for Pb-contaminated soils.

Co-remediation of Pb Contaminated Soils by Heat Modified Sawdust and Festuca arundinacea

This research aimed to explore the potential and mechanism of heat modified sawdust combined with Festuca arundinacea for the remediation of Pb-contaminated soil. We determined Pb concentration and biochemical indices in plants and soils, analyzed microbial communities in soil, and studied Pb distribution in subcellular and tissues. Under co-remediation of 5% material addition and Festuca arundinacea, the concentration of Pb in soil decreased. Pb toxicity of Festuca arundinacea was alleviated by 2% material addition through the promotion of plant growth and reduction of oxidative stress. In addition, soil enzyme activities and microbial community in contaminated soil were promoted by the application of co-remediation. Festuca arundinacea cell wall accumulated a large amount of Pb, and the addition of material promoted the accumulation of Pb in Festuca arundinacea root. The concentration of Pb in the shoot of the plant treated with 2% material was higher than that of the plant treated with 5% material, and the damage of Festuca arundinacea leaves was lower under 2% treatment. The combination of heat modified sawdust and Festuca arundinacea promoted the adsorption of Pb by plants, and protected the growth of plants.