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1.
The application of vetiver grass (Chrysopogon zizaniodes) for phytoremediation of heavy metal contaminated soils can be promoted by economic return through essential oil production. Four levels of lead (0, 500, 2000, and 8000 mg kg(-1) dry soil), copper (0, 100, 400, and 1600 mg kg(-1) dry soil) and zinc (0, 400, 1600, and 6400 mg kg(-1) dry soil) were used to study their effects on vetiver growth, essential oil composition and yield. This study also investigated the effect of nitrogen concentrations on vetiver oil yield. Vetiver accumulated high concentrations of Pb, Cu and Zn in roots (3246, 754 and 2666 mg kg(-1), respectively) and small amounts of contaminants in shoots (327, 55, and 642 mg kg(-1), respectively). Oil content and yield were not affected at low and moderate concentrations of Cu and Zn. Only the application of Pb had a significant detrimental effect on oil composition. Extraction of vetiver essential oils by hydrodistillation produced heavy metal free products. High level of nitrogen reduced oil yields. Results show that phytoremediation of Cu and Zn contaminated soils by vetiver can generate revenue from the commercialization of oil extracts.  相似文献   

2.
The aim of this study was to investigate effect of calcium on growth, survival, essential oil yield and chemical compositions of vetiver grass grown on lead contaminated soils. Calcium inform of CaCO3 (0, 2000, 4000, 6000 mg Ca kg(-1)) was added to river sand soils containing 4000 mg Pb kg(-1) dry soil. Results showed that, in the absence of calcium treatment, no plants survived after 2 weeks of cultivation, while the rest grew well to the end of the experimental period (42 weeks). Calcium treatments generally resulted in a slight decrease in biomass. Interestingly, an increase in calcium over 2000 mg kg(-1) did not result in a decrease in accumulation of lead in vetiver roots and shoots. The levels of lead in roots and shoots under calcium treatments were around 2000 and 90 mg kg(-1) dry weight, respectively. The addition of CaCO3 did not improve vetiver essential oil yield and chemical composition compared to the control. A level of applied CaCO3 about half of the lead concentration in soils was sufficient to improve vetiver growth and survival, and accumulate high concentrations of lead in the roots. This finding can be applied for re-vegetation of lead contaminated soils using vetiver.  相似文献   

3.
Pot culture experiments were established to determine the effects of colonization by arbuscular mycorrhizal fungi (AMF) (Glomus mosseae and G. sp) on maize (Zea mays L.) grown in Pb, Zn, and Cd complex contaminated soils. AMF and non-AMF inoculated maize were grown in sterilized substrates and subjected to different soil heavy metal (Pb, Zn, Cd) concentrations. The root and shoot biomasses of inoculated maize were significantly higher than those of non-inoculated maize. Pb, Zn, and Cd concentrations in roots were significantly higher than those in shoots in both the inoculated and non-inoculated maize, indicating the heavy metals mostly accumulated in the roots of maize. The translocation rates of Pb, Zn, and Cd from roots to shoots were not significantly difference between inoculated and non-inoculated maize. However, at high soil heavy metal concentrations, Pb, Zn, and Cd in the shoots and Pb in the roots of inoculated maize were significantly reduced by about 50% compared to the non-inoculated maize. These results indicated that AMF could promote maize growth and decrease the uptake of these heavy metals at higher soil concentrations, thus protecting their hosts from the toxicity of heavy metals in Pb, Zn, and Cd complex contaminated soils.  相似文献   

4.
The abandoned chromite-asbestos mines are located in the Roro hills, West Singhbhum, Jharkhand, India, where mining operation ceased in 1983, and since then these mines are causing environmental pollution. The present study was planned to phytoremediate these metalloid and metal contaminated mine waste by using two aromatic grasses, Cymbopogon citratus and Chrysopogon zizanioides by applying different proportions of amendments (chicken manure, farmyard manure and garden soil). Mine waste has neutral pH, low electrical conductivity and organic carbon with higher concentration of total metals (Cr and Ni) as compared to soil. Application of manures resulted significant improvements of mine waste characteristics and plant growth, reduction in the availability of total extractable toxic metals (Cr, Ni) and increase in Mn, Zn and Cu concentration in the substrate. The maximum growth and biomass production for C. citratus and C. zizanioides were found in T-IV combination comprising of mine waste (90%), chicken manure (2.5%), farmyard manure (2.5%) and garden soil (5%). Addition of T-IV combination also resulted in low Cr and Ni accumulation in roots and reduction in translocation to shoots. Study indicates that C. citratus and C. zizanioides can be used for phytostabilization of abandoned chromite-asbestos mine waste with amendments.  相似文献   

5.
The effectiveness of an in situ heavy metals fixation technique aimed at converting contaminants to low solubility and low bioavail-ability forms, eliminating the risk posed by oxidic tailings and contaminated soils, was investigated. Calcium oxyphosphate salt (Ca(H2PO4)2·H2O) was used as a stabilizing agent for oxidic tailings and contaminated soils originating from Montevecchio, Sardinia, Italy. Stabilization was effected by mixing the contaminated soil or oxidic tailing sample with calcium oxyphosphate salt at various doses. The effectiveness of stabilization was evaluated by USEPA TCLP standard toxicity testing. Complementary EDTA extraction tests and biological tests using beans Phaseolous vulgaris as plant indicator were carried out. The toxicity of Pb and Cd was reduced below TCLP regulatory limits at calcium oxyphosphate doses higher than 0.7 and 0.2% w/w for soils and tailings, respectively. Lead solubility according to the EDTA test decreased with phosphate dose for both materials tested. Lead uptake by plant leaves and roots from the soil sample decreased with the phosphate addition, while Cd uptake remained almost constant. An adverse effect on plant growth and Zn uptake was observed for calcium oxyphosphate dose up to 1.1% w/w. Based on the results, a remediation scheme for oxidic tailings and contaminated soils is proposed.  相似文献   

6.
Vetiver (Chrysopogon zizanioides) is a fast-growing, high biomass producing plant employed for environmental rehabilitation. The study evaluated the effects of arbuscular mycorrhizal fungi (AMF) on the growth and trace element phytoextracting capabilities of vetiver in a substrate containing coalmine wastes in Southern Brazil. AMF included Acaulospora colombiana, Acaulospora morrowiae, Acaulospora scrobiculata, Dentiscutata heterogama, Gigaspora margarita, and Rhizophagus clarus. Among those, A. colombiana, G. margarita, and R. clarus promoted higher growth. AMF stimulated average increments in the accumulated P of 82% (roots), 194% (shoots first harvest—90 days) and 300% (shoots second harvest—165 days) and affected the phytoextraction of trace elements by vetiver, with larger concentrations in the roots. Plants inoculated with A. colombiana, A. morrowiae, and A. scrobiculata, in addition to the control, presented the highest levels of Cu and Zn in the roots. Overall, G. margarita stimulated the highest production of biomass, and, therefore, showed the most significant levels of trace elements in the plants. This work shows the benefits of certain AMF (especially A. morrowiae, G. margarita, and R. clarus) for the production of biomass and P uptake by vetiver, demonstrating the potential of those species for the rehabilitation of coal-mine-degraded soils.  相似文献   

7.
Distribution of extractable heavy metals in different soil fractions   总被引:1,自引:0,他引:1  
Abstract

Due to the difficulties of precisely characterizing environmentally contaminated soil, the effects of heavy metals on plants are studied using uncontaminated soil spiked with known quantities of heavy metals. One problem in using spiked soils is how accurately the distribution of metals mimics stabilized natural soils. We studied the distribution of cadmium, chromium, copper, lead, nickel, and zinc in soil fractions after application in soluble form. The soil samples included a control (an uncontaminated Typic Argiudoll) and two samples spiked with either a moderate or high heavy metal concentration). After application of the salts the soils were subjected to wet/dry cycles over the course of three months. The soils were fractionated using a sequential chemical extraction procedure employing: (1) CaCl2,(2) NaOH, (3) Na2EDTA and (4) HNO3, HCl, and HF. Soil physical separation was carried out by ultrasonic dispersion. The heavy metal levels were determined using ICP-AES. Each heavy metal displayed a unique behavior when added to soil in the form of soluble salts. Cadmium and zinc remained in the soluble fraction, indicating that no equilibrium was attained, while nickel primarily appeared in the insoluble fraction. Chromium, copper and lead were distributed among various soil chemical fractions. The highest levels of all metals appeared in the clay fraction except lead which was mainly present in the silt fraction.  相似文献   

8.
High biomass producing plant species, such as Helianthus annuus, have potential for removing large amounts of trace metals by harvesting the aboveground biomass if sufficient metal concentrations in their biomass can be achieved However, the low bioavailability of heavy metals in soils and the limited translocation of heavy metals to the shoots by most high biomass producing plant species limit the efficiency of the phytoextraction process. Amendment of a contaminated soil with ethylene diamine tetraacetic acid (EDTA) or citric acid increases soluble heavy metal concentrations, potentially rendering them more available for plant uptake. This article discusses the effects of EDTA and citric acid on the uptake of heavy metals and translocation to aboveground harvestable plant parts in Helianthus annuus. EDTA was included in the research for comparison purposes in our quest for less persistent alternatives, suitable for enhanced phytoextraction. Plants were grown in a calcareous soil moderately contaminated with Cu, Pb, Zn, and Cd and treated with increasing concentrations of EDTA (0.1, 1, 3, 5, 7, and 10 mmol kg(-1) soil) or citric acid (0.01, 0.05, 0.25, 0.442, and 0.5 mol kg(-1) soil). Heavy metal concentrations in harvested shoots increased with EDTA concentration but the actual amount of phytoextracted heavy metals decreased at high EDTA concentrations, due to severe growth depression. Helianthus annuus suffered heavy metal stress due to the significantly increased bioavailable metal fraction in the soil. The rapid mineralization of citric acid and the high buffering capacity of the soil made citric acid inefficient in increasing the phytoextracted amounts of heavy metals. Treatments that did not exceed the buffering capacity of the soil (< 0.442 mol kg(-1) soil) did not result in any significant increase in shoot heavy metal concentrations. Treatments with high concentrations resulted in a dissolution of the carbonates and compaction of the soil. These physicochemical changes caused growth depression of Helianthus annuus. EDTA and citric acid added before sowing of Helianthus annuus did not appear to be efficient amendments when phytoextraction of heavy metals from calcareous soils is considered.  相似文献   

9.
ABSTRACT

Soil contamination with heavy metals has become a worldwide concern. A sustainable technology to mitigate heavy metal contamination is extremely important. Phytoremediation is a cost-effective method, environmentally friendly, and esthetically pleasing. The aim of this study was to investigate the potential of Vetiver phytoremediation of soils contaminated with heavy metals. This research was conducted as a factorial design with four different heavy metals (lead, cadmium, manganese, and nickel) with three varying levels and also three replications for each treatment. Statistical analysis of data was performed using SPSS19 software and analysis of variance, Duncan and Pearson correlation tests. The results showed that, the highest uptake rate was related to lead metal with 282.45 mg/kg of dry soil and 83.4% uptake percentage. Then, the mean and percentage of adsorption for cadmium, nickel and manganese were 248.3 mg/kg (53.2%), 69.4 mg/kg (65.5%), and 63.29 mg/kg (61%), respectively. Lead was found to be the main component of uptake by Vetiver plant. It was found that the roots of the plant have absorbed more heavy metals than the shoots. And at the roots in total 1089.05 and on average 363.01 mg/kg and at the shoots 901.19 and on average 300.39 mg/kg, the metals used were adsorbed on three levels and four treatments. The results of analysis of variance, Duncan test and Pearson correlation showed that the effect of applied treatments on lead uptake in roots and shoots increased significantly (P ≤ 0.05) with increasing levels of treatments. The biological concentration factor was more than one, and the transfer factor was close to one. Therefore, it can be used as a phytostablization plant. The results showed that Vetiver can be considered as a refining plant due to its vegetative characteristics, cost-effectiveness and high adaptation to environmental conditions.  相似文献   

10.
Phytoextraction capacity of trees growing on a metal contaminated soil   总被引:8,自引:1,他引:7  
Phytoremediation is an innovative biological technique to reclaim land contaminated by heavy metals or organic pollutants. In the present work, we studied the ability of five woody species to extract heavy metal (copper, zinc or cadmium) from a polluted soil to their above-ground tissues. Metal content in leaves and twigs was determined. Salix and Betula transferred zinc and cadmium to leaves and twigs, but Alnus, Fraxinus and Sorbus excluded them from their above-ground tissues. None of the species considered transferred copper to the shoots.  相似文献   

11.
In this study an ornamental plant of Althaea rosea Cavan was investigated for its potential use in the removal of Cd, Ni, Pb and Cu from an artificially contaminated soil. Effect of two different chelating agents on the removal has also been studied by using EDTA (ethylenediaminetetracetic acid) and TA (tannic acid). Both EDTA and TA have led to higher heavy metal concentration in shoots and leaves compared to control plants. However EDTA is generally known as an effective agent in metal solubilisation of soil, in this study, TA was found more effective to induce metal accumulation in Althaea rosea Cavan under the studied conditions. In addition to this, EDTA is toxic to some species and restraining the growth of the plants. The higher BCF (Bio Concentration Factor) and TF (Translocation Factor) values obtained from stems and leaves by the effects of the chemical enhancers (EDTA and TA) show that Althaea rosea Cavan is a hyper accumulator for the studied metals and may be cultivated to clean the contaminated soils.  相似文献   

12.
Arabidopsis halleri has the rare ability to colonize heavy metal‐polluted sites and is an emerging model for research on adaptation and metal hyperaccumulation. The aim of this study was to analyze the effect of plant–microbe interaction on the accumulation of cadmium (Cd) and zinc (Zn) in shoots of an ecotype of A. halleri grown in heavy metal‐contaminated soil and to compare the shoot proteome of plants grown solely in the presence of Cd and Zn or in the presence of these two metals and the autochthonous soil rhizosphere‐derived microorganisms. The results of this analysis emphasized the role of plant–microbe interaction in shoot metal accumulation. Differences in protein expression pattern, identified by a proteomic approach involving 2‐DE and MS, indicated a general upregulation of photosynthesis‐related proteins in plants exposed to metals and to metals plus microorganisms, suggesting that metal accumulation in shoots is an energy‐demanding process. The analysis also showed that proteins involved in plant defense mechanisms were downregulated indicating that heavy metals accumulation in leaves supplies a protection system and highlights a cross‐talk between heavy metal signaling and defense signaling.  相似文献   

13.
Heavy metals are from the group of problematic factors in the ecosystem that due to being non-absorbable and having physiological effects on the activity of living organisms at low concentrations are of particular importance. In this study, the ability of berry specie to absorb heavy metal of cadmium was studied. One year old seedlings of berry specie were prepared from the nursery, concentrations of zero and 100 mg per liter of cadmium chloride solution were added to the seedlings pots soil after calculation, and after a three-month period of seedling growth, shoots and roots were separated, then the concentration amount of cadmium in the samples was determined and data were examined. The results of data analysis showed that the highest rate of cadmium accumulation in stems, roots and soil in treatment concentration is 54.76, 107.75 and 8.825 mg per kg, respectively, and the rate of cadmium accumulation in total chlorophyll and sugar in treatment concentration is 3.16 and 0.6693 mg per g, respectively, and based on the results of this research berry specie is relatively suitable for remediation of soils contaminated with cadmium.  相似文献   

14.
? Premise of the study: Agricultural soils have become contaminated with a variety of heavy metals, including cadmium. The degree to which soil contaminants affect plants may depend on symbiotic relationships between plant roots and soil microorganisms. We examined (1) whether mycorrhizal fungi counteract the potentially negative effects of cadmium on the growth and fitness of flax (Linum usitatissimum) and (2) whether mycorrhizal fungi affect the accumulation of cadmium within plant parts. ? Methods: Two flax cultivars (Linott and Omega) were grown in three soil cadmium environments (0, 5, and 15 ppm). Within each cadmium environment, plants were grown in either the presence or absence of mycorrhizal fungi. Upon senescence, we measured growth and fitness and quantified the concentration of cadmium within plants. ? Key results: Soil cadmium significantly decreased plant fitness, but did not affect plant growth. Mycorrhizal fungi, which were able to colonize roots of plants growing in all cadmium levels, significantly increased plant growth and fitness. Although mycorrhizal fungi counteracted the negative effects of cadmium on fruit and seed production, they also enhanced the concentration of cadmium within roots, fruits, and seeds. ? Conclusions: The degree to which soil cadmium affects plant fitness and the accumulation of cadmium within plants depended on the ability of plants to form symbiotic relationships with mycorrhizal fungi. The use of mycorrhizal fungi in contaminated agricultural soils may offset the negative effects of metals on the quantity of seeds produced, but exacerbate the accumulation of these metals in our food supply.  相似文献   

15.
Chromium (III) accumulation in high biomass agricultural crops, sunflower (Helianthus annum) and Indian mustard (Brassica juncea) was studied using four soils (pH 4.6 to 7.6) contaminated with different rates of CrCl3.6H2O in the presence of synthetic chelate and organic acids. Chromium is essential for normal glucose metabolism in humans and animals, but its contamination and recovery from soils is of environmental concern. Adding ethylenediaminetetraacetic acid (EDTA), citric acid, or oxalic acid to Cr(III)‐contaminated soils significantly increased Cr concentration in plant shoots and roots. Adding Cr(III) complexes of EDTA, citric acid, and oxalic acid to soils dramatically increased (>200‐fold) Cr concentration in shoots and roots. Plant growth was severely decreased but was dependent on soil type, chelate rate, form, and time of chelate application. Chelates and organic acids enhanced Cr(III) accumulation, but its toxic effects were not avoided. Chromium(III) complexes were as toxic to plants as Cr(VI). The phytoaccumulation and recovery of Cr(III) from soils were limited and depended on soil type.  相似文献   

16.
Human activities have resulted in arsenic (As) and heavy metals accumulation in paddy soils in China. Phytoremediation has been suggested as an effective and low-cost method to clean up contaminated soils. A combined soil-sand pot experiment was conducted to investigate the influence of red mud (RM) supply on iron plaque formation and As and heavy metal accumulation in two wetland plant species (Cyperus alternifolius Rottb., Echinodorus amazonicus Rataj), using As and heavy metals polluted paddy soil combined with three rates of RM application (0, 2%, 5%). The results showed that RM supply significantly decreased As and heavy metals accumulation in shoots of the two plants due to the decrease of As and heavy metal availability and the enhancement of the formation of iron plaque on the root surface and in the rhizosphere. Both wetland plants supplied with RM tended to have more Fe plaque, higher As and heavy metals on roots and in their rhizospheres, and were more tolerant of As and heavy metal toxicity. The results suggest that RM-induced enhancement of the formation of iron plaque on the root surface and in the rhizosphere of wetland plants may be significant for remediation of soils contaminated with As and heavy metals.  相似文献   

17.
Summary Experiments on sitka-spruce seedlings grown in acidic peaty gley soils under green-house conditions, where the soils where doped with increasing amounts of Cd, Cu and Pb up to maximum levels of metal added of 16 ppm, 32 ppm and 400 ppm respectively, showed that the levels of Cd and Pb in shoots and roots increased with increasing levels in the soil, whereas levels of copper appeared to be independent. The addition of these three metals to the soils did not influence the uptake of other heavy metals, or of the nutrients potassium or calcium. Increases in the shoot cadmium levels significantly reduced the yields of the plant shoots. However, the plant yields were only affected by the highest level of lead that was added to the soil (400 ppm Pb) and unaffected by all the copper treatments (0–32 ppm Cu in the soil). The lengths of the sitka-spruce roots were reduced when cadmium and lead levels in the soil exceeded certain threshold concentrations (2.5 ppm total Cd, where 0.3 ppm was extractable with 0.5 M acetic acid; and 48 ppm total Pb, where 1.7 ppm was extractable). However, root lengths were not reduced by copper. This was probably related to the fact that copper appears to be relatively unavailable in the type of soil used, as only 1.1. ppm Cu was extractable from a total of 32 ppm Cu added. Root branching was apparently reduced by increases in the soil levels of cadmium, copper and lead. The roots of some control plants had symbiotic mycorrhizal associations (4 out of 19 plants), whereas the roots of all the plants grown in the soils with added heavy metals did not develop these.  相似文献   

18.
Bioleaching of heavy metals from contaminated soil was carried out using indigenous sulfur oxidizing bacterium Acidithiobacillus thiooxidans. Experiments were carried out by varying sulfur/soil ratio from 0.03 to 0.33 to evaluate the optimum ratio for efficient bioleaching of heavy metals from soil. The influence of sulfur/soil ratio on the bioleaching efficiency was assessed based on decrease in pH, increase in oxidation–reduction potential, sulfate production and solubilization of heavy metals from the soil. Decrease in pH, increase in oxidation–reduction potential and sulfate production was found to be better with the increase in sulfur/soil ratio. While the final pH of the system with different sulfur/soil ratio was in the range of 4.1–0.7, oxidation reduction potential varied from 230 to 629 mV; sulfate production was in the range of 2,786–8,872 mg/l. Solubilization of chromium, zinc, copper, lead and cadmium from the contaminated soil was in the range of 11–99%. Findings of the study will help to optimize the ratio of sulfur/soil to achieve effective bioleaching of heavy metals from contaminated soils.  相似文献   

19.
Phytoremediation is a promising option for reclaiming soils contaminated with toxic metals, using plants with high potentials for extraction, stabilization and hyperaccumulation. This study was conducted in Cameroon, at the Bassa Industrial Zone of Douala in 2011, to assess the total content of 19 heavy metals and 5 other elements in soils and phytoremediation potential of 12 weeds. Partial extraction was carried out in soil, plant root and shoot samples. Phytoremediation potential was evaluated in terms of the Biological Concentration Factor, Translocation Factor and Biological Accumulation Coefficient. The detectable content of the heavy metals in soils was Cu:70–179, Pb:8–130, Zn:200–971, Ni:74–296, Co:31–90, Mn:1983–4139, V:165–383, Cr:42–1054, Ba:26–239, Sc:21–56, Al:6.11–9.84, Th:7–22, Sr:30–190, La:52–115, Zr:111–341, Y:10–49, Nb:90–172 in mg kg?1, and Ti:2.73–4.09 and Fe:12–16.24 in wt%. The contamination index revealed that the soils were slightly to heavily contaminated while the geoaccumulation index showed that the soils ranged from unpolluted to highly polluted. The concentration of heavy metals was ranked as Zn > Ni > Cu > V > Mn > Sc > Co > Pb and Cr in the roots and Mn > Zn > Ni > Cu > Sc > Co > V > Pb > Cr > Fe in the shoots. Dissotis rotundifolia and Kyllinga erecta had phytoextraction potentials for Pb and Paspalum orbiculare for Fe. Eleusine indica and K. erecta had phytostabilisation potential for soils contaminated with Cu and Pb, respectively.  相似文献   

20.
Phytostabilization of heavy metals in contaminated soils should be subject to two conditions, the first is the choice plant must be able to stabilize heavy metals in soil, the second is the plant material which produced from the phytostabilization process must be safe and useful to avoid overload on environmental system. A field experiment was conducted out to evaluate the phytostabilization potential of two halophytes species (Atriplex lentiformis and Atriplex undulata). Compost at rates of 0, 15 and 30 ton ha?1 was used to examine its role in plant growth and heavy metals uptake. The high rate of compost (30 ton ha?1) decreased zinc (Zn) concentrations in the leaves of A. lentiformis and A. undulata by 15.8 and 13.0%, while lead (Pb) in the leaves decreased by 37.6 and 35.2% respectively. Despite the extremely high total heavy metals concentrations in the studied soil, plants of Atriplex were able to grow and maintain shoots metals content below the toxic level and the produced plant materials had a high nutritive value compared to the conventional forage crops. Phosphorus (P) and chloride (Cl) in the roots of Atriplex plants play important function in heavy metals phytostabilization mechanism by the two halophytes plants.  相似文献   

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