Metal Concentrations In Roots Research Articles

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.

Impact of biochar and root-induced changes on metal dynamics in the rhizosphere of Agrostis capillaris and Lupinus albus

Rhizosphere interactions are deemed to play a key role in the success of phytoremediation technologies. Here, the effects of biochar and root-induced changes in the rhizosphere of Agrostis capillaris L. and Lupinus albus L. on metal (Cd, Pb and Zn) dynamics were investigated using a biotest on a 2mm soil layer and a sequential extraction procedure (Tessier’s scheme). In the bulk soil, the application of 5% biochar significantly reduced the exchangeable pool of metals primarily due to a liming effect which subsequently promoted the metal shift into the carbonate-bound pool. However, metals were re-mobilized in the rhizosphere of both A. capillaris and L. albus due to root-induced acidification which counteracted the liming effect of biochar. As a result, the concentrations of metals in roots and shoots of both plants were not significantly reduced by the application of biochar. Although the study should be considered a worst-case scenario because experimental conditions induced the intensification of rhizosphere processes, the results highlight that changes in rhizosphere pH can impact the effectiveness of biochar to immobilize metals in soil. Biochar has thus a potential as amendment for reducing metal uptake by plants, provided the acidification of the rhizosphere is minimized.

Phragmites australis as a heavy metal bioindicator in the Anzali wetland of Iran

In this study, levels of Fe, Cu, Cd, and Ni in the sediments and organs of Phragmites australis from three different sites in the Anzali wetland were measured. Heavy metal accumulation was higher in the roots of P. australis than in the shoots and leaves. There was a significant correlation between metal concentrations in roots and sediment. This result showed that the root of P. australis can be used as bioindicator for Fe, Cu, Cd, and Ni. Metal levels in sediment were recorded higher than the interim sediment quality guideline values, and the Cd and Ni content in P. australis were higher than the unpolluted levels in plants. This indicates the necessity for continuous monitoring of the metal levels and also evaluating the hazard risk of heavy metals in aquatic organisms in the Anzali wetland.

Phytoremediation of soils co-contaminated by organic compounds and heavy metals: Bioassays with Lupinus luteus L. and associated endophytic bacteria

In the central part of the Iberian Peninsula there are old sealed landfills containing soils co-contaminated by several heavy metals (Cu, Zn, Pb, Cd, Ni, As, Cr, Fe, Al, Mn) and organic pollutants of different families (hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pesticides and other organochlorinated compounds, phenols and volatile compounds), which this work will address. We have focused on phytoremedial plants that are able to deal with this type of complex pollution, not only species that tolerate the joint effect of heavy metals in the soil, but also those that can take advantage of associated bacteria to efficiently break down organic compounds. This study was carried out with Lupinus luteus and its endophytes in two greenhouse experiments: A) growing in a substrate artificially contaminated with benzo(a)pyrene (BaP), and B) using real co-contaminated landfill soils. Endophytes of roots and shoots were isolated in both bioassays. Plant growth-promotion tests and organic pollutant tolerance and degradation tests were conducted on all strains isolated in bioassay A), and on those proving to be pure cultures from bioassay B). The selected landfill is described as are isolation and test procedures. Results indicate that plants did not show toxicity symptoms when exposed to BaP but did when grown in landfill soil. Some endophytes demonstrated plant growth-promotion capacity and tolerance to BaP and other organic compounds (diesel and PCB commercial mixtures). A few strains may even have the capacity to metabolize those organic pollutants. The overall decline in plant growth-promotion capacity in those strains isolated from the landfill soil experiment, compared with those from the bioassay with BaP, may indicate that lupin endophytes are not adapted to metal concentration in roots and shoots and fail to grow. As a result, most isolated root endophytes must have colonized root tissues from the soil. While preliminary degradation tests showed promising results (some strains exhibiting the potential to use organic pollutants as their sole source of carbon), these are not conclusive and further in-depth degradation assays need to be performed.

Phytoremediation Potential of Phragmites australis in Hokersar Wetland - A Ramsar Site of Kashmir Himalaya

Heavy metals are an important class of pollutants with both lethal and sublethal effects on organisms. Wetlands are cheap natural alternatives for removal of heavy metals from soils; however, wetland plants vary greatly in their degree of metal uptake. Hokersar wetland, a Ramsar site of Kashmir Himalaya, India is a game reserve of international importance that provides suitable habitat for resident birds and an excellent stopover point for migratory birds visiting from Palaearctic breeding grounds in Central Asia, China, N-Europe and Siberia. The toxicity of chronic dietary metal exposure in birds may have adverse reproductive effects which include decreased egg production, decreased hatchability, and increased hatchling mortality. Thus, the present study aimed to assess the heavy metal sequestration capability of one of the most common wetland plant species Phragmites australis in Hokersar wetland. The accumulation of the different elements was in order of Al > Mn > Ba > Zn > Cu > Pb > Mo > Co > Cr > Cd > Ni. Translocation factor, i.e. ratio of shoot to root metal concentration revealed that metals were largely retained in the roots of P. australis, thus reducing the supply of metals to avifauna and preventing their bio-accumulation.

Chelator-induced phytoextraction of zinc and copper by rice seedlings

Solution culture was carried to investigate capacity of synthetic aminopolycarboxylic acids (ethylenediamine tetraacetate, N-hydroxyethylenediaminetriacetic acid, and diethylenetriamine-pentaacetate) for enhancing botanical removal and transport of heavy metals (Cu and Zn) by plants. Biodegradable organic acids (citric acid, malic acid, and oxalic acid) were also selected as alternatives to compare them with synthesized chelating agents for effectiveness. Young rice seedlings (Oryza sativa L. cv. XZX 45) were grown in nutrient solutions treated with single or combined metal solutions in presence or absence of chelating compounds. Calculation by chemical equilibrium program VISUAL MINTEQ showed that different chelating compounds had various complex potential with Cu(2+) and Zn(2+) ions, in which synthetic chelators exhibited higher complexed capability than biodegradable organic acids. All applied synthetic aminopolycarboxylic acids significantly decreased removal of metal from nutrient solution (p < 0.01), while more or less effects of organic acids supplied on biosorptive potential were observed with all treatments (p > 0.05), compared with the treatment without metal ligands. Synthetic aminopolycarboxylic acids significantly decreased metal concentrations in plant materials in all treatments (p < 0.01). However, biodegradable organic acids decreased metal concentrations in roots (p < 0.01), but enhanced them in shoots (p < 0.01). Results obtained indicated that synthetic aminopolycarboxylic acids decreased uptake of metals by rice seedlings, but translocation of metals complexed within plant materials was evident. Although exogenous biodegradable organic acids showed negligible effect on botanical removal of metals, metals complexed with organic acids was more mobile than those complexed with other chelating agents. These information collected here had important implication for the use of biodegradable metal chelators in transport of essential micronutrients in plant nutrition.

Genome-Wide Identification of Transition Metal Ion Transporters in Oryza sativa

Transition metals are essential minerals required for normal growth and development of plants which are taken in correct proportions from the soil and distributed throughout the plant. The concentrations of transition metals in roots, shoots and grains were analyzed in Oryza sativa indica cultivars viz., Sona Masuri (BPT 5204), Swarna (MTU 7029) and Vijetha (MTU1001). In roots the concentration of iron was highest in Sona masuri variety, followed by manganese and zinc. In shoots and grains, iron was highest followed by zinc suggesting specific transport mechanisms in all the parts. A total of 55 genes for transition metal ion transport were identified using insilico tools of which 18 involved in zinc/iron transport, 13 for copper, 7 for manganese, 3 for cobalt, 4 for cadmium and 10 transport metal ions belonging to Nramp family. Research carried out on these metal transporters mainly provides insights into the field of rice metal biology.

Mudflat soil amendment by sewage sludge: Soil physicochemical properties, perennial ryegrass growth, and metal uptake

The fast pace of cropland loss in China is causing alarm over food security and China’s ability to remain self-reliant in crop production. Mudflats after organic amendment can be an important alternative cropland in China. Land application of sewage sludge has become a popular organic amendment to croplands in many countries. Nevertheless, the land application of sludge to mudflats has received little attention. Therefore, the objective of the present work was to investigate the impact of sewage sludge amendment (SSA) at 0, 30, 75, 150 and 300 t ha−1 rates on soil physicochemical properties, perennial ryegrass (Lolium perenne L.) growth and heavy metal accumulation in mudflat soil. The results showed that the application of sewage sludge increased organic matter (OM) content by 3.5-fold while reducing salinity by 76.3% at the 300 t ha−1 rate as compared to unamended soil. The SSA reduced pH, electric conductivity (EC) and bulk density in mudflat soil, increased porosity, cation exchange capacity (CEC) and contents of nitrogen (N), phosphorus (P), exchangeable potassium ions (K+), sodium ions (Na+), calcium ions (Ca2+) and magnesium ions (Mg2+) in comparison to unamended soil. There were 98.0, 146.6, 291.4 and 429.2% increases in fresh weight and 92.5, 132.4, 258.6 and 418.9% increases in dry weight of perennial ryegrass at 30, 75, 150, and 300 t ha−1, respectively, relative to unamended soil. The SSA increased metal concentrations of aboveground and root parts of perennial ryegrass (p < 0.05). The metal concentrations in perennial ryegrass were Zn > Cr > Mn > Cu > Cd > Ni, and the metal concentrations in roots were significantly higher than aboveground parts. The metal accumulation in perennial ryegrass correlated positively with sludge application rates and available metal concentrations in mudflat soil. Land application of sewage sludge was proved to be an effective soil amendment that improved soil fertility and promoted perennial ryegrass growth in mudflat soil. However, heavy metal accumulation in plants may cause food safety concern.

Fine Root Branch Orders Contribute Differentially to Uptake, Allocation, and Return of Potentially Toxic Metals

Growing evidence has revealed high heterogeneity of fine root networks in both structure and function, with different root orders corporately maintaining trees' physiological activities. However, little information is available on how fine root heterogeneity of trees responds to environmental stresses. We examined concentrations of seven potentially toxic metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) within fine root networks and their correlations with root morphological and macro-elemental traits in six Chinese subtropical trees. The contributions of different orders of roots to fine-root metal storage and return were also estimated. Results showed no consistent pattern for the correlation among different metal concentration against root traits. Unlike root metal concentration that generally decreased with root order, root metal storage was commonly lowest in middle root orders. Root senescence was at least comparable to leaf senescence contributing to metal removal. Although the first-order roots constituted 7.2-22.3% of total fine root biomass, they disproportionately contributed to most of metal return fluxes via root senescence. The two distinct root functional modules contributed differentially to metal uptake, allocation, and return, with defensive (lower-order) roots effectively stabilizing and removing toxic metals and bulk buffering (higher-order) roots possessing a persistent but diluted metal pool. Our results suggest a strong association of physiological functions of metal detoxification and metal homeostasis with the structural heterogeneity in fine root architecture.

Tanacetum vulgare as a Bioindicator of Trace-Metal Contamination: A Study of a Naturally Colonized Open-Pit Lignite Mine

We investigated the possibility of use of Tanacetum vulgare (tansy) as an ecological indicator of metal concentration in a naturally colonized open-pit lignite mine in Bełchatów (Poland). Tanacetum vulgare is the only species growing abundantly and spontaneously in the lignite mine waste dumps. Metal concentrations in roots, stems, leaves, flowers, and soil were measured in dump sites differing in type and time of reclamation and therefore differing in pollution levels. Tanacetum vulgare appeared to be an accumulator of chromium and iron in roots, whereas highest concentrations of manganese and zinc were found in leaves. A high bioaccumulation factor for cadmium (Cd) was observed in dumps and control sites, indicating that even small amounts of Cd in the environment may result in significant uptake by the plant. The lowest concentrations of metals were found in plants from sites situated on dumps reclaimed with argillaceous limestone.

Phytostabilization of metals in mine soils using Brassica juncea in combination with organic amendments

The high metal bioavailability and the poor conditions of mine soils yield a low plant biomass, limiting the application of phytoremediation techniques. A greenhouse experiment was performed to evaluate the effects of organic amendments on metal stabilization and the potential of Brassica juncea L. for phytostabilization in mine soils. Plants were grown in pots filled with soils collected from two mine sites located in Central Spain mixed with 0, 30 and 60 t ha−1 of pine bark compost and horse- and sheep-manure compost. Plant biomass and metal concentrations in roots and shoots were measured. Metal bioavailability was assessed using a rhizosphere-based method (rhizo), which consists of a mixture of low-molecular-weight organic acids to simulate root exudates. Manure reduced metal concentrations in shoots (10–50 % reduction of Cu and 40–80 % of Zn in comparison with non-amended soils), bioconcentration factor (10–50 % of Cu and 40–80 % of Zn) and metal bioavailability in soil (40–50 % of Cu and 10–30 % of Zn) due to the high pH and the contribution of organic matter. Manure improved soil fertility and was also able to increase plant biomass (5–20 times in shoots and 3–30 times in roots), which resulted in a greater amount of metals removed from soil and accumulated in roots (increase of 2–7 times of Cu and Zn). Plants grown in pine bark treatments and in non-amended soils showed a limited biomass and high metal concentrations in shoots. The addition of manure could be effective for the stabilization of metals and for enhancing the phytostabilization ability of B. juncea in mine soils. In this study, this species resulted to be a potential candidate for phytostabilization in combination with manure, differing from previous results, in which B. juncea had been recognized as a phytoextraction plant.

Use of Drinking Water Treatment Residuals in Reducing Bioavailability of Metals in Biosolid-Amended Alkaline Soils

This greenhouse study evaluated the use of drinking-water-treatment residuals (WTRs) to reduce the bioavailability of metals in the biosolid-amended agricultural alkaline soils. Results showed that increasing the application rate of biosolids increased the accumulation of lead (Pb), nickel (Ni), copper (Cu), and cadmium (Cd) in corn (Zea mays cv. single hybride 10), with greater metal concentrations in roots than in shoots. However, the addition of WTRs (1–4%, w/w) to the soil amended with 3% biosolids significantly (P < 0.05) decreased the concentrations of soil diethylenetriaminepentaacetic acid (DTPA)–extractable metals. The accumulation of Pb, Ni, Cu, and Cd in corn significantly correlated with the DTPA-extractable metal concentrations in the soils. Plant metal concentrations were significantly affected by the soil type, application rates of biosolids and WTRs, and the ratio of WTRs to biosolids in the soils. The 1:1 application ratio of WTRs to biosolids at the 3% application rate effectively reduced the accumulation of metals in corn tissues.

Characteristics of heavy metal accumulation on fly ash- and sewage sludge-amended calcific soil

Land disposal of fly ash (FA) and sewage sludge (SS) is a major problem due largely to their potentially harmful constituents. In this paper, a potting experiment was performed to evaluate the effects on the plant growth and to discuss in particular the potential hazard to soils and plants according to the characteristics of heavy metal accumulation and migration when FA and SS are used as the amendments of calcific soil in a limestone mining area. The results showed that the application of FA-SS mixture is capable of accelerating the growth of plants and improving the biomass production at either 1:1 or 1:2 FA-SS mixture: soil (w/w). The highest yields were obtained at 1:1 (w/w) mixing ratio. When compared with the Element Background Values of Soils in China, the analysis on heavy metals indicated that the contents of Pb, Cr, Hg, Cd, As, Ni, Cu and Zn in the amended soils came up to the second-class environmental quality standards, only Hg and Cd showed significant accumulation. At the same time, though the metal concentrations in roots were higher than those for the control, the concentrations except Cu, Zn in shoots were lower. And all the heavy metal contents in the plants were substantially lower than the toxicity limits. The results indicated that the combined use of FA and SS at a rational rate of application should pose no danger to both soil and food chain based on the characteristics of the FS and SS, heavy metals and calcific soil.

Functioning and toxicity of artificial soil mixtures with metal-bearing sewage sludge

Various artificial soil mixtures were prepared by mixing two different toxic metals containing sewage sludge from Ljubljana and Maribor wastewater treatment plants with natural mineral soil. The plots with mixtures were exposed to field environmental conditions for a period of 1 year, after which we assessed soil toxicity (germination test with Lactuca sativa), potential metal phyto-accessibility (diethylenetriamine pentaacetic acid – DTPA extraction test), soil functioning (by soil enzymes activity) and conducted a field growth test with Lollium perenne L. as a metal bio-indicator plant. The metal phyto-accessibility extraction test (DTPA) showed lower values than the metal accumulation test with L. perenne L., which also showed higher metal concentrations in roots compared to leaves. With the exception of the mixture containing 30% (w/w) of sludge from the Ljubljana wastewater treatment plant, all mixtures containing more than 20% of sludge negatively affected root elongation of L. sativa seeds, indicating an increase in artificial soils toxicity. Increasing the ratio of sludge from the Ljubljana plant increased dehydrogenase and decreased phosphomonoesterase, while the addition of sludge from the Maribor plant increased phosphomonoesterase activity. Overall, the effect of sludge addition on artificial soil properties, toxicity and functioning not only depended on dosage but was also sensitive to the source and pre-treatment of the sewage sludge.

Combined mild soil washing and compost-assisted phytoremediation in treatment of silt loams contaminated with copper, nickel, and chromium

A new soil remediation option, combining the soil washing process using pure water followed by the compost-assisted phytoextraction, is evaluated using silt loams contaminated with plating wastewater containing Cu, Ni, and Cr. Plants utilized in this study are the rapeseeds, sunflowers, tomatoes, and soapworts. Phytoextraction operation was carried out in pot experiments over a period of 4 months. Metal concentrations in roots and shoots of plants were analyzed upon completion of each pot experiment. Hypothesis testing was employed in assessing the significance of difference in the experimental data. Results indicated that the rapeseed, a hyperaccumulator, is most effective in extracting metals from the compost-amended silt loams. The fast-growing sunflowers and tomatoes are comparable to rapeseeds in accumulating metals despite their relatively low metal concentrations in tissues. Bioaccumulation coefficients obtained for all plants are less than one, indicating that phytostabilization rather than phytoextraction is the dominant mechanism at this simulated final-phase condition.

Neutron activation analysis of wheat samples

The deficiency of essential micronutrients and excess of toxic metals in cereals, an important food items for human nutrition, can cause public health risk. Therefore, before their consumption and adoption of soil supplementation, concentrations of essential micronutrients and metals in cereals should be monitored. This study collected soil and two varieties of wheat samples-Triticum aestivum L. (Jordão/bread wheat), and Triticum durum L. (Marialva/durum wheat) from Elvas area, Portugal and analyzed concentrations of As, Cr, Co, Fe, K, Na, Rb and Zn using Instrumental Neutron Activation Analysis (INAA) to focus on the risk of adverse public health issues. The low variability and moderate concentrations of metals in soils indicated a lower significant effect of environmental input on metal concentrations in agricultural soils. The Cr and Fe concentrations in soils that ranged from 93-117 and 26,400-31,300mg/kg, respectively, were relatively high, but Zn concentration was very low (below detection limit <22mg/kg) indicating that soils should be supplemented with Zn during cultivation. The concentrations of metals in roots and straw of both varieties of wheat decreased in the order of K>Fe>Na>Zn>Cr>Rb>As>Co. Concentrations of As, Co and Cr in root, straw and spike of both varieties were higher than the permissible limits with exception of a few samples. The concentrations of Zn in root, straw and spike were relatively low (4-30mg/kg) indicating the deficiency of an essential micronutrient Zn in wheat cultivated in Portugal. The elemental transfer from soil to plant decreases with increasing growth of the plant. The concentrations of various metals in different parts of wheat followed the order: Root>Straw>Spike. A few root, straw and spike samples showed enrichment of metals, but the majority of the samples showed no enrichment. Potassium is enriched in all samples of root, straw and spike for both varieties of wheat. Relatively to the seed used for cultivation, Jordão presented higher transfer coefficients than Marialva, in particular for Co, Fe, and Na. The Jordão and Marialva cultivars accumulated not statistically significant different concentrations of different metals. The advantages of using INAA are the multielementality, low detection limits and use of solid samples (no need of digestion).

ACCUMULATION OF HEAVY METALS PB, CU, AND ZN IN THE MANGROVE FOREST OF MUARA ANGKE, NORTH JAKARTA

In this study, the concentrations of three kinds of heavy metals, namely Pb, Zn, and Cu from 3 species of mangrove that grow in Muara Angke were measured and analyzed. Our result showed that substrate of mangrove ecosystem in Muara Angke was dominated by clay (30.5% - 62.4%), silt (21.7% -35.6%), and sand (2% -39.5%). The heavy metals accumulation in roots is higher than in sediment, water and leaves with concentration of Zn as the highest. Bioconcentration Factor (BCF; content ratio of heavy metal concentrations in roots or leaves and sediment) and Translocation Factor (TF; ratio of heavy metal concentrations in leaves and roots) of non-essential heavy metals (Pb) is higher in leaves than in roots, but for essential heavy metals (Zn and Cu), the BCF and TF was higher in roots than in leaves. TF values for heavy metals Pb, Cu, and Zn were 0.98-2.59, 0.17-0.51, and 0.52-0.86, respectively. The values of root BCF of those three heavy metals were 0.71-3.17, 0.27-0.74, and 0.95-1.53, while the values of leaf BCF were 1.84-3.45, 0.07-0.34, and 0.72-1.19, respectively. Furthermore, by calculating the phytoremediation (FTD), i.e. the difference between BCF and TF, it is obtained that Sonneratia caseolaris and Avicennia marina can be used in phytoremidiation, with leaves and roots FTD of 1.93 and 2.09, respectively for Sonneratia caseolaris and 1.93 and 1.98 for Avicennia marina.Keywords: heavy metals, mangroves, phytoremidiation, Muara Angke, bioconcentration factor, translocation factor

ACCUMULATION OF HEAVY METALS PB, CU, AND ZN IN THE MANGROVE FOREST OF MUARA ANGKE, NORTH JAKARTA

&lt;p&gt;In this study, the concentrations of three kinds of heavy metals, namely Pb, Zn, and Cu from 3 species of mangrove that grow in Muara Angke were measured and analyzed. Our result showed that substrate of mangrove ecosystem in Muara Angke was dominated by clay (30.5% - 62.4%), silt (21.7% -35.6%), and sand (2% -39.5%). The heavy metals accumulation in roots is higher than in sediment, water and leaves with concentration of Zn as the highest. Bioconcentration Factor (BCF; content ratio of heavy metal concentrations in roots or leaves and sediment) and Translocation Factor (TF; ratio of heavy metal concentrations in leaves and roots) of non-essential heavy metals (Pb) is higher in leaves than in roots, but for essential heavy metals (Zn and Cu), the BCF and TF was higher in roots than in leaves. TF values for heavy metals Pb, Cu, and Zn were 0.98-2.59, 0.17-0.51, and 0.52-0.86, respectively. The values of root BCF of those three heavy metals were 0.71-3.17, 0.27-0.74, and 0.95-1.53, while the values of leaf BCF were 1.84-3.45, 0.07-0.34, and 0.72-1.19, respectively. Furthermore, by calculating the phytoremediation (FTD), i.e. the difference between BCF and TF, it is obtained that Sonneratia caseolaris and Avicennia marina can be used in phytoremidiation, with leaves and roots FTD of 1.93 and 2.09, respectively for Sonneratia caseolaris and 1.93 and 1.98 for Avicennia marina.&lt;/p&gt;&lt;p&gt;Keywords: heavy metals, mangroves, phytoremidiation, Muara Angke, bioconcentration factor, translocation factor&lt;/p&gt;

Mycorrhizo-Remediation of Lead/Zinc Mine Tailings Using Vetiver: A Field Study

A field study of Pb/Zn mine tailings was conducted to assess the influence of AM fungi and refuse compost on phytoremediation using vetiver grass slips. Our investigation revealed that vetiver could thrive on Pb/Zn mine tailings. The addition of refuse compost resulted in biomass that was more than 3-times higher when compared with the control, and were mainly attributed to an improvement of soil properties, as well as better nutrient supply than untreated control. AMF inoculation also significantly increased the dry matter of vetiver by a rate of 8.1–13.8%. It was observed that concentrations of N and P in the shoots were significantly higher in mycorrhizal treatments than those without AMF inoculation. However, AMF inoculation significantly decreased the metal concentrations in root, but not in shoot. Based on the results, it seems clear that AMF can play an essential role in the phytostabilization of metal contaminated soils.

Growth changes and tissues anatomical characteristics of giant reed (Arundo donax L.) in soil contaminated with arsenic, cadmium and lead

A greenhouse experiment was conducted to elucidate the growth changes and tissues anatomical characteristics of giant reed (Arundo donax L.), a perennial rhizomatous grass, which was cultivated for 70 d in soils contaminated with As, Cd and Pb. The results show that giant reed rapidly grows with big biomass of shoots in contaminated soil, possessing strong metal-tolerance with limited metal translocation from roots to shoots. When As, Cd and Pb concentrations in the soil are less than 254, 76.1 and 1 552 mg/kg, respectively, plant height and dried biomass are slightly reduced, the accumulation of As, Cd and Pb in shoots of giant reed is low while metal concentration in roots is high, and the anatomical characteristics of stem tissues are thick and homogeneous according to SEM images. However, plant height and dried biomass are significantly reduced and metal concentration in plant shoots and roots are significantly increased (P<0.05), the stems images become heterogeneous and the secretion in vascular bundles increases significantly when As, Cd and Pb concentrations in the soil exceed 334, 101 and 2 052 mg/kg, respectively. The giant reed is a promising, naturally occurring plant with strong metal-tolerance, which can be cultivated in soils contaminated with multiple metals for ecoremediation purposes.