Heavy Metal-contaminated Sites Research Articles

Soil heterogeneity influence on the distribution of heavy metals in soil during acid rain infiltration: Experimental and numerical modeling

Acid rain is a global environmental problem that mobilizes heavy metals in soils, while the distribution and geochemical fraction of heavy metals during acid rain infiltration in heterogeneous soils are still unclear. In this study, we performed column experiments to investigate the distribution and geochemical fraction of Cu, Pb, Ni and Cd in heterogeneously layered soils during continuous acid rain infiltration. Chloride ion used as a conservative tracer was found to be uniformly distributed during acid rain infiltration, showing insignificant preferential flow effects in the column. In contrast, however, the distribution of heavy metals was highly non-uniform, especially in the silty soil at the lower part of the column, indicating a heterogeneous distribution of adsorption capacity. In addition, in the control experiments with neutral rain infiltration, uniform distribution of heavy metals was observed, indicating that the heterogeneous distribution of adsorption coefficient during acid rain infiltration was mainly caused by different pH buffering capacities. A numerical model considering water flow and solute transport was developed, where the average water-solid distribution coefficient (Kd) in Layer 2 was only 1.5–12.5% of that in Layer 1 during acid rain infiltration. The model could predict the variation of heavy metal concentrations in soil with the majority of error less than 35%, confirming that different Kd induced the heterogeneous distribution of heavy metals. In addition, the geochemical fraction of heavy metals in the upper coarse sand layer remained stable, while the acid-extractable fractions in the lower loam and silt loam layer gradually increased. Our findings suggest that soil heterogeneity, especially chemical heterogeneity affected by rainfall acidity, has an important influence on the infiltration, migration and geochemical fraction of heavy metals in soils. This study could help guide the risk assessment of heavy metal-contaminated sites that were polluted by acid rain or landfill leachate.

Enhancement of humic acid on plant growth in a Cd-contaminated matrix: performance, kinetics, and mechanism.

Phytoremediation of heavy metal-contaminated sites has been widely used. Nonetheless, the destruction of chloroplasts and plant growth enzymes by heavy metals leads to a low germination rate and high mortality of plants. To address these issues, an experiment was conducted in which plants were grown with (SHC) and without humic acid (SC) in actual Cd-contaminated soil from the site of an industrial pollution source. The results showed that the average germination rates of SC and SHC samples were 94.17% and 98.33%, respectively, and the plant heights were approximately 5 and 7cm after 42days of planting, respectively. It was discovered that humic acid (HA) enhanced plant growth by increasing urease and invertase content of the soil. The Shannon index and Venn diagram revealed that SHC had the richer population diversity. High-throughput analysis demonstrated that HA increased the content of plant growth-promoting bacteria in the soil from 5.01 to 34.27%. The experimental results revealed that HA increased microbial activity and diversity, thereby providing a favorable environment for plants to thrive. This study develops an effective method to enhance the phytoremediation performance of heavy metal-contaminated soils.

Speciation Distribution and Influencing Factors of Heavy Metals in Rhizosphere Soil of Miscanthus Floridulus in the Tailing Reservoir Area of Dabaoshan Iron Polymetallic Mine in Northern Guangdong

Through field investigation and experimental analysis, the forms, contents and distribution of heavy metals (Zn, Pb, Cu, Cd, Ni, Cr) in rhizosphere and non-rhizosphere soils of Miscanthus floridulus growing everywhere in Tielongwei mine pond (sample plot 1), Caoduikeng tailings pond (sample plot 2), Donghua tailings pond (sample plot 3) and Small tailings pond (sample plot 4) in Dabaoshan, Guangdong Province were studied. The results showed that the main forms and distributions of heavy metals in rhizosphere and non-rhizosphere soils are basically the same, which shows that the mineral content accounts for most of the total amount of heavy metals, while the exchange content is low. Compared with non-rhizosphere soil, the proportion of exchangeable and organic heavy metals in rhizosphere soil increased significantly, in which the proportion of organic-bound Cu increased by 53.25%, the proportion of organic-bound Cd and Pb increased by more than 17%, and the proportion of Zn increased by 5.67%. At the same time, the contents of carbonate-bound and iron manganese oxide-bound decreased. Statistical analyses showed that the morphological distribution of Zn, Pb, Cu, Cd, Ni and Cr in rhizosphere soil was closely related to soil pH value, organic matter content, plant growth and other factors. The results of this study provided a basis for the restoration of heavy metal-contaminated sites by Miscanthus.

Remediation of copper-contaminated soils using Tagetes patula L., earthworms and arbuscular mycorrhizal fungi

Arbuscular mycorrhizal fungi (AMF) and earthworms have potential uses in the bioremediation of contaminated soils. In recent years, heavy metal-contaminated sites have been remediated by adding plants and AMF or earthworms to the soil. However, there are few studies on remediation using combinations of plants, animals, and microbes, especially for the remediation of Cu-contaminated soil. The present study investigated the separate and combined effects of AMF and earthworms on Cu-contaminated soil in which Tagetes patula L. was grown. The results show that the combined application of AMF and earthworms markedly increased the biomass of plant shoots and roots by more than 100%. It also increased Cu extraction by T. patula by 270%. The combined treatment was effective in increasing the CEC, contents of OM, and available Cu, P and K, but reduced the soil pH. Furthermore, the combined treatment significantly increased the abundance and diversity of the soil microbial community. In particular, the abundances of the bacteria Bacteroides, Proteobacteria, and Actinobacteria were increased, with the genera Flavobacterium, Pedobacter, Algoriphagus, Gaetbulibacter, Pseudomonas, Luteimonas, and Arthrobacter dominating. Meanwhile, the abundance of the fungus Zygomycota was increased, with Mortierella dominating. Moreover, inoculation with earthworms greatly improved the structure of the soil microbial community.

Remediation of zinc-contaminated groundwater by iron oxide in situ adsorption barriers – From lab to the field

Heavy metals such as zinc cannot be degraded by microorganisms and form long contaminant plumes in groundwater. Conventional methods for remediating heavy metal-contaminated sites are for example excavation and pump-and-treat, which is expensive and requires very long operation times. This induced interest in new technologies such as in situ adsorption barriers for immobilization of heavy metal contamination. In this study, we present steps and criteria from laboratory tests to field studies, which are necessary for a successful implementation of an in situ adsorption barrier for immobilizing zinc. Groundwater and sediment samples from a contaminated site were brought to the lab, where the adsorption of zinc to Goethite nanoparticles was studied in batch and in flow-through systems mimicking field conditions. The Goethite nanoparticles revealed an in situ adsorption capacity of approximately 23 mg Zn per g Goethite. Transport experiments in sediment columns indicated an expected radius of influence of at least 2.8 m for the injection of Goethite nanoparticles. These findings were validated in a pilot-scale field study, where an in situ adsorption barrier of ca. 11 m × 6 m × 4 m was implemented in a zinc-contaminated aquifer. The injected nanoparticles were irreversibly deposited at the desired location within <24 h, and were not dislocated with the groundwater flow. Despite a constantly increasing inflow of zinc to the barrier and the short contact time between Goethite and zinc in the barrier, the dissolved zinc was effectively immobilized for ca. 90 days. Then, the zinc concentrations increased slowly downstream of the barrier, but the barrier still retained most of the zinc from the inflowing groundwater. The study demonstrated the applicability of Goethite nanoparticles to immobilize heavy metals in situ and highlights the criteria for upscaling laboratory-based determinants to field-scale.

The Different Faces of Arabidopsis arenosa-A Plant Species for a Special Purpose.

The following review article collects information on the plant species Arabidopsis arenosa. Thus far, A. arenosa has been known as a model species for autotetraploidy studies because, apart from diploid individuals, there are also tetraploid populations, which is a unique feature of this Arabidopsis species. In addition, A arenosa has often been reported in heavy metal-contaminated sites, where it occurs together with a closely related species A. halleri, a model plant hyperaccumulator of Cd and Zn. Recent studies have shown that several populations of A. arenosa also exhibit Cd and Zn hyperaccumulation. However, it is assumed that the mechanism of hyperaccumulation differs between these two Arabidopsis species. Nevertheless, this phenomenon is still not fully understood, and thorough research is needed. In this paper, we summarize the current state of knowledge regarding research on A. arenosa.

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.

Draft Genome Sequence of Bacillus sp. Strain EB106-08-02-XG196, Isolated from High-Nitrate-Contaminated Sediment.

Bacillus sp. strain EB106-08-02-XG196 was isolated from a high-nitrate- and heavy metal-contaminated site at the Oak Ridge Reservation in Tennessee. We report the draft genome sequence of this strain to provide insights into the genomic basis for surviving in this unique environment.

Fungal Endophytes for Grass Based Bioremediation: An Endophytic Consortium Isolated from Agrostis stolonifera Stimulates the Growth of Festuca arundinacea in Lead Contaminated Soil.

Bioremediation is an ecologically-friendly approach for the restoration of heavy metal-contaminated sites and can exploit environmental microorganisms such as bacteria and fungi. These microorganisms are capable of removing and/or deactivating pollutants from contaminated substrates through biological and chemical reactions. Moreover, they interact with the natural flora, protecting and stimulating plant growth in these harsh conditions. In this study, we isolated a group of endophytic fungi from Agrostis stolonifera grasses growing on toxic waste from an abandoned lead mine (up to 47,990 Pb mg/kg) and identified them using DNA sequencing (nrITS barcoding). The endophytes were then tested as a consortium of eight strains in a growth chamber experiment in association with the grass Festuca arundinacea at increasing concentrations of lead in the soil to investigate how they influenced several growth parameters. As a general trend, plants treated with endophytes performed better compared to the controls at each concentration of heavy metal, with significant improvements in growth recorded at the highest concentration of lead (800 galena mg/kg). Indeed, this set of plants germinated and tillered significantly earlier compared to the control, with greater production of foliar fresh and dry biomass. Compared with the control, endophyte treated plants germinated more than 1-day earlier and produced 35.91% more plant tillers at 35 days-after-sowing. Our results demonstrate the potential of these fungal endophytes used in a consortium for establishing grassy plant species on lead contaminated soils, which may result in practical applications for heavy metal bioremediation.

Comparative Genomics of Microbacterium Species to Reveal Diversity, Potential for Secondary Metabolites and Heavy Metal Resistance

Microbacterium species have been isolated from a wide range of hosts and environments, including heavy metal-contaminated sites. Here, we present a comprehensive analysis on the phylogenetic distribution and the genetic potential of 70 Microbacterium belonging to 20 different species isolated from heavy metal-contaminated and non-contaminated sites with particular attention to secondary metabolites gene clusters. The analyzed Microbacterium species are divided in three main functional clades. They share a small core genome (331 gene families covering basic functions) pointing to high genetic diversity. The most common secondary metabolite gene clusters encode pathways for the production of terpenoids, type III polyketide synthases and non-ribosomal peptide synthetases, potentially responsible of the synthesis of siderophore-like compounds. In vitro tests showed that many Microbacterium strains produce siderophores, ACC deaminase, auxins (IAA) and are able to solubilize phosphate. Microbacterium isolates from heavy metal contaminated sites are on average more resistant to heavy metals and harbor more genes related to metal homeostasis (e.g., metalloregulators). On the other hand, the ability to increase the metal mobility in a contaminated soil through the secretion of specific molecules seems to be widespread among all. Despite the widespread capacity of strains to mobilize several metals, plants inoculated with selected Microbacterium isolates showed only slightly increased iron concentrations, whereas concentrations of zinc, cadmium and lead were decreased.

Lead and cadmium-resistant bacterial species isolated from heavy metal-contaminated soils show plant growth-promoting traits.

Application of metal-resistant rhizobacteria is a promising approach for detoxification and bioremediation of contaminated soils. In order to isolate, identify, and characterize lead and cadmium-resistant bacteria, nearly 30 soil samples were collected from heavy metal-contaminated sites, and five resistant bacterial strains were isolated and identified based on their cultural, physiological, biochemical, and molecular characteristics as Enterobacter cloacae, Enterobacter kobei, Bacillus cereus, Rhizobium pusense, and Agrobacterium tumefaciens. The nucleotide information of these strains is available in GenBank under the accession numbers of MH327251, MH327252, MH327253, MH327254, and MK123361, respectively. The minimum inhibitory concentrations (MICs) against lead and cadmium differed for each isolate and the isolates showed higher MIC against lead (3500μgml-1) than cadmium (100μgml-1). Assessment of the heavy metal degradation capacity of the species showed 10-60% and 5-40% reduction in concentrations of lead and cadmium, respectively. The highest ability for P-solubilization was measured for the R. pusense, A. tumefaciens, and B. cereus species, while the R. pusense and B. cereus species had the capability to solubilize potassium. The studied species also had the ability to produce indole acetic acid (IAA) and/or hydrogen cyanide production (HCN). Inoculation of ornamental cabbage cultivated in a heavy metal-contaminated soil with the isolated species significantly increased biomass and Pb and Cd uptake of the plant. With respect to plant growth promoting and heavy metal-resistant traits of the studied species, it is concluded that these species can have great significance in bioremediation and management of environmental pollution.

Assessment of strength and leaching characteristics of heavy metal-contaminated soils solidified/stabilized by cement/fly ash.

Solidification/stabilization technique has been widely adopted to remediate the heavy metal-contaminated sites. In the present work, the strength and leaching characteristics of the contaminated soils solidified/stabilized by cement/fly ash were systemically investigated. Electrical resistivity was also measured to establish empirical relationships for assessment of remediation efficacy. Tests results showed that the unconfined compressive strength increased and the leached ion concentration decreased with increasing curing time. In contrast, the unconfined compressive strength decreased and the leached ion concentration increased with increasing initial heavy metal ion concentration in the specimen. For the strength characteristic, the most notable detrimental effect was induced by Cr3+ and the least was induced by Pb2+. For the leaching characteristic, the trend was reversed. The electrical resistivity of the tested specimen increased significantly with increasing curing time and with decreasing initial ion concentration. The electrical resistivity of the Pb-contaminated specimen was higher than that of the Zn-contaminated specimen, which in turn was higher than that of the Cr-contaminated specimen. Empirical relationships between the strength, leaching characteristic, and electrical resistivity were established, which could be adopted to assess the remediation efficacy of heavy metal-contaminated soil solidified/stabilized by cement/fly ash.

Physiological, biochemical and proteomic insight into integrated strategies of an endophytic bacterium Burkholderia cenocepacia strain YG-3 response to cadmium stress.

An endophytic bacterium YG-3 with high cadmium (Cd) resistance was isolated from poplar grown in a composite mine tailing. It was identified as Burkholderia cenocepacia based on genomic, physiological and biochemical analyses. The Cd removal rate by YG-3 could reach about 60.0% in Cd aqueous solution with high concentrations of both 100 and 500 mg L-1. Meanwhile, various absorption and adsorption strategies were found in the two different Cd concentrations. The global resistance mechanisms of YG-3 were investigated in several levels, i.e., physiological observation, such as scanning electron microscopy and transmission electron microscopy; biochemical detection for active compound production and infrared spectroscopy; label-free quantitative proteomic profile analysis. The results indicated that YG-3 possesses a complex mechanism to adapt to Cd stress: (1) binding of Cd to prevent it from entering the cell by the cell wall components, as well as secreted siderophores and exopolysaccharides; (2) intracellular sequestration of Cd by metalloproteins; (3) excretion of Cd from the cell by efflux pumps; (4) alleviation of Cd toxicity by antioxidants. Our results demonstrate that endophyte YG-3 is well adjusted to largely remove Cd and has potential to cooperate with its host to improve phytoremediation efficiency in heavy metal-contaminated sites.

Evaluation of Phytoremediation Potential of Castor Cultivars for Heavy Metals from Soil

ABSTRACT: Phytoremediation is a useful tool to restore heavy metals contaminated soils. This study was carried out to test two castor (Ricinus communis) cultivars [Local and DS-30] for phytoextraction of heavy metals from the soil spiked by known concentrations of seven metals (Cu, Cr, Fe, Mn, Ni, Pb and Zn). A pot experiment was laid out by using a completely randomized design. Soil and plant samples were analyzed at 100 days after planting. The data on heavy metal uptake by plant tissues (roots, leaves and shoots) of the two castor cultivars suggested that a considerable amount of metals (Fe = 27.18 mg L-1; Cu = 5.06 mg L-1; Cr = 2.95 mg L-1; Mn = 0.22 mg L-1; Ni = 4.66 mg L-1; Pb = 3.33 mg L-1; Zn = 15.04 mg L-1) was accumulated in the plant biomass. The soil heavy metal content at the end of experiment significantly decreased with both cultivars, resulting in improved soil quality. Therefore, it is concluded that both castor cultivars, Local and DS-30, can be used for phytoremediation of heavy metal-contaminated sites.

Phytoremediation of Heavy Metal-Contaminated Sites: Eco-environmental Concerns, Field Studies, Sustainability Issues, and Future Prospects.

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders, and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physicochemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metal-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches; evaluates their efficacy to remove toxic metals from our natural environment; explores current scientific progresses, field experiences, and sustainability issues; and revises world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in the twenty-first century.

Rhizoglomus venetianum, a new arbuscular mycorrhizal fungal species from a heavy metal-contaminated site, downtown Venice in Italy

Rhizoglomus venetianum, a new arbuscular mycorrhizal fungal species, has been isolated and propagated from a heavy metal-contaminated site in Sacca San Biagio island, downtown Venice, Italy. Interestingly, under the high levels of heavy metals occurring in the site, the new fungus was able to grow only intraradically. In greenhouse trap and single species cultures under low heavy metal levels, the fungus produced innumerous spores, clusters, and sporocarps extraradically, which were formed terminally on subtending hyphae either singly, in small spore clusters, or, preferably, in loose to compact non-organized sporocarps up to 2500 × 2000 × 2000 μm. Spores are golden-yellow to bright yellow brown, globose to subglobose to rarely oblong, 75–145 × 72–140 μm in diameter, and have four spore wall layers. Morphologically, the new fungus is similar to R. intraradices, and phylogenetically, it forms a monophyletic clade next to R. irregulare, which generally forms irregular spores and lacks, like R. intraradices, the flexible innermost wall layer beneath the structural/persistent third wall layer. A key for the species identification is presented comprising all 18 Rhizoglomus species, so far described or newly combined.

Endophytic fungal community of Dysphania ambrosioides from two heavy metal-contaminated sites: evaluated by culture-dependent and culture-independent approaches.

SummaryEndophytic fungal communities of Dysphania ambrosioides, a hyperaccumulator growing at two Pb‐Zn‐contaminated sites, were investigated through culture‐dependent and culture‐independent approaches. A total of 237 culturable endophytic fungi (EF) were isolated from 368 tissue (shoot and roots) segments, and the colonization rate (CR) ranged from 9.64% to 65.98%. The isolates were identified to 43 taxa based on morphological characteristics and rDNA ITS sequence analysis. Among them, 13 taxa (30.23%) were common in plant tissues from both sites; however, dominant EF were dissimilar. In culture‐dependent study, 1989 OTUs were obtained through Illumina Miseq sequencing, and dominant EF were almost same in plant tissues from both sites. However, some culturable EF were not observed in total endophytic communities. We suggest that combination of both culture‐dependent and culture‐independent methods will provide more chances for the precise estimation of endophytic fungal community than using either of them. The tissue had more influence on the culturable fungal community structure, whereas the location had more influence on the total fungal community structure (including culturable and unculturable). Both culture‐dependent and culture‐independent studies illustrated that endophytic fungal communities of D. ambrosioides varied across the sites, which suggested that HM concentration of the soil may have some influence on endophytic fungal diversity.

Application of portable X-ray fluorescence spectrometry in environmental investigation of heavy metal-contaminated sites and comparison with laboratory analysis

In this study, portable X-ray fluorescence spectrometry (pXRF) was used to measure the heavy metal contents of As, Cu, Cr, Ni, Pb and Zn in the soils of heavy metal-contaminated sites. The precision, accuracy and system errors of pXRF were evaluated and compared with traditional laboratory methods to examine the suitability of in situ pXRF. The results show that the pXRF analysis achieved satisfactory accuracy and precision in measuring As, Cr, Cu, Ni, Pb, and Zn in soils, and meets the requirements of the relevant detection technology specifications. For the certified reference soil samples, the pXRF results of As, Cr, Cu, Ni, Pb, and Zn show good linear relationships and coefficients of determination with the values measured using the reference analysis methods; with the exception of Ni, all the measured values were within the 95% confidence level. In the soil samples, the coefficients of determination between Cu, Zn, Pb, and Ni concentrations measured laboratory pXRF and the values measured with laboratory analysis all reach 0.9, showing a good linear relationship; however, there were large deviations between methods for Cr and As. This study provides reference data and scientific support for rapid detection of heavy metals in soils using pXRF in site investigation, which can better guide the practical application of pXRF.

Available Approaches of Remediation and Stabilisation of Metal Contamination in Soil: A Review

Anthropogenic activities, such as mining of natural resources, manufac-turing industries, modern agricultural practices and energy production have resulted in the release of heavy metals with resultant harmful im-pacts in some natural environments. Toxic heavy metals are harmful to living organisms even at low concentrations. Therefore, heavy metal contaminated sites should be remediated as heavy metals do not decompose into less harmful substances and are retained in the soil. Conventional methods are used for remediation of heavy metal contaminated soils such as heavy metal extraction, immobilization and removal of soils to landfill produce large quantities of toxic products including insoluble hydroxides and are rarely cost effective. The advent of bioremediation technologies like biosparging, bioventing and bioaugmentation has provided an alternative to conventional methods for remediating heavy metal contaminated soils. A subset of bacteria found in the rhizosphere has been found to increase the tolerance of plants to heavy metals in soil. These bacteria commonly known as plant growth promoting rhizobacteria or Plant Growth Promoting Rhizobacteria (PGPR) are showing promise as a bioremediation technique for the stabilisation and remediation of heavy metal contami-nated sites. PGPR can improve plant growth via a variety of mechanism including fixing atmospheric N to improve N status and making plants more tolerant of heavy metals. Scattered literature is harnessed to review the principles, advantages and disadvantages of the available technologies for remediating heavy metal contaminated soils and is presented.

Phytoremediation of cadmium-contaminated soil through multipurpose tree species

Phytoremediation of heavy metal-contaminated sites using trees may be preferred over crops due to capacity of trees to accumulate heavy metals in the wood which is biologically non-hazardous. An investigation was undertaken to assess the cadmium (Cd) phytoextraction potential of four multipurpose tree species viz. eucalyptus (Eucalyptus tereticornis Sm.), subabul [Leucaena leucocephala (Lam.) de Wit], dhrek (Melia azedarach L.) and shisham (Dalbergia sissoo Roxb.) at six rates of Cd applied in solution form through CdCl2·H2O (0, 10, 20, 40, 80 and 120 mg Cd kg−1 soil) and harvested after 18 months of growth in an alkaline loamy sand soil in earthen pots. Dry matter (DM) of leaves, stems and roots, Cd content of these constituents and that of soil before planting and after harvesting the tree species were determined. Subabul had the highest and eucalyptus the lowest total DM production at all levels of Cd. Total DM did not decrease significantly up to application of 40 mg Cd kg−1 soil (P > 0.05). The highest Cd level resulted in 49, 41, 26 and 43% reduction in total DM of eucalyptus, subabul, dhrek and shisham, respectively over control. Cadmium concentration was higher in leaves whereas uptake was higher in stems than the other components. Subabul had significantly highest uptake (0.05–71.4 mg pot−1) of Cd at various levels due its higher biomass whereas shisham had the lowest (0.05–28.2 mg pot−1) (P ≤ 0.05). Available Cd in the soil after harvesting of plants was the lowest in subabul and the highest in shisham pots. The upper critical level of available Cd in the soil at 20% reduction in DM was the highest for dhrek (85 mg kg−1) and the lowest for eucalyptus (46 mg kg−1). Therefore, dhrek was more tolerant to Cd but subabul had the greatest potential for phytoextraction of Cd from the soil.