JWSS - Journal of Water and Soil Science

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The main sources of cadmium in soil-plant continuum in amounts that might present a hazard are liquid and solid wastes of sewage sludge, farm manures and fertilizers. In the southwest of Iran (Khuzestan Province) over 50,000 ha of land is under sugarcane (Saccarum officinarum) cultivation and more than 80,000 ha will be under sugarcane by the end of the year 2000. In these sugarcane fields, about 400 kg ha^-1 diamonium phosphate (DAP) and 400 kg ha^-1 urea are applied annually. There is no data available to show the fertilizers impact on soil, water and plant contaminations in Iran with respect to cadmium. The objective of this research was to compare the extractable cadmium of virgin soils with that of soils under sugarcane.

 Four sugarcane growing stations viz. Haft-tapeh, Karoon, Shoeibieh and Ghazali with cultivation histories of 36, 20, 2 and 1 year, respectively, were selected. In each site, along a transect soil samples from 0-30 cm of both furrows and ridges of cultivated soils and of virgin soils were collected. Electrical conductivity (EC), pH, clay and organic carbon contents, CI and Cd of 101 soil samples were measured according to standard methods. Results showed that increasing either EC or CI increased Cd concentration with its maximum in virgin soils and its minimum in furrows.

 Results also indicated a slight decrease in the Cd content of cultivated soils.

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A factorial experiment with two levels of Zn (0 and 1.5 mg Zn kg^-1), five salinity levels of irrigation water (0, 60, 120 and 180 mM NaC1, and 120 mM NaNO₃) in three replications was conducted. Wheat (Triticum aestivum cv. Roshan) was seeded in pots. After plant harvesting, zinc and cadmium concentrations were determined in the shoot. Activities of metal species in the soil solution were predicted using the computer program MINTEQA2. Treating the soil with NaC1-salinized water increased total concentration of cadmium (Cd_T) as well as Cd²⁺, CdC1⁰₂, and CdCl⁺ species whereas, NaNO₃ treatment had no significant effect on Cd_T. Shoot Cd concentrations were positively related to Cd_T and soil solution Cl^- but negatively related to Zn_T. Application of Zn-fertilizer decreased Cd and increased Zn concentrations in shoot, significantly. The results of this experiment showed that Cl^- has an effective role in increasing mobility of soil Cd and its uptake by plant.

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Soil pollution and accumulation of heavy metals in crops in industrial areas are the most important bioenvironmental problems that threaten the life of plants, animals and humans. The objective of this study was to determine Ni, Mn and Cd distribution in soil and crops shoots around the Mobarakeh Steel Plant. In this study, we separated 50 zones based on soil utility maps taking into consideration the dominant wind direction (south-western to north- eastern). In each zone, soil was sampled at 0-5, 5-10, 10-20 and 20-40 cm depths (200 samples) and DTPA-extractable concentrations of Ni, Mn and Cd were determined in soil samples. Also 36 plant samples from shoots of 18 main crops were collected in the region and the concentrations of heavy metals were determined in crop samples. Results showed that maximum DTPA-extractable concentrations of Ni and Mn were in the northeast of the region in the 0-5 cm layer (4.2 and 312 mg/kg.soil, respectively) and decreased in 5-10,10-20 and 20-40 cm layers (2.7,2.7,2.1 and 200,212,146 mg/kg.soil, respectively). The concentrations of Ni and Cd in shoots of crops were undetectable with atomic absorption method. The concentration of Mn in rice shoots was 716.6 mg/kg.dry.m. It was higher than USEPA standards (15-100 mg/kg.dry.m). .

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Heavy metals have deleterious the effects on nodulation and N₂ fixation of Rhizobium- Legume symbiosis, due to their inhibitory effects on the growth and activity of both symbionts. This research has been undertaken to evaluate the effect of Cd tolerance of native rhizobial strains on diminution of the Cd detrimental effects on Sinorhizobium meliloti-alfalfa symbiosis. For this purpose, a greenhouse experiment was conducted based on Randomized Complete Block Design. The treatments in this experiment included: plants inoculation with 6 bacterial strains (sensitive, partially tolerant and tolerant to Cd), 5 levels of Cadmium (0, 2, 5, 10, 20 mg/kg soil) and non-inoculated control. In different levels of Cd, the effects of bacterial inoculation on root nodule number and total amount of nitrogen in plant shoot were compared. The results indicated that soil pollution by Cd even at 2 mg/kg had significant effect on symbiotic properties of rhizobial strains, and according to Cd tolerance of various strains, the mentioned effect was different. Decreasing effect of Cd concentration on root nodules and nitrogen concentration in plants that were inoculated with sensitive strains in comparison with plants inoculated with tolerant strains was 68.31% and 40.8%, respectively. In this research, R_95m was introduced as the best strain because of its ability for nodulation and nitrogen fixation.

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Heavy metals including cadmium (Cd) and lead (Pb) are entering agricultural soils from different routes and mainly due to human activities. Accumulated Cd and Pb in the soil would eventually enter the human and animal food chains and pose threat to their health. Therefore, evaluating heavy metal accumulation is necessary to prevent soil and environmental pollutions and should be considered by researchers as well as policy makers. This study was conducted to model the accumulation rates of Cd and Pb in the agro-ecosystems of Isfahan, Mobarakeh, Lenjan, Borkhar, Najafabad, Khomeinishahr and Felavarjan. Cadmium and lead accumulation rates in the agro-ecosystems were computed using a stochastic mass balance model which uses Latin Hypercube sampling in combination with Monte-Carlo simulation procedure. Agricultural information including crop types, crop area and yield, the type and the number of livestock, application rate of mineral fertilizers, compost and sewage sludge and also metal concentration in plant and amendments were used to quantify Cd and Pb accumulation rates. Modeling Cd and Pb accumulation rates indicated that the metals are accumulating in the agricultural lands in the studied townships. The largest Cd (18 g ha^-1 yr^-1) and Pb (260 g ha^-1 yr^-1) accumulation rates were found in the township of Isfahan but the minimum accumulation rates were found in township of Lenjan for Cd (3 g ha^-1 yr^-1) and Mobarakeh for Pb (10 g ha^-1 yr^-1). The major input route to agricultural soils is phosphate fertilizers for Cd but for Pb is manure on the regional scale. High application rates of sewage sludge and compost in agricultural lands in the township of Isfahan could result in considerable amounts of Cd and Pb entering the soils of this region.

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Sewage sludge application on farmland as fertilizer is commonly practiced in many countries. Sewage sludge is rich in macro- and micro- nutrients. However, high concentration of heavy metals in sludge may cause pollution of soil, groundwater and human food chain because of uptake of toxic metals by crops. The objective of this study was to determine residual and cumulative effects of sewage sludge on concentration of Pb and Cd in soil and wheat. Different levels of 0, 25, 50 and 100 Mg ha^-1 of sewage sludge were applied to the soil for four years. To study the cumulative and residual effects of the sewage sludge, applications were repeated on three fourth of each plot in the second year, on one half of plots in the third year and in one fourth of plots in the fourth year. Wheat grown in the plots, after the fourth year, soil samples from the 0-20 cm depth of the different parts of the plots were taken and analyzed. Wheat was also harvested roots, stems and grains were separately analyzed for the heavy metal concentritons. Cumulative sewage sludge application increased OM, CEC, ECe, total and DTPA-extractable concentration of Pb and Cd in soil significantly (P≤ 0.05). Residual sewage sludge in the soil also increased CEC, total and DTPA-extractable concentration of Pb and Cd significantly. Single sludge applications at different rates increased the DTPA-extractable concentrations of heavy metals. In subsequent years with no further sludge application, DTPA–extractable metal concentrations in soil decreased continuously approaching the levels in the control. However, even after four years, DTPA-extractable concentration of Pb and Cd, were still significantly higher in plots which received more than 50 Mg ha^-1 sludge than control. DTPA-extractable concentrations of Pb was closely correlated with total concentrations. Sewage sludge increased concentration of Cd in roots and stems and Pb in grains significantly. Cumulative effects on concentrations of Pb in grains, and Cd in stems were more than residual effects. The results of this study show that cumulative and residual effects of sewage sludge application increased concentrations of heavy metals in soil and wheat.

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Cadmium (Cd) and its rate in soil have received lots of attention because it is easily taken up by plant root, making it 20 times more toxic in comparison with other heavy metals. Knowledge about the factors affecting Cd availability and conversion of its chemical forms is, therefore, important. Sequential extraction has been used as a suitable method for identification of chemical forms and their relationship with plant availability, but in soils of Iran less attention has been paid to studying the change in chemical forms as affected by time. The present research was designed to study the change in Cd chemical forms as affected by application rate and time of incubation in two soil textural classes. A clay loam calcareous soil [Fine, mixed (calcareous), mesic Typic Calcixerepts] was converted to sandy loam soil by adding pure quartz sand and both soils were treated with 0, 5, 15, 30, and 60 mg Cd / kg soil as cadmium sulfate and incubated at room temperature near field capacity moisture. After 0, 1, 2, 4, 8, and 16 weeks, chemical forms of Cd were determined by sequential extraction. Results showed that, depending on the textural classes, about 82 and 87 % of applied Cd was converted to soluble+exchangeable, carbonate, and organic forms. In both soils carbonate fraction was dominant. Conversion of applied Cd to soluble+exchangeable and carbonate forms in sandy loam was higher than in clay loam. For organic, manganese oxide, amorphous iron oxide, and residual forms, the reverse was true. The crystalline iron oxide form was less than detection limit of atomic absorption in both textural classes. Increasing the application rate caused an increase in all forms of Cd but the percentage increase depended on the capacity of different soil components for Cd retention. Carbonate showed the highest capacity for retention. The effect of incubation time on conversion of Cd to different forms was significant. However, in almost all treatments more than 80 % of added Cd was converted to carbonate and organic forms immediately, and the proportion approximately stayed the same throughout the course of experiment.

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  Phytoremediation is a new technology that employs plants to remediate contaminated soils. This method compared to those that involve the use of large scale energy consuming equipments is an inexpensive method. Phytoremediation models are useful tools to further understanding the governing processes and also to manage the contaminated soils. A thorough literature review indicates that very few models have been developed for phytoremediation due to the complexity of the phenomena. The objective of this study was to develop a simple model for phytoremediation of lead and cadmium. A new formulation of phytoremediation was established based on soil and plant responses to heavy metal pollution. A large quantity of a sandy loam soil was thoroughly mixed to ensure homogeneous different concentration levels by lead and cadmium. These contaminated soils were transferred to some plastic pots. Land Cress (Barbarea verna) and Spinach (Spinacia oleracea L.) seeds were germinated in pots containing 8 kg of contaminated soil. Plants were harvested at five time intervals. The concentrations of Pb and Cd in the plant and soil samples were digested by wet oxidation and 4 M Nitric acid digestion methods, respectively, and were determined by flame and graphite furnace atomic absorption spectrometry methods. Proposed models then were calibrated using the collected data and validated quantitatively. The results indicated that the soil adsorption isotherms followed a linear form for both Pb and Cd concentrations. The results also indicated that the phytoremediation rate of Pb by Land Cress and Spinach are first-order function of Pb concentration in soil. In contrast, a zero-order function of soil Cd contaminations was obtained. Combining these two results of soil and plant responses to Pb and Cd pollution, a simple model with reasonable performance was derived to predict the time needed for remediation of soil Pb (R² > 0.98). However, in the case of Cd, the derived models appeared to be useful to make only some overall estimations of the remediation (R²≈^�0.70).

 

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Phytoremediation is a new, in-situ and emerging remediation technology for contaminated soils. This technology, compared to other methods, is a sustainable, natural, relatively cheap and applicable to large scale area. Modeling phytoremediation provides quantitative insight for the governing process as well as for managers to assess the remediated sites. The objective of this study was to introduce a macroscopic phytoremediation model for Ni and Cd- polluted soils. The proposed model assumes that relative transpiration reduction function can resemble total soilNi and Cd concentrations. Combining the related functions of soil and plant responses to soil Ni and Cd concentrations, the phytoremediation rate of Ni and Cd was predicted. In order to test the proposed model, large quantities of soil were thoroughly polluted with Ni and Cd. Upland Cress (Lepidum sativum) and Ornamental Kale (Brassica olerace var. Viridis) seeds were then germinated in the contaminated soils. The experimental pots were irrigated with fresh water to reach field capacity. Upland Cress and Ornamental Kale were harvested three and four times, respectively. At each harvest, relative transpiration, Ni and Cd contents of soil samples and plants were measured. Comparison of the maximum error, root mean square error, coefficient of determination, modeling efficiency and coefficient of residual mass indicated that the non-threshold non-linear model provide high efficiency to predict relative transpiration for Upland Cress and Ornamental Kale, respectively. The results also indicated that the proposed macroscopic model can well predict the phytoemediation rate of the Ni and Cd by Upland Cress (R2>0.83) and Ni by Ornamental Kale (R2=0.78).

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In this study, the effects of enhancing synthetic chelators (HEDTA, EGTA) and low molecular weight organic acids (LMWOA) such as citric acid were compared on cadmium (Cd) solution in soils that were artificially contaminated. Also Cd phytoextraction capability by radish (Raphanus Sativus L.) was studied. The experiment was laid out in a randomized complete factorial design where each treatment was replicated three times. Concentration treatments of cadmium using CdCl2 were 0(control), 5, 20, 60 and 100 mg Cd kg-1. After complete growth of plants, 6, 20 and 20 mMkg-1 soil HEDTA, EGTA and Citric Acid were added per pot, keeping a control without any chelator application. In order to determine cadmium concentration ten days after adding chelates, samples were taken from the plants and soil of pots. The results showed that in all treatments the concentration of soluble Cd in soil was higher than the control. Also the results showed that synthetic chelators as compared with LMWOA (Citric Acid) have increased the solution remarkably. Among the other chelates, HEDTA had significant effects on Cd solution. In the current study, Cd concentration in shoot and root of (Raphanus Sativus L.) was increased with enhancement of Cd concentration in soil. Cd concentrations in shoots of radish were higher than those in roots. This could refer to higher bioavailability and solubility of Cd. In the current study, in all the treatments with HEDTA Cd concentrations in shoot and root of (Raphanus Sativus L.) were increased as compared with other chelates..

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Arbuscular mycorrhizae (AM) and Plant Growth Promoting Rhizobacteria (PGPR) associations are integral and functioning parts of plant roots. These associations have a basic role in root uptake efficiency as well as improvement of plant growth in degraded environments including heavy metals contaminated soils. This study was conducted to evaluate the effects of heavy metal-resistant soil microbe's inoculation on bio-availability of Pb and Cd in soil, plant growth as well as metal uptake by Millet (Pennisetum glaucum), Couch grass (Triticum repens) and wild alfalfa (Medicago sativa). A soil sample was treated by different levels of Pb and Cd (soil 1). Native microbial inoculums were obtained from alfalfa rhizosphere soils adjacent to Pb and Cd mines in Zanjan region (soil 2), then added with weight ratio of 1:5 (w/w) to soil 1. Host plants including millet, couch grass, and alfalfa were grown in pots and kept in greenhouse conditions. At the end of growing period, shoot dry matter and Pb and Cd concentrations in plant and soil were measured. Results indicated that plants yield and Pb uptake were significantly higher in non-inoculated treatments (p ≤ 0.05). However, Cd uptake by plants was greater in inoculated treatments (p ≤ 0.05). Couch grass showed the most accumulation potential of Cd and Pb among the studied plants.

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Contamination of agricultural soils by heavy metals is a serious threat from both agricultural and environmental standpoints. Among heavy metals, cadmium (Cd) toxicity for humans and plants is of great concern due to its high mobility and phytoavailability in soil even at low concentrations. Opposite to Cd, Phosphorus (P) is an essential nutrient for plant growth. A greenhouse experiment was carried out in a completely randomized design to examine the influence of Cd, P and their interaction on the growth and chemical composition of spinach grown on a calcareous soil. Treatments consisted of four Cd levels (5, 10, 20 and 40 mg/kg soil as cadmium sulfate) and four P levels (0, 20, 40 and 80 mg/kg soil as mono-calcium phosphate) in three replicates. The results indicated that 40 mg Cd significantly decreased spinach dry weight by 47% but P application decreased detrimental effect of Cd on spinach dry weight. Also, phosphorus application significantly decreased Cd concentration in spinach aerial parts by 78%. Increasing Cd levels increased concentration of this element in spinach shoots. Addition of 40 mg Cd decreased P concentration by 21.5% in aerial parts. Zinc (Zn), manganese (Mn), calcium (Ca), and nitrogen (N) concentration significantly decreased with P application but increased concentration of sodium (Na). Cadmium application decreased Zn concentration but increased Ca, Na and N concentrations in spinach. Our tentative conclusion is that P application in P-deficient soils is probably effective in decreasing Cd concentration and the detrimental effect of Cd on spinach growth, indicating a negative interaction between these elements. Prior to any fertilizer recommendation, the results of this experiment should be verified under field conditions

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This study was carried out to investigate zinc (Zn) and cadmium (Cd) concentration in paddy soil and rice grain produced in central and southwest Iran in relation to soil and plant factors, and their intake in peoples diet was also assessed. Rice crops and associated surface soils (0-30 cm) were collected from 136 fields in Isfahan, Fars and Khuzestan provinces. The result, showed the DTPA-Zn concentration in more than 50% of paddy soils was less than its critical deficiency concentration (2 mg kg-1). The grain Zn concentration in more than 54% of the rice samples was less than 20 mg kg-1. The measured Cd concentrations in paddy soils and edible part of rice exceeded the world health organization (WHO) value in more than 12% of the samples. By considering the average daily rice consumption of 110 g per capita, the Zn intake from rice consumption was estimated about 10% needed for female and male adult. Diet intake analysis did not indicate any excessive dietary intake of Cd when Cd mean of concentrations in rice grain was 0.04 mg/kg, but based on the results of risk analysis, it is more than safely level for contaminated rice.

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Soil contamination with heavy metals, including Cd and Pb, is of serious concern. The aim of this study was to investigate the efficiency of Atriplex verucifera, Salicornia europaea and Chenopodium album for simultaneous remediation of soil exchangeable sodium percentage and Cd and Pb contamination in two soils with different properties. Two soils, including a saline-sodic-calcareous (S1) and calcareous (S2) soil, were selected. Different concentrations of Pb and Cd were then added to the soils. The contaminated soils were incubated under a wetting-drying cycle for nearly seven months. The plants, seeds were grown in pots containing different treatments of polluted soils and in control treatment (no Cd and Pb contaminations). The plant yields and concentrations of Pb, Cd and Na in the soil and plant samples were measured. A considerable accumulation of soil Cd by Salicornia and Pb accumulation by Atriplex and Salicornia was observed under unsuitable conditions of the saline-sodic soil, whereas Atriplex and Chenopodium had high capability for Cd in the soil S2. Also these plants caused the reduction of ESP in soil S1. The results revealed that these plants could be used for remediation of Pb and Cd contaminated soils. In this study, Salicornia with lower rate of yield reduction had the highest tolerance to Cd-stress. Understanding the complex plant and soil (salinity-sodicity and soil metal concentration) factors controlling the metals concentrations in the plants will help to design phytoextraction technology for arid, salt-affected regions.

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Nowadays, due to drought and water shortage, use of unconventional waters, particularly sewage, has become usual in agriculture whereas they often contain heavy metals. The present study was employed to evaluate the effect of urban wastewater of Shahrekord on growth, yield and accumulation of heavy metals (lead and cadmium) in balm (Melissa officinalis) as a medicinal plant with five treatments (0, 25, 50, 75 and 100 percent wastewater) and three replications in a completely randomized experimental design. The results showed that the highest shoot length, stem diameter and stem number, number of leaves and tillers are achieved in the treatment of 100 percent. The wet and dry weight of shoots and roots was highest in 100 % of wastewater. Oil percentage of the leaves was also the highest amount (1.23 %) in 100 % of wastewater. Accumulation of lead in roots and aerial parts and its transmission factor was not significant for the treatments. However, the highest concentration of lead in root (0.057 mg/kg) and shoots (0.013 mg/kg) was observed in 100 % of wastewater and the lowest one was related to zero percent of wastewater treatment. The lead concentration was less than the critical limit for all the treatments. The amount of cadmium was undetectable in all the plant samples. The results of this study demonstrated that urban wastewater of Shahrekord, in addition to providing water, increases plant growth and essential oil.

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Cadmium is a toxic element in plant nutrition and is considered as a contaminant of food and feed. A greenhouse experiment was carried out to examine the effects of combined application of cadmium and zinc on responses of wheat on a clay loam soil texture. This experiment was designed in a factorial experiment with randomized complete block design (RCBD) and four replicates per treatment. Three levels of cadmium (Cd 0, Cd 50 and Cd 100 mg kg-1) and three levels of zinc (Zn 0, Zn 50 and Zn 100 mg kg-1) were added to the pot in factorial(9 treatments), and then Chamran seed variety of wheat (triticum aestivum L.) was planted in each pot. The statistical analyses showed that Cd application significantly (P0.01) decreased grain, straw, and total yield, but Zn application increased these parameters significantly (P0.01). Application of Cd separately decreased the grain yield by 61.5 while application of Zn separately increased the grain yield by 36.9. Cd application increased the Cd concentration and uptake by grain and straw as well as total uptake but by increasing Zn application, Cd uptake was decreased by wheat. Cd concentration was higher in straw than that grain, but Zn showed a different trend. Decreasing Zn applications decreased total uptake of Cd from 42.9 in Zn0 to 7.8 mg kg-1 in Zn100 treatment. Although this soil was very calcareous, this characteristic did not control Cd absorbtion.

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Mycorrhizal fungus colonization of roots may modify plant metal acquisition. In order to study the role of external hyphae of mycorrhizal fungi in metals transferring, the root and hyphal growth zone were separated by 30 µm nylon meshes. Plants were inoculated with G. mosseae and G. intraradices and grown in the root compartment. Six combinations of metals (400 mg of Zn, 25 mg of Cd, 400 mg of Zn + 25 mg of Cd, 50 mg P, 50 mg of P+ 400 mg of Zn + 25 mg of Cd, and no metal kg-1 soil sample) were added to the hyphal compartments. This experiment was carried out as a completely randomized design (CRD) with factorial arrangement in three replications. The results showed that dry shoot weight and phosphorus concentration in mycorrhizal treatments increased significantly compared with non mycorrhizal treatments. of the two fungal species, G. mosseae had more effect on phosphorus concentration in white clover plant. AM fungi increased the Zn concentration in shoot and root of white clover. AM fungi also significantly increased cadmium concentration in root of mycorrhizal treatments compared to non mycorrhizal plants. of the two fungal species, G. intraradices accumulated more cadmium in clover roots. ALL in all the results demonstrated that AM fungi increased phosphorus and Zn transferring to the shoots while cadmium transferring was decreased by stabilizing in the roots.

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Heavy metals in water resources are one of the most important environmental problems in most of countries. Up to now, various methods for removing these metals including using low price materials have been used. In this study, two new absorbents (zizyphus spinachristi leaf and its fly ash) were studied for adsorption of cadmium from aqueous solutions using batch experiments. The effect of contact time, pH, and amount of adsorbent on adsorption efficiency was evaluated and the best kinetic and isotherm model was determined. Results showed that optimal absorption of pH was 5 and 6 for zizyphus spinachristi leaf and its fly ash, respectively. The equilibrium time was 45 min for zizyphus spinachristi leaf and 30 min for ash. Adsorption efficiency was increased by increasing the adsorbent dose. By comparing the parameters of isotherm models, it was observed that the cadmium adsorption capacity of fly ash (4.27 mg/gr) was higher than that of zizyphus spinachristi (3.91 mg/gr).

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The purpose of this study was to investigate cadmium adsorption through Freundlich and Langmuir equations in sediments of Karun River in three hydrometric stations (5th Ahvaz Bridge, Darkhovin and Khorramshahr) in the low-water and high-water seasons. Fitting of data from experiments on cadmium absorption to Freundlich and Langmuir equation showed they are compatible. According to the conducted experiments, there was a significant difference at 0.01 levels between b coefficient of Langmuir equation with the organic matter percentage and the clay content in both Low and high water seasons, while there was no significant difference between k coefficient of Langmuir equation with the organic matter percentage and the clay content for the two seasons. The results also suggested that there is a significant relationship between Kf of Freundlich equation with the organic matter percentage and clay content, at significant levels of 0.05 and 0.01 for the organic matter percentage and the clay content, respectively. Comparison of the means of low and high water seasons revealed that there is no significant relationship between Langmuir coefficients, whereas in Freundlich equation, a significant difference at 0.01 level was observed between kf coefficients. Generally, the obtained results indicated that cadmium adsorption by sediments in low-water season is higher than high-water season. Also, cadmium adsorption by the 5th Ahvaz Bridge sediments due to the sandy texture was less than those adsorbed by both Darkhovin and Khorramshahr sediments.

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Stabilizing heavy metals in polluted soils is a method to prevent them from entering plants. Clay minerals are considered good sorbents for heavy metals due to their low cost, high abundance, easy manipulation and harmlessness to the environment. The objective of this study was to investigate the potential of clay deposits containing smectites and palygorskite to sorb cadmium and to reduce its movement into canola. Two selected deposits are located in the Isfahan Province. Physical and chemical characteristics of clay deposits were determined. The clay fraction was then separated from each deposit sample. This study showed that palygorskite was the dominant clay mineral in deposit sample 1 and smectites in deposit sample 2. These clays were then used as an amendment to plant growth medium. Pot experiment was carried out with canola (Brassica napus) as a test plant with 3 replicates. Treatments included three growth media: smectite + quartz sand, palygorskite + quartz sand and pure quartz sand (control treatment) under 3 Cd concentrations: 0, 2.5 and 7.5 ppm. Results obtained from the pot experiment indicated that deposits containing smectite and palygorskite were very useful in stabilizing cadmium in polluted soils and could prevent Cd from entering plant. Smectite clay mineral could retain a higher quantity of cadmium as compared to palygorskite. Plants in pots amended with smectite had a higher growth rate as compared to those in control and palygorskite amended pots. Cadmium accumulation in plant roots was much higher than that in shoot. Furthermore, the higher Cd concentration in growth media resulted in the higher amount of Cd uptake by the plant.