This study has investigated cadmium immobilization in the soil at the present of nano and micro titanium dioxid and the role of humic acid in nanoparticle stability and cadmium adsorption on nano and micro particles. The results of this study showed that in the soil contaminated with cadmium in suspension conditions, humic acid increased soluble cadmium in supernatant suspention and therfore increased cadmium availability in the soil. Modification of TiO2 nanoparticles surfaces with humic acid increases adsorption of cadmium at the nanoparticle surfaces. Also, since microparticles have reduced the soluble cadmium in supernatant suspensions and the concentration of exchangeable cadmium to a greater extend than nanoparticles, it can be concluded that the effect of microparticles in reducing available cadmium in the soil is greater than that of nanoparticles.

Application of organic amendments as a cheap material is increasing to modify soil physical, chemical and biological properties of arid and semi-arid regions. Applying municipal waste compost can probably increase soil pH, organic carbon percent and cation exchange capacity and thereby decreaseing heavy metal availability such as cadmium. On the other hand, applying soil natural clay such as zeolites can probably increase cation exchange capacity that decreases the heavy metal availability in soil and plant. However, this may be affect soil nutrition availability. This research was done to investigate the effect of applying Arak municipal waste compost and zeolite on decreasing cadmium availability in a loamy soil.
A loamy, non-saline soil with low organic carbon percent was sampled from soil surface layer (0–15 cm) in the research field of Arak Azad University. A factorial experiment with a randomized complete block design with 3 replications was conducted in greenhouse conditions.. Treatments were consisting of applying Arak municipal waste compost at the rates of 0, 15 and 30 Mg ha-1. The soil was polluted with cadmium from cadmium chloride source at the rates of 0,5,10, 15 and 20 mg Cd kg-1 soil and incubated for one month. On the other hand, zeolite clay (clinoptilolite) was added to the soil at the rates of 0 and 10 % (W/W). Then, corn (Zea mays L. single grass 704) seeds were sown. After 60 days from the experiment, soil physio-chemical properties and soil and plant Cd concentration were measured.
The results showed that increasing application of municipal waste compost from 0 to 30 Mg ha-1 significantly increased CEC (3 units) and pH in the soil under growth of corn. Increasing the amount of Arak municipal waste compost from 0 to 15 and 30 Mg ha-1 in a 20 mg Cd kg-1 soil without applying zeolite, caused a significant decrease in DTPA-extractable Cd by 19 and 30 %, respectively. Similar to this result, root and shoot Cd concentration were decreased, as, applying 30 Mg ha-1 Arak municipal waste compost (in a soil polluted with 20 mg cd kg-1 soil) without receiving zeolite caused a significant decrease in root and shoot Cd concentration by 37 and 66%, respectively. In addition, applying 10 % (W/W) zeolite clay in a cadmium polluted soil (20 mg Cd kg -1soil) without municipal waste compost decreased the DTPA-extractable Cd by 7%. Root and shoot Cd concentration was also decreased by 16 and 23%, respectively.
The lowest DTPA-extractable Cd was in a 5 mg cadmium polluted soil treated with 30 Mg ha-1 municipal waste compost and 10% (W/W), white the greatest amount of DTPA-extractable Cd was observed in a polluted soil with 20 mg cd kg-1 soil without receiving municipal waste compost and zeolite. The result of this experiment showed that applying zeolite and Arak municipal waste compost can increase the cation exchange capacity and thereby decreasing cadmium concentration in soil or plant. However, the other effect of applying organic amendments cannot be ignored.

Any cadmium (Cd) contaminated soil might cause reduction in plants’ yield and increase the hazard of Cd-contaminated plants consumption by both human and animals. The research aimed to investigate the effect of EDTA chelate on Cd uptake in pot marigold (Calendula officinalis L.). A factorial experiment using randomized complete blocks was used in three replications. Treatments included application of 0(C0), 25(C25), and 50(C50) Mg ha-1 cow manure in a Cd polluted soil [ 0(Cd0), 5(Cd5), and 10 (Cd10) mg Cd kg -1 soil] and two rates of EDTA chelate (0 and 2.5 mmol kg-1 soil). Applying 2.5 mmol EDTA chelate caused significant increase in shoot Cd uptake by 21% and 25% in a Cd polluted soil (10 mg Cd kg -1 soil) treated with 25 and 50 Mg ha-1 cow manure, respectively. Also, addition of 2.5 mmol EDTA chelate caused an increase in the root and shoot bio-concentration factor. The results of this experiment showed that applying 2.5 mmol EDTA would increase the Cd availability, which could be considered as a factor that plays an important role in Cd remediation in soils treated with organic amendments.

Soil, as an important component of terrestrial ecosystems, plant growth media, and a habitat of diverse living organisms commonly encounters a variety of abiotic stresses. Soil microorganisms play an important role in maintaining soil quality and functioning, since they are responsible for the decomposition of dead organic material, nutrient cycling and degradation of hazardous organic pollutants. Metal toxicity and salinity are the major abiotic stresses affecting soil microbial activity and community structure in many areas of the world, in particular arid regions. Salinity may prompt the negative influences of soil pollution on soil microbial activity. On the other hands, application of organic amendments to saline soils or toxic metal-polluted soils may alleviate the negative consequences of these two abiotic stresses on soil microbial activity and population.

This study was conducted under controlled laboratory conditions at Shahrekord University. The main aim of this study was to investigate the effects of salinity and plant residue as an organic amendment on concentrations of soluble elements, enzyme activity and substrate-induced respirations (SIR) in a calcareous soil polluted with cadmium (Cd) over a three-month incubation experiment. A factorial experiment with two levels of cadmium (0 and 30 mg kg-1), three levels of salinity (1.35, 7.5 and 15 dS m-1) and plant residue treatments (with and without alfalfa residue) was conducted using a completely randomized design with four replications. Using cadmium chloride salt, the soil was contaminated, and subsequently amended with alfalfa residue (1%, w/w). After thorough mixing of soil and plant residue, salinity treatments were applied using NaCl salt. To reactivate the microbial population and for the aging effect, soil moisture was set at 70% of field capacity, and containers were pre-incubated at room temperature for 4 weeks. The samples were then incubated at 25±1 oC for 98 days.

Increasing salinity levels resulted in an increase in soluble Na concentration, a reduction in soil enzyme activity and SIR, and a decline in the concentrations of soluble Ca, Mg and K. The harmful impact of soil salinity on microbial properties was much greater in Cd-polluted soils than unpolluted soils.

Results indicated that addition of plant residue reduced the negative impacts of salinity and Cd pollution stresses on soil microbial and enzyme activity, and that resulted in increases in the concentrations of water soluble elements.The findings of the current study confirmed that application of adequate organic amendments can decrease Cd toxicity, enhance substrate availability and maintain soil microbial and enzyme activity in saline and polluted soils with substrate limitation.

In the past few decades, accumulation of heavy metals in soils has increased as a result of human activities. The objective of this study was to evaluate the effect of common reed nano-biochar and Fe-modified nano-biochar on cadmium (Cd) mobility and fractionation in a Cd-contaminated soil. This study was carried out in 1399-1400 as a factorial experiment based on a completely randomized design (CRD) with two factors including absorbent type (at four levels including biochar, modified biochar, nano-biochar and modified nano-biochar), and biochar application levels (0, 0.5 and 1% w/w) in three replications under laboratory conditions. After treatments’ application, the soil samples were incubated for 90 days. At the end of incubation period, Cd availability and fractionation were measured and Cd mobility factor was determined. The results indicated that with the application of all absorbents (especially at 1% w/w level), concentration of available Cd, exchangeable and Cd bound to carbonate fraction were significantly decreased, while Cd bound to Fe-Mn oxides, Cd bound to organic matter and residue fraction of Cd significantly (P<0.05) increased. The Cd availability in modified nano-biochar treatment (1%) decreased by 26.37 % compared to the control. Results also indicated that nano-biochar had a more significant impact than raw biochar on the immobilization of Cd and decrease its mobility in the soil. In addition, modified-biochar and nano-biochar had more efficiency than raw biochars on the Cd stabilization in the soil. In general, the results revealed that common reed nano-biochar and modified nano-biochar with FeCl2 can be suitable absorbent for stabilization of Cd in contaminated soils.

Cadmium (Cd) contamination has been a widespread concern in paddy soils because of its subsequent transfer to the food chain. Biochar amendment is proposed to stabilize Cd in the contaminated soils. However, the pristine biochar shows limited functionality towards Cd sorption in practice. Recently, Mg-modified biochars have attracted much attention for their low toxicity. These biochars are coated by MgO or Mg(OH)2 precipitates during the pyrolysis process. Magnesium chloride (MgCl2)-modified biochars have been used widely in the removal of heavy metals from the aqueous solutions. However, there is little literature about their performance in soils. The present study therefore was conducted to investigate the effects of application of unmodified and MgCl2-modified rice husk biochars on the kinetics and isotherms of Cd sorption in a calyey paddy soil.

The unmodified and MgCl2-modified biochars were produced from rice husk at 600°C. Some relevant characteristics of the produced biochars (including elemental composition, pzc, pH1:10, ash content and BET surface area) were determined. Moreover, the studied soil was taken from a paddy field (0-20 cm) in the Qaemshahr region of Mazandaran province. The biochars (< 0.5 mm) were added to the soil samples at three levels (0, 3, and 5% w/w) and the amended soils were incubated at 25°C for 45 days. Then, the kinetic experiments of Cd sorption at a concentration of 375 mg Cd/L at times of 0.25, 0.5, 1, 2, 4, 8, 16, 24 and 48 hours and the isothermal experiments of Cd sorption at concentrations of 50, 100, 150, 200, 300, 350, 400, 600 and 800 mg Cd/L were performed. In both kinetic and isotherm experiments, a 0.01 M KCl solution was used as the background electrolyte. Finally, the relevant kinetic and isotherm models were fitted to the sorption data and their parameters were calculated.

Biochar characterization indicated that modification with MgCl2 resulted in an increase of the O/C ratio (from 0.27 to 0.48) and pH (from 7.67 to 8.60). This modification also increased the H/C ratio (from 0.032 to 0.071) and the specific surface area (from 195.6 to 231.2 m2/g). As a result, the MgCl2-modified biochar was more hydrophilic and less carbonized than the unmodified one. Moreover, the characteristic peaks of the MgCl2-modified biochar (3700, 1428 and 500 cm-1) were present in its FTIR spectrum. The results revealed that about 74 to 89% of the Cd sorption by the soils occurred in times less than 2 hours. With MgCl2-modification, the sorption equilibration time was reduced from 48 hours to 24 hours. In contrast, the unmodified biochar had no considerable effect on the Cd sorption kinetics. Among the kinetic models, the Elovich model with lower SEE was the best to fit the Cd sorption kinetic data. The intra-particle diffusion model was not satisfactory for Cd sorption on the biochars. Freundlich model with lower SEE well described the Cd sorption isotherms. Application of 3% and 5% MgCl2-modified biochar increased the Freundlich KF parameter by 2.4 and 2.8 times as compared to the control. Moreover, the aforementioned treatments increased the heterogeneity parameter of the Freundlich model (n) from 3.48 to 6.08. The Temkin model could not reasonable fit the sorption data. In contrast, the unmodified biochar did not show any considerable effect on the Cd sorption capacity of the clayey soil used in this research. This finding means that the unmodified biochar could not improve the sorption performance of negatively charged soil clay particles.

According to the results obtained, it could be concluded that the Cd sorption behavior of the soil treated with unmodified rice husk biochar was similar to that of the untreated soil. Whereas, the MgCl2-modification improved both sorption rate and sorption capacity of the soil for Cd. Application of MgCl2-modified biochar improved the Cd sorption properties of a clayey soil with high intrinsic sorption ability. Thus, this may be a promising approach in remediation of Cd-contaminated paddy soils with the aim of reducing Cd mobility and availability. However, there is need to do more research to create awareness about the importance of biomass nature as well as pyrolysis temperature, the ratio of MgCl2 to biomass, the mechanism of Cd stabilization and the desorption of Cd from soils treated with MgCl2-modified biochars.

Heavy metals uptake and their distribution in plants are different. In addition to the genetic factors, environmental factors such as interactions of heavy metals with essential elements are very important on the amount of heavy metals uptake. In this study, the effects of iron and manganese on accumulation of cadmium in shoot and root of sunflower and corn in different concentration of those elements in a hydroponic condition was investigated. The results showed that cadmium uptake in root and shoot of sunflower were higher significantly compared to corn. The concentration of cadmium decreased in the shoot of sunflower and corn with increasing the iron availability. Cadmium concentration of corn root was not affected by iron availability but cadmium concentration in sunflower root was reduced dramatically. Manganese availability had less effect on cadmium accumulation of root and shoot of both plants. Cadmium concentration of root and shoot of sunflower increased by manganese availability but it was different in corn plant.

Heavy metals enter to human food chain through the plant and soil contamination. It is very important to evaluate the affecting factors on plant uptake of heavy metals. In this study the effects of copper and zinc availability on cadmium uptake of root and shoot of corn and sunflower was investigated. The experiment was carried out with a factorial arrangement, two species of plants (sunflower and corn), two cadmium concentrations (0.02 and 0.05 mg /l) and three concentrations of zinc and copper (0, 0.025 and 0.05 mg/l for Zinc and 0, 0.01 and 0.02 mg/l for copper) based on a completely randomized design with three replications. The results showed that copper and zinc availability had no effect on cadmium uptake of corn plant. The highest concentration of cadmium in root corn was observed in 0.05 mg/l of cadmium concentration without copper application. In sunflower, the addition of 0.05 mg/l zinc to medium decreased cadmium uptake in 0.02 and 0.05 mg/l cadmium treatments. The synergistic effect of cadmium and zinc was observed in 0.05 mg/l cadmium and 0.025 mg/l zinc treatments. Zinc concentration had a positive effect on cadmium uptake in root and shoot of sunflower in this treatment.

Soil and water pollution, especially pollution by heavy metals such as cadmium,, has been noticed in many modern urban and industrial societies. If heavy metals accumulate in the soil, the capacity of the soil to keep the metals decreases, as a result, they enter the product and their bioavailability increases. Today, the use of biochar is suggested as a healthy method to control heavy metal pollution in the soil.In this research, in order to investigate the concentration of cadmium metals in soil and leaves in the exposure of cadmium stress and using biochar to investigate some physiological indicators of leaves and also to investigate the level of soil composition in 2 varieties of grapes in Malayer city, grape cuttings in plastic pots It was cultivated in the research greenhouse of Malayer University and Faculty of Agriculture.

In this experiment, the effect of biochar on two grape varieties (white Soltana and perlet) was investigated in the face of 100 mg/kg cadmium stress. After applying cadmium stress and using biochar (3% by weight) in the tested pots, The soils of the rhizosphere area were collected after 2 months of applying stress, and the cadmium concentration was done in the form of 5-stage classification in the research laboratory of Malayer University and finally analyzed by atomic absorption device. Leaf samples were also collected after about 2 months of applying stress and biochar, and physiological indicators such as ion leakage, chlorophyll, phosphorus and relative water content were measured.
The data related to each treatment (three replications) were carefully recorded and analyzed using SPSS software. EXCEL software was used to draw graphs. Duncan's test was used at a significance level of 1%.

The results showed that cadmium stress decreased the amount of chlorophyll and the relative content of water and also increased the amount of ion leakage. It was also observed that the application of biochar in both grape varieties increased the relative content of water, chlorophyll and phosphorus and reduced the amount of ion leakage to some extent. In the chemical forms of the soil, the use of biochar caused the reduction of exchange and carbonate forms and the increase of organic, oxide and residual forms. Biochar changed the easily replaceable parts of cadmium to those that are less available. In the conditions of cadmium stress, the use of biochar in soil can play a very important role in plant indicators such as relative water content, ion leakage, chlorophyll and phosphorus.The application of biochar decreased the fraction of exchangeable and carbonated cadmium, while the forms bound to Fe-Mn oxide, organic form and residual fractions increased.It was observed that the availability of heavy metals in the soil was significantly reduced with the addition of biochar compared to the control. Biochar significantly reduced ion leakage in both grape cultivars compared to untreated soil. In the organic form, the white Soltana variety in the presence of biochar and stress of 100 mg/kg of cadmium in the soil (6.57) compared to the samples without the presence of biochar (3.39) had an increase of 48.40% in the average concentration of cadmium. In Perlet cultivar, the percentage of increase was 21.45%, all of which showed an increase in organic form in the presence of biochar.Cadmium in soil in exchangeable and carbonate forms decreased after biochar application.In the residual form, the White Soltana variety in the presence of biochar and stress of 100 mg/kg of cadmium in the soil (20.88) compared to samples without the presence of biochar (15.47) had an increase of 34.97% in the average concentration of cadmium. In Perlet cultivar, the percentage of increase was 30.34%, which all showed the increase of residual form in the presence of biochar. Our results showed that the application of biochar can reduce the availability and toxicity of cadmium.

According to the results of this research, the application of biochar in the soil can be considered as an efficient management solution to control cadmium in areas contaminated with this heavy metal and can cause positive changes in plant leaf indices.Changes in the concentration of cadmium in different soil forms of grape cultivars as a result of the use of grape trunk biochar show that the use of biochar is a good strategy to reduce the risks of transferring cadmium to humans and the environment in metal-contaminated soils.

Background and Üsing of plants is increased to cleaning up of contaminated soils with heavy metals. The important challenge of phytoremediation, is heavy metals availability decreasing in soil by plants. This study was performed to determine of ËDTÂ, Çitrate ammonium and Phosphate ammonium effect on availability of Pb and Çd in soil by native plants of Mazandaran province. Sampling soils with concentration 0f 400 and 20 mg/Kg as Pb and Çd was mixed and translated in to poly ethylene pot. This study, 3 native plants of north Ïran (Âbutilon theophrasti, Âmaranthus retoflexus, Zea maize) was studied. Lead and Çadmium concentration in soils and plants was determined by Âtomic Âbsorption Spectrometry (ÂÂS) Perkin-Ëlmer 603 of analysis lab of Tehran university. Maximum of lead and Çadmium concentration was related to ËDTÂ treatment, so that concentration of Lead in Zea maize, Âmaranthus retroflexus and Âbutilon theophrasti was 686.5, 538 and 264.5 mg/Kg respectively. Minimum concentration of Lead and Çadmium was related to Phosphate ammonium treatment in studied plants. Mean concentration of Lead in shoots of plants more than roots and Çadmium concentration in roots of plants in all treatments more than shoots. This study, maximum of Lead and Çadmium concentration was in Zea maize and Âmaranthus retroflexus respectively.Çonclusion: Phytoremediation of contaminated soils with heavy metals in industrial places of north Ïran is important, because of low concentration of these elements and high concentration of Lead and Çadmium in native inedible plants.