مقالات رزومه محسن حمیدپور

Layered double hydroxides (LDH) have gained considerable attention for their potential application in agriculture, serving as a slow release sources of essential nutrients for plants. The appraising of LDH as a favorable fertilizer is in the early development, and more studies on the nutrient release mechanism of LDH are needed to answer the question of how LDH could replace commercial fertilizers for providing the stable nutrients for plants. Although several studies on the release of P from LDH exist in the literature, no information regarding ratios of divalent cation (M2+) to trivalent cation (M3+) in LDHs on phosphate release from LDHs is available. So, it is important to raise our knowledge about various parameters like pH and time on the solubility of LDHs. This study aimed to investigate the effects of pH and the ratios of M2+/M3+on the kinetics release of P from Mg-Al-LDH.

All the chemicals in this research, such as magnesium nitrate hexahydrate (Mg (NO3)2.6H2O) and aluminum nitrate nonahydrate Al(NO3)3.9H2O were of analytical grade and obtained from Merk (USA). The solutions were made with decarbonated pure water without impurities (electrical resistivity = 18 MΩcm). Two nitrate forms of Mg-Al-LDH were synthesized using the co-precipitation method at constant pH by varying the Mg/Al ratios (2:1 and 3:1) in the precursor solution. Briefly, 50 mL of 1M solution containing nitrate salt of divalent cations (Mg(NO3)2.6H2O) and trivalent cations (Al(NO3)3.9H2O) in the appropriate ratios (2:1 and 3:1) were added simultaneously for 2h to 400 mL of 0.01M solution of sodium hydroxide while being stirred vigorously in a nitrogen atmosphere. The pH was kept at 9.5 by adding volumes of 3 M NaOH. Afterward, the material was ripened in the synthesis mixture for 2 h and centrifuged at 3000 rpm for 20 min. The precipitates were washed by three washing-centrifugation cycles with Milli-Q water and subsequently dried at 70 °C. In this study, LDH-P was made by ion exchange. The LDH-N were treated with 0.05 M KH2PO4 solutions at pH 7.2. The suspensions were shaken end-over-end for 24h, followed by centrifugation, washing, and drying as described above. After digesting the dried LDHs in aqua regia (3:1 HCl/HNO3), the total P concentration of the LDHs was determined. The chemical composition of the synthesized LDHs was determined by graphite furnace atomic absorption spectrophotometry (SavantAA, GBC) after acid digestion (3:1 HCl/HNO3). Crystallization and morphology of the LDHs were characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The XRD patterns were prepared using an x-ray diffractometer (Panalytical x Pert Pro, Netherlands), at scan step time of 1s from 2θ=5° to 2θ=70° (40KV and 30 mA), and with a step size of 0.0260, which were used to identify the mineral phases. The phase purity was surveyed by comparing these XRD diagrams with those found in the literature. The SEM photographs were gained on a scanning electron microscope (SigmaVP, Germany). Fourier Transform Infrared (FTIR) spectrum was done on a Nicolet iS10 FT-IR spectrometer by utilizing KBr pressed disk technique.A batch study was done to determine the effect of different ratios of M2+/M3+ in LDHs at different pH 6.0 and 8.0 on the release of P from LDHs. Briefly, 0.01 g of synthesized LDH were put in a centrifuge tube mixed with 10 ml of 0.03M KNO3 at initial pH=6 and 8. Suspensions were shaken at a constant temperature (25±0.5 °C) and agitation (180 rpm) by using an incubator shaker for 8h. Phosphorus concentration in supernatant solutions was measured by vanadate yellow method at 470 nm wavelength.In order to investigate the kinetics of phosphorus release, LDH-P1 (2:1) and LDH-P2 (3:1) were used at two initial pHs of 6 and 8. First, 0.012 g of LDH sample was placed in 120 ml of KNO3 electrolyte solution (with ionic strength of 0.03 M) in an Erlenmeyer flask. The flasks were shaken for 5 to 1175 min by an incubator shaker at 100 rpm. Then the suspensions were centrifuged at a speed of 4000 rpm for 20 minutes and the phosphorus concentration was determined by the method described previously. All experiments were performed with three repetitions. Two equations (pseudo-second-order and parabolic diffusion) were used to fit the kinetics data.

According to the XRD patterns, the sharpness and reflection of diffraction planes (003) and (006) pertained to layer structures. The basal spacing as calculated by Bragg’s law (nλ = 2d sin θ) were 7.94 and 8.0 Å for Mg-Al-NO3 with M+2/M+3 2:1, 3:1 respectively. The XRD patterns of the LDHs exhibited a distinct characteristic reflection (003), which indicated that the basal spacing decreased as the Mg/Al ratio decreased (higher AEC). In addition, the decreased basal spacing is linked with a decrease in the interlayer spacing. The different basal spacing of LDH were related to the layer charge density, the content of water, and the reorientation of anions in the interlayer of LDH. The intercalation of phosphate anions into Mg/Al LDH is in adaptation with the change toward lower 2θ angles of the (001) reflections corresponding to the expansion of the basal distance d003 compared to the host Mg/Al-NO3-.Two bands of FT-IR spectrums around 3470 and 1655 cm-1 for all synthesized LDH materials designate stretching vibrations of the O-H group of hydroxide layers and the interlayer water molecules. The band vibration of phosphate was perceived at 1051 cm−1 and 1064 cm-1, reflecting the formation of inner-sphere surface complex (M-O-P) between dihydrogen phosphate ions and MgAl-LDH materials. It indicated that the phosphate exchange process may be resulted in the formation of bidentate and monodentate surface complexes. According to the SEM images, the well-crystallized and plate-like morphology were typical for layer double hydroxides. The results of the X-ray energy dispersive spectroscopy (EDS) analysis showed, the only elements that existed in the LDH-N were Mg, Al, N, and O, whereas Mg, Al, P, and O were detected in the LDH-P. The results showed that increasing the pH from 6 to 8 in the presence of 0.03 M potassium nitrate background electrolyte led to an increase in phosphorus released from both types of LDH. For example, by increasing the initial pH of suspensions from 6 to 8, the amount of cumulative phosphorus released from LDH-P1 increased from 38.59 mg kg-1 to 41.91 mg kg-1 at equilibrium. In all studied pHs, phosphorus release from LDH-P1 in background electrolyte was lower than LDH-P2. For example, at pH 6 and 8, the amount of cumulative phosphorus released from LDH-P2 was 1.46 and 1.33 times higher than LDH-P1 at equilibrium, respectively. The cumulative phosphorus release kinetics from the studied LDHs showed that the amount of phosphorus release accelerated with increasing time. Phosphorus release from LDH continued at a higher rate from 0 to 400 minutes in the first stage and at a slower rate during 400-1175 minutes. Also, based on the results, among the studied kinetic equations, pseudo-second-order and parabolic diffusion equations had the best fit on phosphorus release data.

The results of this research showed that the release of phosphorus from LDH is dependent on time, pH and the type of LDH. Based on the results of fitting the kinetics models to the experimental data, the release rate of phosphorus from LDH-P2 (3:1) was higher than that of LDH-P1 (2:1). Cumulative phosphorus release from LDH-P2 compared to LDH-P1 was 46.54, 33.61% higher at pH 6 and 8, respectively.

One of the most important factors limiting the growth and yield of plants is the zinc deficiency. Considering the importance of recycling rubber tires and the possibility of using them in agriculture, the present study aims to investigate the effect of organic ligands on the availability of Zn in rubber ash-treated soils. The present research was carried out in factorial form in a completely randomized design with three replications under greenhouse conditions. The treatments included four levels of rubber ash (0, 0.25, 0.5 and 1 %w/w) and three levels of organic ligands (control, citric acid and EDTA with a concentration of 1.5 mmol kg-1 soil). The results showed that the application of organic ligands in soils treated with rubber ash could not affect the vegetative traits of corn plants, while the concentration of Zn in the aerial organs and plant roots increased with the application of organic ligands in pots treated with rubber ash. The highest concentration of Zn was observed at the level of 1 %w/w rubber ash and with the use of EDTA ligand. In addition, the concentration of Zn extractable by DTPA in the soil increased significantly with the use of rubber ash treatment. The results also showed that the treatment of rubber ash, ligand and their interactive effects did not affect the concentration of Cd and Pb in plants. The results of this research showed that the tire rubber particles could provide zinc required by the plant in a short period of time. Of course, it is necessary to study the effects of gases produced during rubber ash production on human health and the environment.

In order to investigate the effect of calcium-enriched sepiolite under stress conditions on the concentration of nutrients in cucumber, an experiment was conducted with two factors of stress (control, salinity stress: 70 mM sodium chloride, alkalinity stress: 70 mM sodium bicarbonate, and combined salinity and alkalinity stresses: 70 mM sodium chloride + 70 mM sodium bicarbonate) and the levels of sepiolite (0, 10 and 20% w/w) in a completely randomized design. The results showed that calcium-enriched sepiolite had favorable effects on the concentration of nutrients and the dry weights of plant root and shoot. For example, in non-stressed conditions, with the application of 10 %w/w sepiolite, in addition to a 94% increase in the dry weight of the shoot, the concentrations of Mg and Ca in the shoot increased by 15 and 45%, respectively. With the application of 20% w/w sepiolite, the dry weight of the shoot increased by 80% in the conditions of salinity stress. Additionally, this treatment resulted in significant increases in the concentration of Cu in the shoot, Ca in the root, Mg in the root and shoot, and Fe in the root, with increases of 89, 63, 230, 38, and 656%, respectively. Overall, the findings of this research showed that the use of sepiolite in stressful conditions can be beneficial in improving the concentration of nutrients, especially Fe, Mg and Ca, and reducing sodium accumulation in cucumber.

Previous studies have shown that salinity and alkalinity stresses caused a reduction in growth of plants (Roosta, 2011). Sepiolite mineral has been found in different regions of Iran and its agricultural and industrial uses have been started (Galan, 1996). Although some researches have been done on the environmental applications of this mineral as an adsorbent, there is very little information about the use of calcium-enriched sepiolite in the plant culture environment. Therefore, considering the role of salinity and alkalinity in reducing the production of products and the characteristics of sepiolite clay, this research was conducted to investigate the effect of calcium-enriched sepiolite as a soil conditioner to reduce the adverse effects of salinity and alkalinity stresses on cucumber.

The studied sepiolite was obtained from a mine in Fariman and after being grinding it was saturated with calcium chloride. This research was carried out in the greenhouse of Vali-e-Asr University of Rafsanjan as a hydroponic culture in a medium containing perlite and Ca-enriched sepiolite. The experiments included three levels of sepiolite (0, 10% and 20% w/w) and four levels of stress (no-stress conditions as control, salinity stress by 70 mM sodium chloride, alkalinity stress by 70 mM sodium bicarbonate, and combined salinity and alkalinity stresses by sodium chloride 70 mM and sodium bicarbonate 70 mM). The treatments were arranged in a factorial way in the form of a completely randomized design with three replications. At the end of experiment, the plants were completely removed from the pots and the aerial and root parts were separated, and after washing with distilled water, they were dried at 70 ºC for 48 hours and then powdered. The total concentrations of Ca, Mg, Na, Cl, Zn, Cu, Fe and Mn in plants shoot and root were determined according to standard methods.

The results showed that the use of Ca-enriched sepiolite reduced the adverse effects of stress on the concentration of nutrients. In non-stressed conditions, the concentrations of Mn and Mg in the root and shoot increased due to 10% sepiolite application. The concentration of Ca in the root and shoot increased in all sepiolite-treated pots, and Ca-enriched sepiolite decreased Na concentration in the root and shoot. Under salinity stress, the concentration of Cu in the shoot, Fe and Ca concentrations in the root and Mn concentration in the shoot and root increased, but the concentrations of Zn and Mn in the root and shoot decreased due to 20% sepiolite application. Under alkalinity stress, the concentration of Cu in the shoot, Mn and Ca concentrations in the root, and Mg and Fe concentrations in the root and shoot increased while the Na concentration in the root decreased. Under the combined salinity and alkalinity stresses, the concentrations of Cu and Mn in the shoot, and Fe and Mg concentrations in the shoot and root increased.

Based on the results of this research, calcium-enriched sepiolite had favorable effects on the concentration of nutrients such as calcium, magnesium, and iron in cucumber plants, and by removing sodium from the reach of the plant, it reduced the adverse effects of salinity and alkalinity stresses of the culture medium. Therefore, calcium-enriched sepiolite can be suggested as an amendment under salinity and alkalinity stress conditions.

Waste tire rubber (WTR) contain significant amounts of zinc (Zn) and they are potential sources of Zn for plants. This study was carried out to investigate the effect of Zn-dissolving Pseudomonas isolates and WTR on growth characteristics and Zn and Fe concentrations of the corn plant. An experiment was conducted in a completely randomized design with factorial arrangement with three replications in a sterile sand -culture in green house condition. The experimental factors include Pseudomonas bacteria at six levels (without inoculation (C) and inoculation with five isolates (B1 to B5)) and Zn treatment from the WTR source at four levels of 0 (C), 100 (T1), 200 (T2) and 300 (T3) mg Zn per kg (equivalent to 0, 9, 18 and 27 g WTR per kg of sand respectively). The results showed that the main effects of the treatments on Photosynthetic performance index, chlorophyll content of leaves, Chlorophyll fluorescence and shoot dry weight were significant. The amount of each of these parameters increased in all bacterial and WTR treatments. The use of WTR (18 g/kg) along with inoculation of isolates increased all measured parameters compared to the control. Root dry weight and zinc concentration in shoots and roots, were affected by the interaction of treatments. The highest amount of plant dry weight was observed in B3+T3 treatment (2.14 fold increase compared to the control (. The concentration of zinc in the plant shoots was the highest in the B4+T3 treatment, which was 20 times higher than the control. The highest concentration of zinc in the root was observed in the presence of isolates B3 and B2 in WTR (18 g/kg) treatment which was 25 and 22 times higher than the control, respectively. The highest concentration of iron in the shoots and roots of the plant was related to the WTR (18 g/kg) treatment with the amount of 28.3 and 30.7 mg kg-1, respectively. The bacterial isolates increased the iron concentration of shoot compared to the control, but no significant difference was observed between the isolates.

The present study aimed to investigate the efficiency of silicate solubilizing bacteria in the release of elements of sepiolite. The greenhouse test was performed as factorial with completely randomized design with three repetitions. This experiment consisted of three bacterial strains (B7, B8, and D1) and pistachio (two cultivars Badami Riz Zarand and Qazvini) and four drought levels (including 90% (control), 75%, 60% and 45% of FC). The seedlings were fed with Hoagland's magnesium-free nutrient solution over a five-month growth period. The vegetative and biochemical traits of the seedlings were studied. The results showed that at the highest level of drought stress, application of strains B1 and B2 increased the rate of root Si uptake in Qazvini seedlings by 77% and 97%, respectively, and in seedlings of Badami Riz Zarand by an average of 2.75 times compared to non-drought stress conditions. Application of B7 strain increased Mg uptake in Qazvini seedlings from 6.91 mg per pot under non-drought stress conditions to 13.9 mg per pot at the highest level of drought stress. In Badami Riz Zarand, the application of the mentioned strain increased the uptake of Mg in the shoot at three stress levels of 75%, 60% and 45% of the field capacity by 74%, 67% and 66%, respectively, compared to non-drought stress conditions. Presence of these bacterial strains in symbiosis with plants will have a significant effect on the release of elements from minerals and its absorption by the plant and thus improve plant nutrition and change the mineral structure.

Remediation of heavy metals contaminated soils by plants is one of the most cost-effective and environmentally friendly methods. In some cases, useful soil microorganisms are used to increase the plants efficiency in heavy metal remediation. The aim of this study was to investigate the effect of rhizospheric pseudomonads on increasing the phytoremediation efficiency in copper (Cu)-contaminated soils. The first experiment was carried out in a completely randomized design in three replications with 11 plant treatments (Maize (Zea mays), sorghum (Sorghum bicolor), wheat (Triticum aestivum), canola (Brassica napus), Fennel (Foeniculum vulgare), Amaranth (Amaranthus), Salvia (Salvia officinalis), Zygophyllum (Zygophyllum), Ajwain (Trachyspermum ammi), alfalfa (Medicago sativa) and pumkin (Cucurbita)). The highest Cu concentration and uptake  were related to Zygophyllum with 173 mg kg-1 and pumkin with 222 µg pot-1, respectively. Five plants including pumpkin, maize, wheat, canola, and Zygophyllum were selected based on the highest Cu concentration and uptake of  for the second experiment. The second experiment was designed in a completely randomized design with two factors including plant types at five levels (pumkin, maize, canola, wheat and Zygophyllum) and three levels of bacteria (non-bacterial inoculation, Pseudomonas putida PA2 strain, Pseudomonas fluorescence PA3) in three replications. In this section, the shoots and roots dry weight; Cu concentration and uptake in shoots and roots, as well as the chemical changes of the Cu in the rhizosphere were investigated. The use of both strains of the bacteria significantly increased the dry weight, concentration and uptake of Cu in shoots and roots compared to the control. Among the plants, pumpkin had the highest uptake of Cu in shoots due to high biomass (90.2 µg pot-1) (the most effective in phytoextraction) and maize due to its high root weight had the highest Cu uptake (428 µg pot-1) (effective in high Phytostabilization). Investigation of the chemical forms of Cu in the rhizosphere showed that inoculation by PA2 and PA3 growth-promoting bacteria increased 41.9 and 37% of soluble and exchangeable forms of Cu respectively, and decreased the residual form of copper up to 7.05 and 6.41%. The overall results showed that the growth-promoting bacteria play an effective role in increasing the phytoremediation, especially the phytoextraction and pumpkin with the highest Cu uptake was the most efficient plant in the Cu phytoremediation in this study.

Cadmium, because of the long half a lifetime in the human and animal body and its toxicity, has great importance in agriculture. Today, plant growth-promoting rhizobacteria (PGPR) are used to increase the bioavailability and uptake of heavy metals in polluted soils. This study aimed to investigate the effectiveness of cadmium-tolerant fluorescent pseudomonads with inorganic phosphate solubilizing ability on the cadmium uptake by maize plants in contaminated soil. For this purpose, a greenhouse experiment was conducted in factorial based on a completely randomized design with four replications. Treatments were included four levels of bacteria (without bacteria (P0) and inoculation with three isolates P1, P169, P108) and four levels of time after planting (3, 6, 9, and 12 weeks). The soils were artificially spiked with cadmium (13 mg kg−1) as Cd(NO3)2. The results showed that the inoculation of maize with the selected isolates significantly increased shoot and root dry weights and shoot cadmium uptake in comparison to non-inoculated plants. The maximum shoot dry weight observed in plants inoculated with P169 and 12 weeks (31.22% more compared to non-inoculated plants). In the 12th week after planting, there was not any significant difference among P1, P108, and P169 isolates in shoot dry weights. P1 and P108 enhanced shoot dry weights by 23.81 and 22.21 percent in comparison to control, respectively. The maximum uptake of cadmium in plant shoot was found in inoculation with P169 and 12th week. In the 12th week, P169 increased cadmium uptake of the shoot by 150 percent in comparison to the control and 13.81 and 37.75 percent, compared to P1 and P108, respectively. Although all of the isolates used in the greenhouse experiment significantly increased cadmium uptake by maize plants but the effectiveness of P169 was more evident than other isolates.

  Salinity, especially NaCl, is one of the most important abiotic stresses which limits crop productivity in dry regions like Iran. Also, soil and water heavy metal pollution is increasing in developing countries, which may suppress crop yield. The adverse effect of salinity on crop growth may be affected by soil cadmium content and vice versa. Purslane is one of the oldest and the most salt tolerant plant species having medicinal and edible uses in arid climates. Little is known about growth response of purslane to combined effect of NaCl and cadmium in soils. The aim of this study is to investigate the interaction of NaCl and cadmium on vegetative and physiological characteristics, sodium (Na) and cadmium (Cd) uptake and accumulation in roots and shoots of purslane. This experiment was arranged as factorial based on complete randomized design with four replications and conducted in growth chamber with 25/18 °C temperatures. Factors included growth medium NaCl concentration at four levels (0, 23.1, 57.4 and 100.2 mM) and cadmium at five levels (0, 0.5, 1, 2 and 4 mg/l). Seeds of purslane (local ecotype of Jiroft) were sown in 1-litre plastic pots filled with coco peat-perlite (2:1) and were watered until full emergence and establishment. Then, seedlings were treated with Hoagland solution containing calculated amounts of NaCl and cadmium until 87 days afterward. Significant decrease in shoot biomass started from 23.1 mM NaCl and 2 mg/l cadmium. Also, leaf greenness index (SPAD value) decreased with increase in salinity in each cadmium level; however, when no cadmium was applied, SPAD did not significantly decrease up to 57.4 mM NaCl. Similarly, salinity had no significant effect on leaf relative water content (RWC), but in each salinity level, RWC decreased with increased cadmium level. On the other hand, tissue electrolyte leakage significantly increased with NaCl concentration, however, increase in Cd concentration had no substantial effect on it. Shoot and root Na content linearly increased with salinity, but in each salinity and Cd level, contents of Na in roots were significantly higher than those of shoot. Same results were observed for shoot and root Cd content. Shoot Na content was not significantly affected by Cd concentration in growth medium until 2 mg/l Cd and only 4 mg/l Cd significantly increased it. Although sodium chloride and Cd contamination decreased purslane growth, but our results suggest that considerable accumulation of Na and Cd in roots of purslane inhibits excess translocation of Na and Cd to shoot tissues and further growth inhibition

Quantity-intensity parameters provide practical information about potassium availability. Limited information about quantity-intensity relationships in Rafsanjan and Anar regions under pistachio orchards is available. So that this research was conducted to study the status and chemical forms of potassium using common extractants and also study the quantity-intensity relationships. For this purpose in 20 soil samples that were taken from Rafsanjan, Anar, Nough and Kabootarkhan, soil potassium was extracted using ammonium acetate, sodium acetate, 0.01M calcium chloride, 0.1 M nitric acid, 2M sodium chloride, water and boiling nitric acid extractants and chemical forms of potassium and their correlation with leaf potassium concentration were determined. Results showed that amount of soluble potassium in these soils is between 33.9-193.6, exchangeable potassium was in the range of 71.8-683.6 and nonexchangeable potassium was in the range of 250.1-1112.6 mg kg-1. None of these extractants had significant correlation with leaf potassium concentration of pistachio trees. Mineralogical analysis indicated that montmorilonite, illite, chlorite, kaolinite and paligorskite are dominant minerals in this region. Quantity-intensity relationships revealed that the potential buffering capacity (PBC) is in the range of 30.685-78.758, the rang of activity ratio in equilibrium (ARke) is 0.002-0.022 and the readily exchangeable potassium (DK) is in the range of 0.0885-1.66 in studied soils. DK parameter showed a significant correlation with soluble, exchangeable and nonexchangeable forms of potassium. ARke parameterwas correlated with soluble and exchangeable forms significantly but PBC parameter had no correlation with chemical forms of potassium and soil characteristics.

Siderophores are low molecular weight iron-binding ligands produced by aerobic soil microorganisms and some plants roots. They may also develop complexes with other metals such as Cd, thereby influencing the bio-availability, toxicity and mobility of Cd in the soils and aqueous environments. The main objective of this study was to investigate the effects of desferal siderophore (DFOB) on the adsorption of Cd on muscovite. The adsorption of Cd on muscovite was studied as a function of pH (Cd concentration: 5.0 mg L-1) in the range of 3.0-8.0, as a function of metal concentration (Cd concentration in the range of 1.5-10.0 mg L-1); this was done in the absence and presence of siderophore (DFOB concentration 250 μM) using a 24h batch equilibration experiment. The results of pH dependent experiments showed that the siderophore deceased the adsorption of Cd onto muscovite at pH ≥5. The results of the isotherms experiments also showed that the removal of Cd from solution was affected by siderophore in all equilibrium concentrations of Cd at both pHs. Siderophore decreased the adsorption of Cd by the mineral. The Freundlich and Langmuir isotherms described the equilibrium data satisfactorily. The values of Freundlich (KF) and Langmuir (KL) bonding constants were greater in the suspensions without siderophore, as compared to those containing siderophore, thereby indicating the low adsorption affinity of Cd on muscovite in the presence of the siderophore.

Nowadays, extensive attention has been paid to removal and remediation of heavy metals from polluted sites. Biosorption is a cost-effective method for removing heavy metals from aqueous solutions. In this study, biosorption of Cd has been examined by shrimp shell.
The adsorption of Cd on shrimp shell was studied as a function of pH (Cd concentration: 8.0 mg L-1) in the range of 3.0-8.0, and as a function of metal concentration (Cd concentration in the range of 15-100.0 mg L-1) using a 24h batch equilibration experiments. The amounts of Cd sorbed on the adsorbent were calculated from the difference between the metal concentration in the blank and equilibrium concentration of Cd in the solutions. Chemical species of Cd(II) in the solutions was also predicted using Visual MINTEQ, a computer code developed to simulate equilibrium processes in aqueous systems. Infrared spectrums of untreated and Cd-loaded adsorbent were obtained using a Fourier transform infrared spectrometer.
The results of pH dependent experiments showed that the percent removal of Cd on the sorbent increased with the increase of suspension pH. The experimental data showed that shrimp shell used in this study removed more than 95% Cd from solution at pH=7.5. The Freundlich and Langmuir isotherms were described satisfactorily equilibrium data. Maximum sorption capacity (qmax) of the sorbent was 5.1 mg g-1. Pseudo second order kinetic model provided a perfect fit for the kinetic data of Cd sorption onto shrimp shell. Biosorption kinetics of Cd consisted of two steps: An initial rapid step where adsorption was very fast. The second phase is the gradual biosorption stage before the Cd uptake reached equilibrium. The equilibrium was achieved in 30 min for initial metal concentration of 5 mg L-1 and in 240 min for initial metal concentration of 50 mg L-1 where 91 % and 92 % of Cd were adsorbed, respectively. Based on the estimates obtained by Visual MINTEQ, the Cd2 and Cd(OH) species were the dominant species present in solutions in pH ≤ 8.5 and pH≥ 8.5, respectively. Infrared spectrum analysis of adsorbent before and after adsorption showed that the N atoms of the amine functional groups played a major role in shrimp shell for adsorption of Cd.
Based on the equilibrium sorption and kinetic information obtained for Cd removal by this sorbent, it may be concluded that shrimp shell is an effective sorbent for Cd and may be considered for environmental remediation in future studies.

Plant inoculation with effective plant growth promoting and heavy metal resistant rhizobacteria is an efficient method to improve the phytoremediation efficiency and extraction of heavy metals from contaminated soils. With respect to this reason, astudy was conducted to isolate, identify and evaluate the growth stimulating traits of copper-resistant bacteria from a Cu-contaminated soil. Six rhizospheric soil samples of indigenous plants were collected in Sarcheshmeh Khatoonabad, Kerman province. After screening, six strains were selected. Phenotypic, biochemical and genetic identification data showed that five and one isolates were belong to Pseudomonas and Bacillus genera respectively. Then, the minimum inhibitory concentration of copper, siderophore production, auxin and hydrogen cyanide production, the ability to solubilize mineral phosphate in solid and liquid medium, the ability to solubilize Zn low soluble compounds in solid and liquid medium and production of ACC-deaminase were investigated. The results indicated that all of the isolates were resistant to various concentrations of copper. The maximum resistance to inhibitory concentration of copper was related to K4 and K5 strains at a concentration of 400 mg L-1 of copper. All of the strains were able to produce siderophore in CAS medium except for K6 strains and strain K5 was also the superior in siderophore production. Among the strains, K4 and K6 were not able to produce auxin. There was also a significant difference between auxin productions by isolates K1 with the other isolates, with the highest auxin production (2.07 mg L-1). The results also demonstrated that among the strains, only K4 strain was capable of producing hydrogen cyanide (degree: four=relatively high) and the other isolates were reported as non-production of hydrogen cyanide (degree: one). The results of Three Calcium Phosphate (TCP) solubilizing by isolates in PKV broth medium showed that K1, K2, and K3 strains had the most phosphorus solubility (706, 661 and 588 mg L-1) respectively and there wasn’t significant difference between them. The results demonstrated that K4 and K5 isolates with 0.910 and 0.850 halos to colony diameter had a significant difference with other isolates in solid medium containing ZnCO3 and the rest of the strains, K1, K2, K3 and K6 did not show the ability to solubilize the zinc carbonate as well. The solubilizing of solid zinc oxide in solid medium by K4 strain (halo:colony, 2.11) was the highest solubility of zinc oxide and K1, K2, K3 and K6 strains were not able to dissolve the zinc oxide in the solid medium. They did not show the ability to dissolve the low soluble zinc oxide nor the zinc carbonate compounds. K4 strain had the highest zinc carbonate solubility in the broth (12.5 mg L-1) and the highest solubility of zinc oxide in the broth was attributed to K4 strain (9.76 mg L-1). According to the results, these isolates can be used for enhancing phytoremediation efficiency of this element in contaminated soils.

In order to study the effects of nano-fertile fertilizer containing humic acid on uptake of nutrients of two lettuce (Lactuca sativa L.) cultivars in a nutrient film technique (NFT) system, a factorial experiment based on completely randomized design with four replications was conducted. The experiment consisted of two factors, the nano-fertile fertilizer (0, 500 and 1000 mg/L) and cultivar (Great Lake and Super salad). In this experiment, nutrient elements (K, P, Ca, Mg, Fe, Zn, Mn and Cu) concentration in plant shoots and roots were measured. Results showed that concentration of 1000 mg/L of nano-fertile fertilizer increased concentration of these nutrient elements in shoots and roots of the lettuce plants. But, in the treatment of 500 mg/L nano-fertile fertilizer, only Zn, K and Mg in shoots and Zn, K and Ca in roots were higher compared to control. Great Lake cultivar was better than Super salad cultivar in the uptake of Zn in shoots and Ca, Fe, Mn, Zn and Cu in roots. According to results of this experiment, concentration of 1000 mg/L of nano-fertile fertilizer containing 75% humic substances can have positive effects on improving uptake of nutrient elements in treated plants.

This study examined the adsorption of lead (Pb) ions from aqueous solution onto shrimp shell. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, equilibrium time, and different initial concentration of Pb(II) ions were evaluated. The results indicated that the pseudo-second-order kinetic model could describe the kinetics of Pb adsorption by the adsorbent. With increasing Pb concentrations from 100 to 1000 mgL-1, the amount of Pb adsorbed by shrimp shell increased from 9 mg g-1 to 90.2 mg g-1. Increasing suspension pH from 4 to 7, enhanced adsorption of Pb. Further increase in pH from 7 to 10 resulted in decreasing of adsorption of the metal ion. The average adsorption of Pb by the adsorbent at pH 6 and 7 was more than 95 percent. The Sips and Freundlich models well described the adsorption of Pb isotherms data. Infrared spectrum analysis of adsorbent before and after adsorption of Pb showed that the N atoms of the amine functional groups played a major role in shrimp shell for adsorption of Pb.

Soil contamination by heavy metals is a major concern throughout the world, due to persistence of metals in the environment and their toxicity and threat to all living organisms. Several strategies have been used to immobilize heavy metal ions in soils. Immobilization can be achieved by adding natural and synthetic amendments such as zeolites and organic materials. Because of large specific surface area, high cation exchange capacity (CEC), low cost and wide spread availability, zeolites are probably the most promising materials interacting with many heavy metal ions in contaminated soils and water. Organic amendments such as vermicompost contains a high proportion of humified organic matter (OM), may decrease the bioavailability of heavy metals in soil by adsorption and by forming stable complexes with surface functional groups, thus permitting the re-establishment of vegetation on contaminated sites. Recent studies showed that the co-application of zeolite and humic acids could be effective in reducing the available fraction of Pb in a garden polluted soil. Fractionation of heavy metals cations in amended polluted-soils is needed to predict elemental mobility in soil and phyto-availability to plants. Therefore, the objective of this study was to investigate the effects of co-application of zeolite and vermicompost on Zn redistribution in a contaminated soil.
Material and A contaminated soil was collected from the top 20 cm in the vicinity of zinc mine in Zanjan province, western north of Iran. The soil sample was air-dried, passed through 2-mm sieve and stored at room temperature. The soil sample was thoroughly mixed to ensure uniformity. Sub-samples were then digested using the hot-block digestion procedure for total Zn concentration. The experiment was conducted under greenhouse condition. The polluted soil was put in polyethylene pots and mixed well vermicompost and zeolite at the rate of 0, 50 and 100 g kg-1 soil. The treatments were evaluated in a 3 × 3 factorial design and were arranged in a randomized block design with three replications. After incubation for 45 days, five seeds of corn were sown in each pot. After germination the seedlings were thinned to 3 per pot. Plants were grown for 2 months under control conditions. After the corn had been harvested, soil samples were air-dried, and analyzed for pH, cation exchange capacity (CEC), and electrical conductivity (EC). Chemical fractionations of Zn in soils collected after the pot trial were investigated using the procedure of Salbu et al. (1998). This procedure subdivides the heavy-metal distribution into an water-extractable笗Ⅺ砞榹 fraction, a form bound to carbonates, a form bound to Fe and Mn oxides, a form bound to organics, and a residual form. An analysis of variance was used to test significance (P≤0.05) of treatment effects and Duncan multiple range test (P≤0.05) was used to compare the means (SAS, 2002).
Soil pH gradually decreased with application of both vermicompost and zeolite amendments. This may be due to degradation of organic matter and releasing of organic and inorganic acids such as carbonic, citric and malic acids as well as H produced from mineralization of nitrogen in the organic matter. Electrical conductivity (EC) of soils increased with increasing amounts of vermicompost and zeolite applications. The highest EC was observed in pots containing 10% w/w zeolite and 10% w/w vermicompost. Addition of zeolite significantly increased soil CEC. The overall distribution of Zn in different fractions was in the sequence residual (38.6%)> Fe and Mn oxides bound (31.0 %) > carbonated (21.6%)> organic (4.3%)≈exchangeable 솫 soluble (4.4 %). The application of vermicompost significantly decreased concentration of Zn in water笗Ⅺ砞榹 fraction as compared to the control soil. Although singly zeolite amendment had not significant effect on water笗Ⅺ砞榹 Zn concentration, this form decreased significantly with co-application of vermicompost and zeolite. This may be due to redistribution of Zn from this form to less available forms (e.g. organic and residual fractions). The addition of vermicompost had not significant effect on the carbonated fraction of Zn, whereas co-application of zeolite and vermicompost significantly decreased concentration of Zn bound in carbonates. Singly zeolite and co-application of amendments decreased the concentration of Zn in Fe and Mn oxides bound. Although singly compost and zeolite amendments increased concentration of Zn bound to organics, this form decreased furthest with co-application of them. Zeolite and vermicompost alone had not significant effect on mobility factor (MF) of Zn over the un-amended soil. Co-application of vermicompost and zeolite to polluted soil resulted in a significant decrease in MF values of Zn compared to control.
Co-application of vermicompost and zeolite to polluted soil resulted in redistribution of Zn from available forms (exchangeable 솫 soluble) to less available form (e.g. organic), thus may be useful for the immobilization of Zn from polluted sites.

The mobility, bioavailability and environmental fate of heavy metal ions in soil are controlled by sorption onto soil minerals and solid organic matter. The sorption is strongly affected by the presence of various low-molecular-weight organic acids. The main objective of this study was to investigate the effects of oxalic acid on sorption of Cd on clay fraction of a soil.
The sorption of Cd on clay was studied as a function of pH and time of equilibrium (Cd concentration: 0.045 mM) in the range of 6-9.5, and as a function of metal concentration (Cd concentration in the range of 0.013-0.089 mM) in the absence and presence of oxalic acid with a fixed concentration of 500 μM at room temperature (23 ± 2 °C). The amounts of Cd sorbed on the adsorbent were calculated from the difference between the metal concentration in the blank and equilibrium concentration of Cd in the solutions.
The results of pH-dependent experiments showed that the oxalic acid decreased sorption of Cd onto the sorbent at all solution pHs. Experimental and modeling data from our kinetic reveal that the pseudo-second-order kinetic model gave the best fit. The Langmuir sorption model describes the interaction between Cd and the clay materials better than the Freundlich model. The value of Langmuir (KL) bonding constant was greater in suspensions without oxalic acid (26.6 Lg-1) as compared to suspensions containing this ligand (15.2 Lg-1). Also, the value of Freundlich (KF) bonding constants was greater in suspensions without oxalic acid (1.2 Lg-1) as compared to suspensions containing this ligand (1.8 Lg-1). These values are indication of low tendency of Cd for sorption on the clay surfaces in the presence of oxalic acid. In order to interpret the effect of oxalate on the sorption behavior of Cd onto the sorbent, knowledge of Cd speciation is essential. Species activities were estimated using the PHREEQC code. In the absence of oxalate, the predominant Cd(II) species is Cd2 over the pH range 3.0–9.0. In the presence of oxalate, Cd2 and Cd-Oxalate species were the major solution Cd(II) species at pH ≤10 . The formation of soluble complex of Cd-oxalate may be responsible for the inhibition of Cd sorption by the sorbent.
In general, our results demonstrate that the oxalate could have negative effects on Cd sorption to clay fraction of soils. Thus, it may play an important role in Cd availability and transport in soil.

Soil salinity and Zn deficiency are among the most important limiting factors for growth and yields of pistachio trees in many regions of Iran, especially in the Rafsanjan area. The use of plant growth promoting rhizobacteria (PGPR) is new strategies to reduce destructive effects of salinity and improvement of nutrient availability. This study investigated the interactive effect of the fluorescent pseudomonads rhizobacteria and Zn on the fractionation and availability of Zn in the rhizosphere soil and uptake of Zn by shoot of pistachio seedlings (cv. Badami) under salinity condition.
Material and A greenhouse experiment was conducted in a factorial experiment based on completely randomized design with three replications in order to evaluate the interactive effect of fluorescent pseudomonads rhizobacteria (pf0 (non-inoculated control), pf1, pf2 and pf3) and Zn application (0 and 5 mg Zn kg-1) on the Zn fractionation in the different levels of soil salinity {0 (1.46 dS m-1), 1000 (7.32 dS m-1) and 2000 (12.0 dS m-1) mg NaCl kg-1 soil} and its relationship with concentration and uptake of Zn in the pistachio seedlings (Pistacia Vera L. cv. Badami) shoot.
The results indicated that salinity and inoculation with fluorescent pseudomonads increased the DTPA- extractable Zn (DTPA-Zn) content and the forms of water soluble plus exchangeable (WSEXC) Zn, carbonate-bound (CA) Zn and organic matter-bound (OM) Zn, while decreased Fe-Mn oxide-bound (FeMnOX) Zn and residual (RES) Zn in the rhizosphere soil. Inoculation by fluorescent pseudomonads increased the DTPA-Zn, WSEXC-Zn, CA-Zn and OM-Zn contents by 52, 26, 29 and 35%, respectively but decreased FeMnOX-Zn and RES-Zn contents by 24 and 3 %, respectively. Also, Zn application significantly increased all forms of Zn (except residual form) in the soil. The results showed that salinity reduced the concentration and uptake of Zn in the pistachio seedlings shoot, while inoculation with fluorescent pseudomonads and treatment with Zn incrased its contents at all salinity levels. However, the combined application of the fluorescent pseudomonads and Zn were more effective. There was a positive and significant correlation between Zn uptakes by shoot and DTPA-Zn, WSEXC-Zn, CA-Zn and FeMnOX-Zn. As well as, soil salinity and inoculation by fluorescent pseudomonads reduced pH value of rhizosphere soil from 7.73 to 7.46 and 7.59, respectively.
The results showed that soil salinity increased Zn availability in the rhizosphere soil, while reduced the concentration and uptake of Zn by pistachio seedlings shoot due to reduce of root volume, water availability and high content of Na ion. Thus, the use of superior isolates-especially Zn solubilizing bacteria- can effectively increase the availability of Zn in soil and uptake of Zn by plants through increasing root growth. However, WSEXC-Zn, CA-Zn and FeMnOX-Zn could be used as available fractions of pistachio seedlings.

This experiment was conducted to evaluate the effect of vermicompost, pistachio kernel and shrimp shell on the immobilization and availability of Cd, Pb and Zn in corn in polluted soils. Treatments consisted of two levels of pistachio kernel, shrimp shell and vermicompost (5 and 10 % w/w). In control treatment, no amendment was added to the soil. The experiment was carried out as a completely randomized design with 3 replications. Plants grew for two months in the greenhouse. Then, all the plants were harvested and their shoots and roots were separated, washed with distilled water and oven dried at 65 °C to a constant mass. The measured characteristics were dry weight of shoots and roots, leaf area, greenness index, chlorophyll fluorescence, maximal quantum yield of PS photochemistry (Fv/Fm), performance index (PI), and total concentrations of Cd , Pb and Zn in shoots and roots. Results showed that plant growth parameters (dry weight of shoots and roots, leaf area) and photosynthetic characteristics (chlorophyll fluorescence, Fv/Fm, and PI) were higher in plants grown in vermicompost and pistachio kernel treatments as compared to those grown in control. Plants died in shrimp shell treatment after two weeks. The concentration of Cd, Zn and Pb in shoots and roots of plants grown in vermicompost and pistachio kernel treatments were lower than those grown in control.

Successful phytoremediation of metal-contaminated soils largely depends on their bioavailability in soil. Samples of a contaminated soil with elevated concentration of Zn were applied in the pots to evaluate the interactive effects of DFOB siderophore (0, 70 and 140 μM kg−1) and metal tolerant bacterial inoculation (p0, p15, p18, and p19) on Zn accumulation in corn and metal speciation and sequential fractions in soil. Results indicated that bacterial inoculation increased Zn concentrations in corn shoot. Addition of DFOB (140 μM kg−1) to pots of the soil which was inoculated with p15 isolate significantly enhanced Zn concentration in roots as compared to control. The uptake of Zn by shoots was increased in pots inoculated by bacterial isolates compared to those in the un-amended soils. Ligand addition significantly enhanced the concentration of DTPA-extractable Zn. Also co-application of DFOB and bacterial inoculation significantly decreased Zn bound to carbonates fraction and increased water soluble Zn concentration. Based on the results of this study, it can be concluded that co-application of DFOB and metal tolerant bacteria are efficient in increasing the bioavailability of Zn when expressed relative to the control treatment, which might be of great significance for the successful phyto-extraction of Zn-polluted soils.

Knowledge about factors affecting boron adsorption by minerals commonly found in soils of arid and semiarid areas may help us in management and reclamation of boron polluted soils. The main objective of this study was to investigate the adsorption characteristics of biotite for boron in batch experiments. The adsorption of boron on the adsorbent was studied as a function of pH in the range of 6.5-9.0 with two boron concentrations of 5 mg L-1 and 15 mg L-1. To study the effect of cations and ionic strength on boron adsorption, Mg(NO3)2, Ca(NO3)2 and NaNO3 background electrolytes at three concentration levels (0.03, 0.09 and 0.18 M) were used. Adsorption isotherms were derived by adsorption of boron from solutions containing different concentrations in the range of 1-15 mgL-1 using a 24h batch equilibration. Results showed that the amount of boron adsorption increased with increasing equilibrium pH and ionic strength of solution. Boron adsorption increased from 1.28 mmol kg-1 to 2.64 mmol kg-1 as the ionic strength of solution increased from 0.03 M to 0.18 M. Greater adsorption was observed in the presence of Ca2 and Mg2誉 as compared with Na ions at the same concentrations. Adsorption isotherms of boron were well described by the Freundlich and Langmuir isotherms. Maximum boron adsorption capacity (qmax) of biotite was obtained to be 27.2 mmol kg-1. The experimental data showed that less than 6% of initial boron concentration was adsorbed by biotite. Thus, it seems that this mineral has not a reasonable adsorption capacity for B.

Boron is one of the eight essential micronutrients required for plant growth and development. The optimal concentration range (between deficiency and phytotoxicity) for boron is narrower than for other plant essential nutrients. Generally, irrigating water containing concentrations of B greater than 1 mg L-1 would be detrimental for most plants. Although, there are a large number of different studies on the removal of B ions from aqueous solutions using different adsorbents, every special adsorbent material requires individual research. Information about the chemical behavior of muscovite for boron is very limited. Therefore, the objective of this study was to investigate boron adsorption on muscovite as a function of solution pH, ionic strength of the background electrolyte, kinds of cation, and initial boron concentration. The muscovite sample was obtained from a mine near Hamadan city in western Iran. It was powdered in a mortar and sieved before sorption experiment. Boron adsorption experiments were performed in batch systems using 15 mL polyethylene (PE) bottles in 0.01 M Ca(NO3)2 electrolyte solution at a adsorbent concentrations of 10 g L-1, and at room temperature (23±2 ◦C). All samples were prepared in duplicate. Blank samples (without adsorbent) were prepared for all experiments. For pH dependent B adsorption, aliquots of B stock solution (1000 mg L−1) were added to obtain initial B concentrations of 5 and 15 mg L-1. The pH of the solutions were adjusted to values of 6.8, 7.7 and 8.8 by adding negligible predetermined volumes of 0.03M NaOH or 0.03M HNO3 solution. To study the effects of kinds of cation on boron adsorption, samples of adsorbent (0.1 g) were mixed with 10 mL background electrolyte solutions (0.01M Ca(N 3)2, Mg(NO3)2 and NaNO3) in 15 mL centrifuge tubes. Then, predetermined amount of B were added to the centrifuge tubes to obtain final concentrations of 5 mg L-1 B. For determination of boron adsorption isotherm, after 10 ml 0.01 M of Ca(NO3)2 was transferred into 15 ml centrifuge tubes, 0.1 g sample of muscovite was added to obtain adsorbent concentration of 10 g L-1. Then a predetermined amount of boron from the stock solution was added to give final concentration range between 1 and 15 mg B per liter. Initial pH of the solution was adjusted to 8.2 ± 0.1 by predetermined amount of 0.03 M NaOH solution. Suspensions were then shaken for 24h. At the end of equilibrium time, final pH was measured in the suspensions and the tubes were then centrifuged for 10 min at 5000 g. Half of the supernatant volume (5 mL) was pipetted out from each tube and then B in the supernatants were measured using the colorimetric Azomethin-H method. The amount of B adsorbed on the adsorbent was calculated as the difference between the B concentration in the blanks and the concentration in the solution after equilibration. Chemical species in the solutions were also predicted using Visual MINTEQ, a chemical speciation program developed to simulate equilibrium processes in aqueous systems. The effect of pH on the amount of B retained depended on the initial B concentration. The amount of boron adsorption increased with increasing equilibrium pH. Boron adsorption on muscovite increased with increasing ionic strength. Greater adsorption was observed in the presence of Mg2+ as compared with Ca2+ at the same ionic strength. Calculations using Vminteq showed that the concentration of Mg-borate ion pairs (MgH2BO3 +) were higher than the concentration of Ca and Na-borate ion pairs (CaH2BO3 + and NaH2BO3°). It thus seems that the much greater loss of B from solution observed in the Mg system was caused by Mg-borate ion pair adsorption. Sorption isotherm of B were well described by the Freundlich, Langmuir and Sips models but the Sips sorption model describes the interaction between B and the mineral better than the Langmuir model. On the basis of n value of Freundlich model, adsorption isotherm of boron on muscovite was classified as L-type (n≤ 1). This kind of adsorption behavior could be explained by the high affinity of the adsorbent for the adsorptive at low concentrations, which then decreases as concentration increases. Maximum sorption capacity (qmax) was obtained to be 13.98 mmol kg-1 for muscovite. The experimental data showed that less than 5% of initial boron concentration was adsorbed by muscovite, thus this mineral has not a reasonable adsorption capacity for B.