Soil science
J. Sadeghi; A. Lakzian; A. Halajnia; M. Alikhani Moghaddam
Abstract
Introduction
The rapid growth of technology, industry, and development of cities has led to an increase in heavy metal pollution in freshwater sources and greywater across the world. The use of different adsorbents in order to remove some heavy metals from aquatic environments is a topic that has been ...
Read More
Introduction
The rapid growth of technology, industry, and development of cities has led to an increase in heavy metal pollution in freshwater sources and greywater across the world. The use of different adsorbents in order to remove some heavy metals from aquatic environments is a topic that has been addressed many times in different studies. However, the use of inexpensive absorbents with high adsorption capacity and high efficiency is the priority of many researchers especially when they are discussing the removal of heavy metals from the aquatic environment. Nanomaterials by having exceptional properties such as high efficiency of adsorption, high specific surface area, and fast adsorption can be used to remove metal pollutants from aquatic environments. Carbon dot (CD), among various nanomaterials (carbon-based nanomaterials (CNM), including carbon nanotubes (CNTs), graphene) are suitable adsorbents for heavy metals removal due to their specific surface area and many binding sites. Carbon dots are nanoparticles that lack a specific dimension and fall under the category of carbon nanomaterials, measuring over 10 nm in size. They possess various qualities, including being environmentally friendly, simple to create, highly compatible with living organisms, stable, and capable of switching emission on and off based on the excitation wavelength. Additionally, they can be customized for specific uses due to their high carbon content, which can reach up to 99.9%. These characteristics have generated significant interest among researchers in various fields. In this study, the influence of the fungal carbon dots on the adsorption capacity and kinetics, isotherms, and thermodynamics of lead was investigated.
Materials and Methods
Alternaria alternata provided by the Department of Plant Protection at Ferdowsi university of Mashhad. It was recultured and fungal exopolysaccharide was extracted and then was converted into carbon dot using the hydrothermal method. Fungal exopolysaccharide autoclaved in a Teflon container at a temperature of 200 °C. Lead adsorption of synthesized fungal carbon dots was investigated. Lead adsorption tests by fungal carbon dots were performed in laboratory conditions. Lead concentrations (100, 200, 300, 400, 500, 750 and 1000 mg L-1), contact time (5, 10, 15, 20, 25, 30 and 60 minutes), pH (2, 4, 6, 7, 8, 9, 10 and 11), amount of carbon dots (nanosorbent) (50, 100, 200, 300, 400, 500, 750 and 1000 mg), ionic strength of the solution (0.1, 0.01 and 0.001 M potassium chloride) and solution temperature (25, 30, 35, 40 and 45 °C) was considered for kinetic tests. The data obtained from the kinetic tests were fitted using non-linear regression analysis using Statistica 7.0 software with the kinetic models of intraparticle diffusion, Lagergren (pseudo-first order) and pseudo-second-order. Thermodynamic results were calculated from the data of lead adsorption isotherms at temperatures of 25, 35 and 45 °C. Thermodynamic parameters to analyze the effect of temperature on metal adsorption, such as free energy change, enthalpy change and entropy change, were estimated using thermodynamic equations.
Results and Discussion
The initial lead concentration had a great effect on the adsorption rate it by carbon dot, and the highest and lowest percentage of lead adsorption with values of 90.65 and 44.2% were observed in two concentrations of 300 and 1000 mg L-1 of lead, respectively. With the increase of pH up to 8, the amount of lead adsorption by fungal carbon dot increased significantly. However, with further increase in pH, this trend was reversed and the amount of adsorption decreased. The results showed that lead adsorption by carbon dot increased with the decrease of potassium chloride molarity. By increasing the amount of carbon dot in the solution, the amount of lead adsorption increased, and the highest adsorption was observed at the concentration of 300 mg L-1 of carbon dot. The results of the experiment also showed that with increase in temperature, the adsorption rate increased at first and then decreased. Based on these results, as the contact time between the absorbent and lead increased, the amount of adsorption by the carbon dots also increased. The maximum adsorption was observed at 25 minutes, which was considered the equilibrium time. As shown in the results, the pseudo-second-order model shows the kinetics of Pb adsorption better than the two pseudo-first-order models and intraparticle diffusion. In this model, R2 values are between 0.9989 and 0.9994, and Qe is almost equal to the equilibrium value. According to these results, the decrease of values DG° with the increase in temperature means that the adsorption of lead increases with the increase in temperature, which shows that the adsorption process is more favorable with the increase in temperature, or in other words, it is a spontaneous reaction. Also, the positivity of the reaction enthalpy value (DH°) shows the endothermic nature of the adsorption process. The positivity of the entropy value (DS°) indicates the increase of disorder of the system between the adsorbent material and the solution during the process of lead adsorption by the carbon dot.
Conclusion
In total, the results showed that the carbon dot is a very good absorbent for removing lead from the water environment. In the experimental condition when the initial concentration of lead was 300 mg L-1, temperature was 25 °C, adsorbent concentration was 0.3 g L-1, reaction time was 25 minutes, and pH 8, the amount of lead adsorption increased significantly. It seems that fungal carbon dot is a safe and relatively cheap adsorbent and suitable for removing lead metal from the solution environment.
Soil science
J. Al-Jomah; A. Halajnia; A. Lakzian; A.R. Astaraei
Abstract
Introduction
Saline soils resulting from natural and/or anthropogenic processes are very diverse and widely distributed under all climates. Soil salinity as a serious environmental problem has negative effects on plant growth and development in arid and semi-arid as well as humid regions. Since increasing ...
Read More
Introduction
Saline soils resulting from natural and/or anthropogenic processes are very diverse and widely distributed under all climates. Soil salinity as a serious environmental problem has negative effects on plant growth and development in arid and semi-arid as well as humid regions. Since increasing global food security is a fundamental goal to feed the growing world population, it is necessary to develop suitable and efficient techniques for the rehabilitation of salt-affected soils and their exploitation. Chemical fertilizers are usually used to provide nutrients required for plant growth in order to increase crop yield, but application of these chemical components has negative environmental effects and reduces the quality of soils and agricultural products. The use of beneficial microorganisms (bacteria and fungi) as fertilizers and biological amendments has a high potential to improve productivity in saline soils. The aim of this study was to investigate the effect of using Acidithiobacillus bacteria along with mycorrhiza on the production of some photosynthetic and biochemical metabolites in maize under salt stress and comparing it with control conditions.
Materials and Methods
To perform this experiment, a surface soil sample was collected from a depth of 30 cm from the campus of Ferdowsi University of Mashhad, and some physical and chemical properties of the soil were measured by usual laboratory methods. To prepare saline soil a mixture of four compounds MgSO4.7H2O, Na2SO4, NaCl, and CaCl2. 2H2O were used. The mycorrhizal fungus (Funneliformis mosseae) and mesophilic Acidithiobacillus bacteria species two types of bacteria, Acidithiobacillus thiooxidans PTCC No: 1692 (DSM 504) and Acidithiobacillus ferrooxidans PTCC No: 1646 (DSM 583), were purchased from Turan Biotechnology Company (Semnan Science and Technology Park) and Iran Microbial Scientific and Industrial Research Center (PTCC), respectively. In this research, the effect of biological treatments including: two levels of mycorrhiza (inoculation and non-inoculation), two levels of salinity (0.96 and 6 d/m) and four levels of Acidithiobacillus control (C), Acidithiobacillus thiooxidans (T), Acidithiobacillus Ferrooxidans (F), Acidithiobacillus thiooxidans and Ferrooxidans (T+F) were compared with each other on some photosynthetic and biochemical characteristics of Zea mays under greenhouse conditions in the form of a completely randomized design with factorial arrangement with three replications. 10 gr of salt mixture (this amount of salt was obtained to reach electrical conductivity of 6 in the pre-experiment) was added to 5 kg of soil and the soil moisture of the pots was kept for one month in the field capacity. Bacterial treatments were inoculated with 30 mL of cell suspension per pot (approximately 107 CFU mL-1). In the simultaneous use of two bacteria, 15 ml of each bacterial cell suspension (15+15) was added to each pot. Single-cross 704 variety of maize was grown in pots and soil moisture was maintained during the growth period in the field capacity by weighing. Chlorophyll a, b and carotenoid, concentrations of flavonoids, anthocyanins and proline and electrical leakage were measured in fresh leaf samples (third leaf on the stem).
Results and Discussion
The results showed that salinity decreased the percentage of root colonization and chlorophyll a and b content in leaves. Salinity decreased chlorophyll a, b and carotenoid in leaves by 27.9, 68.42% and 50%, respectively. Salinity increased proline concentration (42.62%), electrolyte leakage (33.30%), anthocyanins concentration (96.36%) and leaf flavonoids (84.73%) compared to control soil. Inoculation with mycorrhiza compared to no inoculation had a remarkable and significant effect on all investigated parameters in both saline and control soils. In saline soil, mycorrhizal inoculation reduces electrolyte leakage (56.75%) and increases chlorophyll a (2.3 times), chlorophyll b (6.6 times), carotenoid (1.3 times), proline concentration (24.39%), anthocyanins amount (24.07) and flavonoids (20.4%) in the plant. The effect of bacterial treatments on the investigated parameters in plants inoculated with mycorrhiza was greater than non-inoculated treatments. The effectiveness of the simultaneous application of both bacteria was greater than the effect of each of them alone. In saline soil, simultaneous inoculation of mycorrhizae with both bacteria species reduces electrolyte leakage (14.72%) and increases chlorophyll a (39.80%), chlorophyll b (106%), carotenoid (50%), proline concentration (10.12%), the amount of anthocyanins (14.17%) and flavonoids (4.06%) compared to mycorrhiza treatment alone. The results showed that these bacteria can probably be considered as helping mycorrhizal bacteria.
Conclusion
The objective of this study was to examine the impact of simultaneous inoculation of mycorrhizae and Acidithiobacillus bacteria on select photosynthetic and biochemical metabolites of maize subjected to salinity stress conditions. Confirming the results of other studies, the results of this research also showed the clear and distinct effect of mycorrhiza on increasing chlorophyll and producing metabolites effective in increasing plant resistance to salt stress. In addition, the results showed that although the use of each species of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans alone was effective on the measured parameters in both saline and control soils, the simultaneous inoculation of both Acidithiobacillus bacteria species and mycorrhiza had the greatest effect on increasing chlorophyll, production of proline, anthocyanins and flavinoids and reducing electrolyte leakage and as a result, increasing tolerance to salt stress. In other words, these bacteria can be considered as mycorrhiza helper bacteria, whose activity can improve the function of mycorrhiza. On the other hand, mycorrhiza symbiosis may have increased the efficiency of these bacteria by changing the soil conditions and the environment around the roots. However, further greenhouse and field experiments with other plant species are necessary to confirm these findings.
Soil science
S. Arabteymori; A. Halajnia; A. Lakzian; F. Nikbin
Abstract
Introduction Surfactants as surface-active substances with combined hydrophobic and hydrophilic properties are widely used in various fields. In soil remediation processes these substances can be used to increase the availability of organic and inorganic contaminants to improve microbial decomposition ...
Read More
Introduction Surfactants as surface-active substances with combined hydrophobic and hydrophilic properties are widely used in various fields. In soil remediation processes these substances can be used to increase the availability of organic and inorganic contaminants to improve microbial decomposition of organic pollutants or heavy metals adsorption. In recent years, researchers have been seeking to produce and use surfactants that are more environment friendly. In this regard, produced biosurfactants by microorganisms are of special importance due to their environmental benefits. Microorganisms produce a wide range of biosurfactants. Biosurfactants are extracellular compounds that can combine with metals such as zinc, copper, and cadmium and can increase the solubility of these metals and reduce their toxicity. Negatively charged anionic biosurfactants such as rhamnolipids and lipopeptides can increase heavy metals availability by combining to metals and changing the properties of soil solution. In this study, the effect of surfactant application from Pseudomonas putida and Bacillus subtilis and some chelators include sodium citrate, humic acid and Na2-EDTA on soluble cadmium in a contaminated calcareous soil was investigated.Materials and MethodsThis study was conducted as factorial in a completely randomized design in laboratory conditions at several steps separately. A calcareous soil sample was contaminated with 15 mg kg-1 cadmium from the source of Cd (NO3)2. Contaminated soil incubated for 4 weeks at field capacity. Acid deposition method was used for surfactant extraction from culture medium of Pseudomonas putida KT-2440 and Bacillus subtilis 1795. The structure of extracted biosurfactants was investigated by FTIR. Equilibrium time was obtained by determining the amount of soluble cadmium at times 6, 12, 24, 36, 72 hours by adding 1mM sodium citrate, humic acid and Na2-EDTA to the contaminated soil (ratio of 1 to 5 soil to solution).The concentrations of 0, 0.1, 0.25, 0.5, 1 and 2 mM of humic acid, sodium citrate and Na2-EDTA were used to determine the appropriate concentration of each chelator. To investigate the interaction of chelators and biosurfactants on soluble cadmium, an experimental was conducted as a completely randomized design with factorial arrangement design. Experimental treatments consisted of three types of chelating agents (sodium citrate, humic acid, Na2-EDTA and control), two types of surfactants from Pseudomonas putida and Bacillus subtilis, and five concentration levels of the biosurfactants (0, 25, 50, 100 mg L-1).Results and DiscussionThe highest amount of soluble cadmium (11.59 mg L-1) was observed in Na2-EDTA treatment at 72 hours, which was significant compared to the other treatments. The lowest amount of soluble cadmium was obtained through application of sodium citrate (0.205 mg L-1) at 36 hours. In all studied concentrations, Na2-EDTA had the greatest effect and sodium citrate had the least effect on soluble cadmium. While the use of Na2-EDTA at all concentrations caused a significant increase in soluble cadmium, sodium citrate had no significant effect on soluble cadmium at studied concentrations. Humic acid at concentrations higher than 0.5 mM significantly increased the soluble cadmium. Increasing the concentration of humic acid and citrate from 1 to 2 mM did not show any significant impact on soluble cadmium. At all levels of biosurfactant application, Na2-EDTA and humic acid caused a significant increase in soluble cadmium concentration. In control and sodium citrate treatments, application of biosurfactants did not cause significant difference in the concentration of soluble cadmium. The highest amount of soluble cadmium was obtained as a result of the application of Bacillus subtilis surfactant and Na2-EDTA. However, increasing the concentration of Bacillus subtilis surfactant from 25 to 100 mg L-1 had no significant effect on increasing the efficiency of Na2-EDTA. Pseudomonas putida surfactant had no significant effect on soluble cadmium in Na2-EDTA application. While in humic acid treatment, the application of the Pseudomonas putida surfactant at the highest concentration (100 mg L-1) increased the concentration of soluble cadmium. Using Bacillus subtilis surfactant did not have effect on soluble cadmium in application of humic acid.ConclusionAmong the studied chelators (sodium citrate, humic acid and Na2-EDTA), Na2-EDTA had the greatest effect on soluble cadmium. While sodium citrate had no significant effect on soluble cadmium. Surfactants from Pseudomonas putida and Bacillus subtilis had different effects on increasing the efficiency of studied chelators and soluble cadmium in the studied soil. In Na2-EDTA and humic acid application, surfactant from Bacillus subtilis at a concentration of 25 mg L-1 and surfactant produced by Pseudomonas putida at a concentration of 100 mg L-1 had a significant effect on soluble cadmium, respectively. It seems using biosurfactants and chelators on increasing soluble cadmium in soil can be useful for phytoremediation purposes to increase its uptake by plant. However, further research is needed.
Soil science
T. Valizadeh; A. Lakzian; A. Halajnia; M. Mazhari
Abstract
Introduction: The deficiency of phosphorus has attracted a lot of attention as one of the most important nutrients for agricultural plants especially in calcareous soils. However, in some soils, organic phosphorous containing 80 percent of total phosphorus in some soils but in most cases, that form of ...
Read More
Introduction: The deficiency of phosphorus has attracted a lot of attention as one of the most important nutrients for agricultural plants especially in calcareous soils. However, in some soils, organic phosphorous containing 80 percent of total phosphorus in some soils but in most cases, that form of phosphorus is not available for plant uptake. The availability of phosphorus from both organic and inorganic sources by phosphate-solubilizing microorganisms (PSMs) as bio-inoculants are promising substitutes for chemical fertilizer and other agrochemicals amendments. Both arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) play a key role in providing phosphorus for agricultural plants. Among several phosphate-solubilizing fungal isolates, Aspergillus sp. is able to solubilize calcium phosphates by secreting various organic acids, e.g., oxalic and formic acids, and producing phytase enzyme. The present study aimed to evaluate the ability of different strains of Aspergillus for phytase production. The second aim of this study was the purification and application of purified phytase and its efficiency in the phosphorus availability from hexaphosphorylated inositols.Materials and Methods: Two separate experiments were carried out in two different stages. In the first one phytase was isolated from three strains of Aspergillus (Aspergillus niger provided by the department of plant protection, Agricultural college, Ferdowsi University of Mashhad), Aspergillus flavus, and Aspergillus fumigatus strains were collected from the Iranian biological resources center, Tehran). All Isolates were recultured on PDA (potato dextrose Agar) medium for 5 days at 30 oC in an incubator. Quality evaluation of phytase production by three strains of Aspergillus tested using hydrolysis of phytate sodium on PSM (phytase screen medium) medium. Solubility index was calculated for all three strains (Solubility index = (Colony diameter + Hallow diameter)/ Colony diameter). Phytase production was carried out on fermentation media (Shieh and Ware 1968) but starch was substituted by dextrin. Fermentation media inoculated by fungal strains for 14 days at 30 oC. Fermentation media was centrifuged (10,000 g) for 30 minutes and supernatant was collected. Purification of phytases was done against Tris-HCl 25mM, pH=7.2 for 12 hours. Phytase activities were evaluated in a completely randomized design with three replications. Then purified phytase from three Aspergillus strains was applied in a pot experiment using a completely randomized design with the factorial arrangement and three replications. The experimental factors included two levels of hexaphosphorylated inositols (and 50 mg/kg) and four types of phytase (Control, phytase isolated from Aspergillus niger, Aspergillus flavus, and Aspergillus fumigatus. In the greenhouse experiment, the effects of different phytase types on phosphorus availability from sodium phytate (hexaphosphorylated inositols) and phosphorus uptake by maize plant was evaluated. Corn plants (Zea maize 704 single cross) were grown in 5 kg pots at 70 % of water holding capacity for 60 days. Plant height, root dry weight, shoot dry weight, phosphorus concentration in shoot and root were evaluated. Results and Discussion: The results showed that Aspergillus niger and Aspergillus flavus had the highest (4.96) and the lowest (1.23) solubility index among the tested strains, respectively. The results from the laboratory experiment showed that phytase isolated from Aspergillus niger had the maximum amount of phytase activity (16.48 µmol/ min.ml) and phytase isolated from Aspergillus flavus had the minimum phytase activity (4.67 µmol/ min.ml). Aspergillus niger phytase was more effective compared to Aspergillus flavus and Aspergillus fumigatus phytases. The results of the greenhouse experiment represented that the highest amount of phosphorous in the shoot (0.125 percent), root (0.0102 percent), and shoot dry weight (46.08 g/pot) belonged to the maize plants treated by phytase isolated from Aspergillus niger in the presence of 50 mg/kg of sodium phytate. Generally, the results showed that Aspergillus niger strain was more effective than the other two strains in both laboratory and greenhouse experiments. Phytase enzymes isolated from strains had positive effects on phosphorous concentration in a different parts of maize plant and growth characteristics of maize. Phosphatase and phytase generally improve the availability of phosphorus from different phosphorus sources. It should be kept in mind that phytase also increases the bioavailability of other essential minerals such as Ca2+, Mg2+, P, Zn2+, Fe3+, which are bound to phytic acid. Since the phytase production by fungi has been attained by different cultivation methods (solid-state, semisolid, and submerged fermentation) it seems that different cultivation methods can affect the phytase efficiency. Therefore, we suggested that phytates from different cultivation methods can be tested for phosphorus bioavailability from different sources.
Hadiseh Rahmani; Amir Lakzian; Ali reza Karimi; Akram Halajnia
Abstract
Introduction: Laccases are potent enzymes that are capable of oxidizing various phenolic and non-phenolic compounds as well as resistant environmental pollutants. One of the most effective methods for improving their properties, such as increasing the stability of these enzymes and even increasing their ...
Read More
Introduction: Laccases are potent enzymes that are capable of oxidizing various phenolic and non-phenolic compounds as well as resistant environmental pollutants. One of the most effective methods for improving their properties, such as increasing the stability of these enzymes and even increasing their activity, is the immobilization of laccases on different carriers. In the process of immobilization, the enzyme is bonded to a solid carrier which is insoluble in the reaction mixture. In this process, the movement of the enzyme in space is severely restricted, while its catalytic activity is still maintained. One of the carriers used to create recyclable biocatalyst systems is mineral. Minerals as inorganic carriers are inexpensive, abundant in nature, readily available, and also have high biocompatibility. The objective of the present study was to investigate the adsorption properties of Laccase enzyme from T. versicolor fungus on montmorillonite K10 and zeolite minerals using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms.
Materials and Methods: For this study, the pure laccase enzyme (> 10U mg-1), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) substrate and montmorillonite K10 mineral (with a specific surface area of 220-270 m2/g and a cation exchange capacity (CEC) equal to 30 meq 100 g-1) were purchased from Sigma-Aldrich. Zeolite mineral was provided from a mine located in southeast Semnan province. Scanning electron microscopy (SEM) images of both minerals, CEC of zeolite with sodium acetate solution (pH=8.2) and zeolite surface area were determined. X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) analyzes of zeolite mineral were also done. In order to immobilize laccase on the minerals, 200 mg of both minerals were activated by shaking with 0.5N HNO3 for 2 hours and a solution of 2% 3-aminopropyltriethoxylane in acetone. The activated minerals were treated by a 5% solution of glutaraldehyde in a 0.1M sodium acetate buffer (pH=5) and were shaken for 24 hours with 0.25-2.0 mg of the laccase dissolved in the buffer. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms were determined. The experiment was carried out at a constant temperature of 20°C. The results were analyzed using the MSTATC software and the means of the data were compared using Duncan’s multiple range test.
Results and Discussion: Based on the results, the zeolite type was clinoptilolite with a chemical formula of (Na,K,Ca)2.5Al3(Al,Si)2Si13O36.12H2O. Moreover, BET Surface Area, Langmuir Surface Area, t-Plot Micropore Area and t-Plot External Surface Area of zeolite were 40.2712, 645.4780, 3.5188 and 36.7524 m2/g, respectively. Laccase absorption on montmorillonite K10 showed the highest compliance first with the Dubinin–Radushkevich model (R2=0.97) and then with the Langmuir adsorption isotherm model (R2=0.96). Based on the D-R model, the theoretical monolayer sorption capacity (qm) and the constant of the sorption energy (ß) of montmorillonite K10 were 3 mg/g and 0.62 (×103 mol2/J2), respectively. According to the Langmuir isotherm, there was probably a homogeneous distribution of active sites on the montmorillonite K10 mineral surface. On the other hand, laccase adsorption on zeolite showed the best compliance with the Freundlich model (R2=0.87). Accordingly, sorption capacity (KF) of zeolite was 0.05 mg/g (L/mg)1/n. The amount of n parameter as an indicator of the favorability of sorption process was 1.49 demonstrating favorable absorption condition. The values of R2 obtained for Temkin isotherm model were, however, equal in both minerals (R2=0.62 for montmorillonite K10 and R2 = 0.61 for zeolite), and based on this model, the adsorption process was likely to be exothermic. According to the values of the equilibrium parameter (RL) of montmorillonite K10, the absorption was favorable. However, with increasing the initial concentration of laccase, the amount of RL approached zero indicating the laccase adsorption on the mineral is more favorable at higher initial concentrations of laccase. Based on % Removal parameter, the highest percentage of laccase adsorption on montmorillonite K10 and zeolite was related to concentrations of 250 and 125 mg/L, respectively, which showed a statistically significant difference with other concentrations.
Conclusion: In general, laccase absorption on montmorillonite K10 showed the best fit with Dubinin–Radushkevich and Langmuir adsorption isotherm models. On the other hand, adsorption of laccase on zeolite mineral showed the best fit with Freundlich model. A higher degree of steric hindrance and conformational changes in the enzyme structure is likely to occur and subsequently, the catalytic efficiency of the enzyme complexes may decrease. Therefore, montmorillonite is more suited to be used as a carrier of laccase enzymes. However, complementary studies such as kinetic tests will help to make final decisions.
Mahdiyeh Momen; Ali reza Karimi; Akram Halajnia; Parisa Mirhoseini Moosavi
Abstract
Introduction: Sepiolite is a fibrous clay mineral which is usually found in Tertiary sediments in arid environments. The most abundance of sepiolite is between 30⁰ to 40⁰ latitudes of both northern and southern hemispheres. Sepiolite is an Mg-rich clay minerals which is very sensitive to weathering. ...
Read More
Introduction: Sepiolite is a fibrous clay mineral which is usually found in Tertiary sediments in arid environments. The most abundance of sepiolite is between 30⁰ to 40⁰ latitudes of both northern and southern hemispheres. Sepiolite is an Mg-rich clay minerals which is very sensitive to weathering. Sepiolite is an industrial mineral with a variety of applications due to its structural and chemical properties. However, the clay (e.g. palygorskite and smectite) and no-clay (e.g. dolomite and quartz) impurities reduce the quality of sepiolite. Therefore, removing the impurities enhances the quality of the main clay mineral. Mineral purification consists of a series of chemical (e.g. acid treatment) and physical (e.g. particle size fractionation, sieving, ultrasonic treatment) procedures. There is a sepiolite mine in the northeastern Iran, near the city of Fariman. The sepiolite is a sensitive clay to weathering, especially in acidic solution. Therefore, the objective of this study was to propose a simple physical method based on particle size fractionation to purify the sepiolite.
Material and Methods: Sepiolite mine is located around Elyator, a village near the city of Fariman. The relatively hard sepiolite samples were grinded and passed through a 2 mm sieve. To determine the mineralogical composition, the powdered samples were analyzed by X-ray diffractometer (model: Explorer). XRF spectroscopy (model: PHILIPS-PW148) was used to identify the elemental composition. Pipette method was used to separate the particle size fractions. Firstly, the samples were passed through a 270 mesh (50 µm) sieve. The 0-50 µm fraction was then transferred to the cylinder containing dispersion solution (0.1% sodium carbonate and sodium hexametaphosphate solution). Based on the settling time of the particles in the suspension, three classes of particle size of 20-50, 0-20 and 50 µm size (sand size) were about 20 % and those with less than 2 µm size (clay size) consisted 37 % of the sample. Silt size particles (2-50 µm) were about 43 % of the sample. The XRD diffractograms indicated that particle size fractionation considerably decreased the amount of quartz. Dolomite peaks were completely absent in the diffractogram of the < 2 µm fraction. Furthermore, the peaks of palygorskite were not present in diffractogram of 20-50 µm. The intensity of sepiolite peaks considerably increased and the intensities of the other minerals decreased in relation to bulk samples. This confirmed that the most impurities were in the fraction > 50 µm. The ratios of the sepiolite indicator peak to the dolomite, palygorskite and quartz indicator peaks in bulk sample were 5.11, 7.28 and 2.82. This ratio was very high for dolomite in < 2 µm fraction and for palygorskite in 20-50 µm fraction. A purification procedure should be both efficient and economic. The 0-20 µm fraction composed about 70 % the particles. The separation time for this fraction is also pretty fast. Therefore, 0-20 µm particles seem to be economically purified. Based on the conventional measurement method for carbonates (HCl digestion and NaOH titration method), the calcium carbonate equivalent in < 2 µm fraction was calculated to be about 10 % despite removal of dolomite in this fraction. This illustrates that HCl dissolved the sepiolite. However, if removal of dolomite from coarser fraction by HCl is needed, it should be applied in the solution with high amount of Mg to prevent sepiolite dissolution.
Conclusion: Dolomite, palygorskite and quartz were the impurities in Fariman sepiolite. There is no chemical treatment to remove the quartz and palygorskite. Dolomite can be easily removed using HCl, but it dissociates the sepiolite, too. The result indicated that particle size fractionation as a simple physical method purifies sepiolite effectively.
Hadis Hatami; Amir Fotovat; Akram Halajnia
Abstract
Introduction: After nitrogen, phosphorus is the second most frequently limiting macronutrient for plant growth. It participates in metabolic processes such as photosynthesis, energy transfer and synthesis and breakdown of carbohydrates. H2PO4- and HPO42- are two forms of this element which are present ...
Read More
Introduction: After nitrogen, phosphorus is the second most frequently limiting macronutrient for plant growth. It participates in metabolic processes such as photosynthesis, energy transfer and synthesis and breakdown of carbohydrates. H2PO4- and HPO42- are two forms of this element which are present in the soil solution in the available form. Due to phosphorus reactions with soil components (oxy or hydroxides of Fe and Al in acidic soils and Ca2+ and Mg2+ ions in calcareous soils), the availability of this element is a limiting factor for production of agricultural crops in the whole world. To minimize this problem it is needed to improve the recycling of phosphorus and develop new technologies to reduce phosphorus losses and increase its effectiveness. In the recent decades, layered double hydroxides (LDH) have been extremely used as an effective sorbent for organic and inorganic anions sush as phosphate. Furthermore, some studies have suggested that the phosphate form LDH is applicable as a slow release phosphate fertilizer. Therefore, the objective of the present study was to compare the effect of using Zn-Al LDH and triple superphosphate (TSP) as fertilizers on the availability of phosphorus over time in a calcareous soil.
Materials and Methods: At the first, nitrate containing Zn-Al LDH (N-LDH) was synthesized by urea hydrolysis method and then ion exchange method was used for the phosphate anions intercalation into N-LDH. In this process, 5.0 g of the N-LDH was suspended in 1000 mL of a solution 0.05 mol/L of K2HPO4. The suspension was kept for 12 h at room temperature (25 °C) under stirring. Afterwards, the material was filtered, washed with distilled water and dried at 70 °C for 18 h. The LDH sample produced by the ion exchange method was nominated as P-LDH. To compare the effects of P-LDH and TSP application on the availability of soil phosphorus, an incubation experiment was carried out using a completely randomized factorial design with two sources of phosphorus (P-LDH and TSP), four levels of phosphorus (0 (control), 18, 45 and 90 mg P kg-1), eight levels of time (1, 5, 10, 20, 40, 70, 100 and 150 days) and three replications. Available phosphorus and zinc, pH and EC of samples were measured at the end of each time period. Available phosphorus was extracted with 0.5 M sodium bicarbonate and phosphorus concentration was determined using the ascorbic acid method. Available zinc content was determined by atomic absorption spectrometry following extraction of the sample by DTPA-TEA method. Also, pH and EC were measured in water (soil/water ratio 1:2). Data analysis was performed by MSTAT-C software, and the means were compared at α꞊5% by Duncan test.
Results and Discussion: The results showed that the use of P-LDH and TSP significantly improved available phosphorus compared to control treatment. However, in contrast to TSP, available phosphorus in P-LDH treatments increased with increasing of time, up to significant difference which was observed between the two sources after 150 days. This result is probably due to slow release of phosphorus from P-LDH and reduction of phosphorus reactions with different soil components. Moreover, available zinc was higher for P-LDH treatments than TSP treatments as dissolution of P-LDH may concurrently release zinc ions into the soil solution. It seems that the application of P-LDH not only increased the availability of phosphorus but also improved available zinc. Therefore, due to the zinc deficiency in calcareous soils, P-LDH can be used as a suitable dual purpose fertilizer for these soils. However, the possibility of Zn toxicity risk due to higher level of LDH application in soil is not ruled out. It is worth mentioning that the variation of pH and EC values in P-LDH treatments showed no significant difference compared to TSP tratments. In other words, application of P-LDH increased soil available phosphorus and zinc without any negative effect on soil pH and EC.
Conclusions: The results of this study illustrated that the P-LDH probably can be used as a slow release phosphate fertilizer to increase the phosphorus efficiency; however, care should be taken as the high levels of this fertilizer may not be recommended due to the high zinc content. It should be noted that the high levels of phosphorus are not appropriate for all phosphorus fertilizers but in the present study we used the different levels of fertilizers because the behavior of P-LDH was not clear for us.
seyed sajjad hosseini; Amir Lakzian; Akram Halajnia
Abstract
Introduction: Application of EDTA may increase the heavy metal availability and phytoextraction efficiency in contaminated soils. In spite of that, it might also have some adverse effects on soil biological properties. Metals as freeions are considered to be severely toxic, whereas the complexed form ...
Read More
Introduction: Application of EDTA may increase the heavy metal availability and phytoextraction efficiency in contaminated soils. In spite of that, it might also have some adverse effects on soil biological properties. Metals as freeions are considered to be severely toxic, whereas the complexed form of these metalswith organic compounds or Fe/Mn oxides may be less available to soil microbes. However, apart from this fact, some of these compounds like EDTA and EDTA-metal complexes have low bio- chemo- and photo-degradablity and high solubility in their own characteristics andable to cause toxicity in soil environment. So more attentions have been paid to use of low molecular weight organic acids (LMWOAs) such as Citric acid because of having less unfavorable effects to the environment. Citric acid increases heavy metals solubility in soils and it also improves soil microbial activity indirectly. Soil enzymes activity is a good indicator of soil quality, and it is more suitable for monitoring the soil quality compared to physical or chemical indicators. The aims of this research were to evaluate the changes of dehydrogenase, urease and alkaline phosphomonoesterase activities, substrate-induced respiration (SIR) and Pb availability after EDTA and citric acid addition into a contaminated soil with PbCl2.
Materials and Methods: An experiment was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition. The soil samples collected from surface horizon (0-20 cm) of the Typic haplocalsids, located in Mashhad, Iran. Soil samples were artificially contaminated with PbCl2 (500 mg Pb per kg of soil) and incubated for one months in 70 % of water holding capacity at room temperature. The experimental treatments included control, 3 and 5 mmol EDTA (EDTA3 and EDTA5) and Citric acid (CA3 and CA5) per kg of soil. Soil enzymes activity, substrate-induced respiration and Pb availability of soil samples were determined by standard methods after 7, 14, 21 and 28 days of chelates addition.
Results and Discussion: The soil texture was loam and the indigenous Pb content was 25.55 mg kg-1. The soil pH was 7.4 and electrical conductivity of saturated extraction measured 2.5 dS m-1. The soil carbonate calcium was 14% and the content of organic carbon and essential nutrients were low. The results showed that EDTA3 and EDTA5 treatments increased Pb availability by 2.17% and 10% compared to control treatment but CA3 and CA5 treatments decreased it by 3.8% and 15.7% respectively. The Pb availability in control and EDTA5 treatments did not change during the incubation time. The available Pb concentration dropped sharply during the incubation time in EDTA3, CA3 and CA5 treatments. The reduction rates in CA3 and CA5 treatments were more than EDTA3 treatment. This may be due to the high stability and low biodegradability of EDTA than biodegradable chelators and low molecular weight organic acids. The results showed that urease and dehydrogenase activities were significantly reduced in EDTA3 and EDTA5 treatments compared to control treatment. Urease and dehydrogenase activities were decreased with the increase of EDTA concentration. Alkaline phosphomonoesterase activity was not affected by the EDTA3 and EDTA5 treatments. In CA3 and CA5 treatments, dehydrogenase and alkaline phosphomonoesterase activities significantly increased with increasing the concentration of citric acid. CA5 treatment showed a prominent effect on urease activity compare to CA3 treatment. The soil enzyme activities increased with incubation time. It seems that reduction in Pb availability causes an increase of soil enzymes activities. Significant negative relationships were found between soil enzymes activities and available Pb concentration (dehydrogenase activity (r=-0.906, P
salimeh rahemi; R. Khorassani; A. Halajnia
Abstract
With due attention to the low availability of iron in calcareous soils and different ability of plant species in iron acquisition, the study and identification of iron-efficient plants is necessary to reduce the use of chemical fertilizers. In this way, a greenhouse experiment was conducted to study ...
Read More
With due attention to the low availability of iron in calcareous soils and different ability of plant species in iron acquisition, the study and identification of iron-efficient plants is necessary to reduce the use of chemical fertilizers. In this way, a greenhouse experiment was conducted to study of iron uptake efficiency in different wheat varieties, as a randomized complete blocks design with factorial arrangement. Treatments consisted of three levels of Fe (0, 2 and 6 mg kg-1) and three varieties of wheat (Falat ٫Parsi ٫Pishtaz) with three replications. The results showed that iron application had no effect on shoot dry weight and iron uptake in Parsi and Pishtaz varieties, but increased those in the Falat variety. The study of influx and root-shoot ratio, which are two important factors in the iron uptake by plant, showed that the Parsi and Pishtaz varieties had higher influx than the Falat variety. In the Parsi variety as well as influx, the root length had an important role in iron uptake efficiency. In the Falat variety with increasing amounts of iron uptake, relative shoot dry weight, influx and root-shoot ratio were increased. Therefore, the Falat variety in comparison to two other varieties was not an iron efficient plant. Lack of response to Fe fertilizer in the Pishtaz and Parsi varieties indicated some other specific uptake mechanisms were involved at low Fe levels in soil. Finally, the results showed that the Pishtaz and Parsi varieties were more efficient in iron uptake than Falat variety.
A. Lakzian; A. Halajnia; H. Rahmani
Abstract
Abstract
Soil drying and rewetting (DRW) cycles are considered as environmental stress that would affect the physical, chemical and biological properties of soil and nutrient cycles. The study of soil drying and rewetting effects on plant nutrition and soil fertility is very important and crucial specially ...
Read More
Abstract
Soil drying and rewetting (DRW) cycles are considered as environmental stress that would affect the physical, chemical and biological properties of soil and nutrient cycles. The study of soil drying and rewetting effects on plant nutrition and soil fertility is very important and crucial specially their environmental effects. In this study, the effects of 1, 2, 3, 4 and 5 drying and rewetting cycles on dissolved organic carbon (DOC) and phosphorus (DOP) and available forms of nitrogen (nitrite, nitrate and ammonium) in two Alfisols in a completely randomized design with three replications were investigated. The results showed that with increasing DRW cycles dissolved organic carbon, organic and inorganic phosphorus and ammonium decreased significantly in soil solution compared to control (samples were kept in wet condition). Reduction in DOC and DOP could be due to the higher mineralization of organic carbon and phosphorus. Dissolved organic nitrogen decreased significantly after three and four drying and rewetting cycles in soil 1 and soil 2 respectively. The highest amount of dissolved organic nitrogen was obtained in five drying and wetting cycles treatment.
Keywords: ِDrying and rewetting, Dissolved organic carbon, Phosphorus and nitrogen
M. Mossadeghi; A. Lakziyan; Gh. Haghnia; A. Fotovat; A. Halajnia
Abstract
Dissolved Organic nitrogen (DON) is an important constituent of Dissolved Organic Matter (DOM). It has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. Dissolved inorganic nitrogen, which is another form of ...
Read More
Dissolved Organic nitrogen (DON) is an important constituent of Dissolved Organic Matter (DOM). It has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. Dissolved inorganic nitrogen, which is another form of total soil dissolved nitrogen, includes NO3, NO2 and NH4, which is very important for plant nutrient. Soil managements such as fertilizer application affects the flux and concentration of DON and DIN in soils. The purpose of this study was to evaluate the effects of different N-fertilizers application on DON and DIN content of two Alfisols located in near the Caspian Sea in the north of Iran. An experiment carried out using complete randomized design with factorial arrangements. Four level of N-fertilizers (Urea, Ammonium nitrate, Ammonium sulfate with Control)) and six different times (0, 7, 14, 28, 42, 60 day) with three replications in two different soils. Changes in DON, DIN, pH and soil respiration were monitored during the period of 60 days. The results showed that dissolved organic nitrogen decreased significantly by N- fertilizer application in both soil samples however, NO3, NO2 and NH4 increased. Ammonium sulfate showed the maximum effect on DON reduction and it can be due to the pH reduction. Changes in DON during the experiment varied from 11 to 75 % in both soil. At the end of experiment, NO3 + NO2 formed a major part of total Dissolved nitrogen in soils.
A. Halajnia; Gh. Haghnia; A. Lakziyan; A. Ramezanian
Abstract
Elevated atmospheric carbon dioxide and other green house gases have increased the Earth temperature in recent century, which it affects all biochemistry cycles in soils. To examine the effect of atmospheric CO2 concentration and temperature on N forms in soil solution in a calcareous soil, an experiment ...
Read More
Elevated atmospheric carbon dioxide and other green house gases have increased the Earth temperature in recent century, which it affects all biochemistry cycles in soils. To examine the effect of atmospheric CO2 concentration and temperature on N forms in soil solution in a calcareous soil, an experiment was conducted in a completely randomized design with factorial arrangement in the laboratory conditions. Initially, soil was treated with one percentage of cattle manure compost and 200 kg ha-1 of urea, then changes in forms of soil nitrogen (total dissolved nitrogen, dissolved inorganic nitrogen, dissolved organic nitrogen, sum of nitrate and nitrite and ammonium) were evaluated in two levels of temperature (25 and 35 oC) and two different carbon dioxide concentrations (350 and 700 ppm) during 60 days of incubation with three replications. The results showed that the effect of carbon dioxide on nitrogen forms was different at 25 and 35 oC. Carbon dioxide increased dissolved organic nitrogen but dissolved inorganic nitrogen and nitrate and nitrite decreased at 25oC treatment. While total dissolved nitrogen, dissolved inorganic nitrogen and NO2 + NO3 increased at 750 ppm of carbon dioxide treatment, it had no effect on dissolved organic nitrogen. Changes in dissolved organic nitrogen were higher than other forms of nitrogen during the experiment. The maximum and minimum dissolved organic nitrogen were occurred faster than other nitrogen forms at 35 oC treatment. The results of this experiment showed that elevated carbon dioxide with increasing temperature increased the rate of nitrogen biochemical reactions in soil.
A. Lakziyan; A. Halajnia; M. Nasiri Mahalati; F. Nikbin
Abstract
Abstract
Arsenic (As) contamination of soils is a global problem. Legumes are often used in remediation of contaminated sites because of their capacity to fix nitrogen. In the present study, the effects of inoculation of bean (by Rhizobium leguminosarum bv. phaseoli) on plant uptake and tolerance to ...
Read More
Abstract
Arsenic (As) contamination of soils is a global problem. Legumes are often used in remediation of contaminated sites because of their capacity to fix nitrogen. In the present study, the effects of inoculation of bean (by Rhizobium leguminosarum bv. phaseoli) on plant uptake and tolerance to arsenic were investigated. An experiment with a factorial arrangement, two levels of inoculation (with and without inoculation) and five levels of arsenic concentrations (0, 2.5, 5, 7.5 and 10 μM) in completely randomized design with three replications was carried out in a sand culture system in a green house condition. The results showed that the dried shoot weight was increased significantly by inoculation treatments. However, dried root weight and plant height were not affected by inoculation. Dried shoot weight was significantly decreased by increasing arsenic concentrations. The least dried shoot weight was observed in 5, 7.5 and 10 μM of arsenic. The response of dry root weight and plant height to arsenic concentrations was similar to dried shoot weight. The least nodule number was observed in 5 μM arsenic treatment and nodule number in other treatments was not affected by arsenic concentration. Arsenic concentration in shoot increased by Rhizobium leguminosarum bv. phaseoli inoculation. The concentration of arsenic in bean shoot increased by increasing arsenic concentrations in medium. However the highest concentration of arsenic in root and the least nodule number were observed in 5 μM arsenic.
Key words: Arsenic, Sand culture, Nodulation Inoculation
A. Lakziyan; A. Halajnia; Gh. Haghnia; A. Ramezanian
Abstract
Abstract
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. ...
Read More
Abstract
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.
Key words: Zinc, Copper, Cadmium, Corn, Sunflower
H.R. Mohammadpouran; A. Fotovat; Gh. Haghnia; A. Halajnia; M. Chomsaz
Abstract
Abstract
Chromium is among the metals that has numerous applications in various industries due to its specifications. Widespread use of this metal in different industries has unfortunately been accompanied by its increased release into environment and this entails numerous environmental hazards. In ...
Read More
Abstract
Chromium is among the metals that has numerous applications in various industries due to its specifications. Widespread use of this metal in different industries has unfortunately been accompanied by its increased release into environment and this entails numerous environmental hazards. In the first phase of the research that was conducted to evaluate the effect of the leather processing companies' sewage on chromium behavior on soil, samples of soil affected by the sewage of leather processing companies were studied Hexavalent chromium and chromium distribution ratio in exchangeable organic, carbonated and residual fractions of these soils were examined. The second phase of this research was conducted to assess the effect of time, chromium, soil texture and soil organic mater on chromium distribution in soil fractions. In this phase of the research also the reduction process of hexavalent chromium with time was evaluated. In the evaluation of the soils affected with chromium in Charmshahr area of Mashhad the contamination was observed in 45-centimeter depth of the soil. In sequential extractions of these soils it was shown that 90% of the chromium was in the residual fraction. The chromium distribution order in various fractions of these soils was as follows:
Exchange fraction> Organic fraction> Carbonated fraction> residual fraction
The results showed that time had an important effect on the chromium distribution in various soil fractions especially in short term. Treatments of this section had not a significant effect on the chromium distribution in various fractions statistically except in limited cases. Among the most important results of this phase, we can cite the increased contribution (percentage) of chromium to exchangeable fraction with increased level of chromium in soil and this is so important from the environmental point of view.
Key word: Chromium, Organic matter, Fraction
A. Halajnia; A. Lakziyan; Gh. Haghnia; A. Ramezanian
Abstract
Abstract
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 ...
Read More
Abstract
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.
Key words: Cadmium, Corn, Sunflower, Iron, Manganese
