Soil science
Mahvan Hasanzadeh Bashtian; Alireza Karimi; Adel Sepehr; Amir Lakziyan; Omid Bayat
Abstract
Introduction
Soils and landforms have a strong relationship and archive evidence of climatic and environmental changes. Alluvial fans are one of the most important landforms in arid and semi-arid regions of Iran. Climate changes in the Quaternary, especially in the late Pleistocene, had a significant ...
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Introduction
Soils and landforms have a strong relationship and archive evidence of climatic and environmental changes. Alluvial fans are one of the most important landforms in arid and semi-arid regions of Iran. Climate changes in the Quaternary, especially in the late Pleistocene, had a significant effect on the evolutions of alluvial fans in arid and semi-arid regions. Alternate of sedimentation and soil formation in alluvial are the consequences of periodic climate change. Organisms are one of the main factors of soil formation. Biological crusts are part of organisms that are abundant in dry lands and especially in alluvial fans; however, their role in soil formation has been less studied. Biological soil crusts by providing the suitable biological activity, effect on trapping of aeoilian materials and hydrological processes affect the soil formation processes. The chemical properties of the soil affect the catabolic capacity of the soil and it is very different among the different layers of the soil. However, few studies have addressed the effect of processes on soil microbial respiration during change and evolution and pedogenic state. The objectives of this research were to 1) investigate the evolution of soils along the gradient from upstream to downstream of the alluvial fan and 2) investigate the changes in microbial respiration in different layers of soil and the factors affecting it.
Materials and Methods
The studied area is an alluvial fan in Razavi Khorasan province, in the southern slopes of the Binaloud mountain range. The climate of the region is semi-arid and the soil moisture and temperature regimes are Aridic border on Xeric and mesic, respectively. Three soil profile in the upper, middle, and base part of the alluvial fan were described. Bulk and undisturbed soil samples were collected from various soil horizons for subsequent physical, chemical, and micromorphological analyses. In addition, the microbial soil respiration was measured in all horizons. The soils were classified according to Soil Taxonomy and World Reference Base methods.
Results and Discussion
Sequences of sedimentation and soil formation were observed in the soil profiles. Vesicular (V), argillic (Bt), argillic-calcic (Btk), calcic (BCk) and cambic (Bw) horizons were the diagnostic soil horizons of the studied soils. Soil profiles of the middle and base were Xeric Calciargids in the subgroup category of Soil Taxonomy; while soil profile of the apex soil was Xeric Haplocambids. In the profiles, a thin vesicular horizon (V) was formed under the desert pavement. Below the vesicular horizon, evidence of clay illuviation, pedogenic carbonate nodules, and calcium oxalates in roots were observed in thin sections. This evidence shows the role of biological crusts in the formation of these features. In the lower horizons of the profiles, pedogenic carbonate nodules, carbonates pendants and clay coatings were observed. It seems that the upper soil (vesicular and underlying Bt horizons) were developed in the more humid periods of the Holocene, and biological crusts also played a key role in the processes of calcification and clay illuviation. The argillic horizons in the lower layers were formed during the stable periods of the late Pleistocene. The irregular microbial respiration mainly indicated difference in microbial activities labile organic matter content. The argillic horizons had the lowest microbial respiration, due to decomposition of organic materials during soil formation. In contrast, soil respiration was the highest in surface and calcic horizons. It seems that preservation of organic materials by carbonate complication. However, it is suggested to investigate the carbon fractions in relation to microbial biomass in the studied horizons.
Conclusion
In this area, biological crusts and vegetation affected the formation of soil in the aeolian sediments of the Vk and AVk horizons and played a significant role in creating the Bt horizon in profiles 2 and 3. The study of landform profiles showed the formation of calcic and argillic horizons in the past climate, while the Bt horizon of the upper layers was formed in the current Holocene period. This form of the argillic horizon is slightly different from the soils of the Iranian region because these horizons have not been reported so far. It has been proven that there were humid periods in the Holocene, and it needs more studies at present. The study of soil microbial respiration in landform horizons showed that argillic horizons decreased the amount of microbial respiration, while it increased in classical horizons.
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 ...
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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 ...
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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 ...
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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
S. Balandeh; A. Lakzian; A. Javadmanesh
Abstract
Introduction: Silver nanoparticles (AgNPs) have a broad spectrum of uses, therefore, AgNPs will be released from those products into many different ecosystems. In the last decades, AgNPs have received substantial attention due to their distinctive physical and chemical properties such as high thermal ...
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Introduction: Silver nanoparticles (AgNPs) have a broad spectrum of uses, therefore, AgNPs will be released from those products into many different ecosystems. In the last decades, AgNPs have received substantial attention due to their distinctive physical and chemical properties such as high thermal and electrical conductivity, chemical stability, catalytic activity and antimicrobial properties against microbes such as bacteria, fungi, and viruses. There are many parameters for assessment effect of toxicity due to AgNPs but soil microbial community is one of which considered being an important target for assessing the impact of manufactured nano-materials on the terrestrial environment. Toxicity of AgNPs is due to the physical interaction of AgNPs with microorganisms and the production of reactive oxygen species (ROS). Although as we have been known harmful effects of AgNPs on the soil bacterial community, but the most information about antimicrobial properties of AgNPs come from the routine lab instructions such as soil respiration, substrate induced respiration and microbial biomass and colony forming unite. So, the objective of this paper was to study the effects of silver nanoparticles on microbial activity using the routine lab instructions and compare with the obtained data from the molecular genetic techniques. In this paper, the quantitate population of soil bacterial was estimated using Real time qPCR with the MIQE guidelines. Materials and Methods: In order to study the effect of silver nanoparticles on microbial activity and bacterial population in a calcareous soil, an experiment was conducted as a completely randomized design based on factorial arrangement with three replications. Experimental factors included silver slat forms (AgNPs and AgNO3), Ag concentrations (0, 0.5, 5, 10, 50, and 100 mg Ag kg-1 dry soil) and incubation time (7 and 42 days). Soil samples (Typic Haplicambids) with clay loam texture and seven percent of calcium carbonate was collected from Research Field of Ferdowsi University of Mashhad, Mashhad, Khorasan Razavi, Iran. The soil samples were amended with different concentrations of AgNPs and incubated at 25oC for 42 days. The water content of soil samples was adjusted at 70% WHC during the incubation time. After 7 and 42 days of incubation, the soil substrate-induced respiration (SIR), heterotrophic plate count (HPC), and soil urease and dehydrogenase activities were measured. Finally, based on the obtained data, the soil biological quality index was estimated using the soil biological parameters. In order to quantify the total bacterial population, DNA was extracted from soil samples and was estimated using the relative concentration of 16S rDNA gene by a quantitative Polymerase Chain Reaction (qPCR), with a minimum information for publication of quantitative real-time PCR experiments (MIQE) guidelines. Results and Discussion: The results showed that with increasing the concentration of both AgNPs and AgNO3, the activity of dehydrogenase and urease in soil samples decreased during the incubation times. Microbial substrate induced respiration (SIR) and the total bacterial population in soil samples considerably declined at the end of experiment. Bacterial population in AgNPs treatments decreased compared to AgNO3 treatments but the reduction was not statistically significant. Over time, soil dehydrogenase activity and soil SIR decreased in both AgNPs and AgNO3 treatments, while soil urease activity and heterotrophic bacterial populations improved but again in heterotrophic bacterial populations was not statistically significant. The soil biological quality index was estimated from the soil biological data. AgNO3 treatments reduced the soil biological quality index compared to AgNPs treatments. In other words, the results showed that AgNO3 was more toxic to soil bacteria activity compared to AgNPs. The lowest soil urease and dehydrogenase enzyme activity and soil biological quality index were observed in the treatment of 100 mg kg-1 dry soil AgNO3 after 7 days of incubation. The application of 0.5, 5, 10, 50, and 100 mg Ag kg-1 dry soil decreased relative soil bacterial population by 22%, 40%, 59%, 73%, and 82% in AgNO3 treatment and 10%, 30%, 68%, 76%, and 86% in AgNO3 treatment compared to control after 42 days of incubation, respectively. Conclusion: The results of this study showed that silver nanoparticles can negatively affect the enzymes involved in the nitrogen and carbon cycle. The AgNPs had less toxicity effect on the soil microbial activity compared to AgNO3. However, AgNPs was more toxic to soil bacteria populations compared to AgNO3. Different behavior AgNPs and AgNO3 in calcareous soil needs more investigations but there is no doubt that AgNPs is as an emerging contaminant and it has high toxicity potential for soil microbial community.
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 ...
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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.
atena mirbolook; Mirhasan Rasouli-Sadaghiani; E. Sepehr; A. Lakzian; M. Hakimi
Abstract
Introduction: Iron (Fe) is an important micronutrient that plays a role in several crop physiological processes such as photosynthesis, respiration, and synthesis of heme proteins, DNA, RNA, and hormones. The most common Fe source used in agriculture is Fe-EDDHA. However, the usage of this chelate may ...
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Introduction: Iron (Fe) is an important micronutrient that plays a role in several crop physiological processes such as photosynthesis, respiration, and synthesis of heme proteins, DNA, RNA, and hormones. The most common Fe source used in agriculture is Fe-EDDHA. However, the usage of this chelate may be problematic for plant growth. In the recent years, organic chelates have gained attention as they increase the microelements solubility and prevent iron precipitation in nutrient solution. Organic chelates such as amino acids and polysaccharides have many physicochemical (reactive OH, COOH and NH2 groups) and biological (biocompatible and biodegradable) properties that make these attractive materials usable for the agricultural practice. Biodegradability, low toxicity, immune system stimulation, the ability to coordinate metal, less sensitivity to photodegradation, and the effect on physical properties of rhizosphere and root growth dynamic are ideal properties of these components. The objective of this study was to evaluate Fe-organic-chelates efficiency as Fe sources for bean (Strategy I) and corn (Strategy II) growth in the hydroponic system. Materials and Methods: In this research, we synthesized Fe-amino acid chelates including Fe-Glycine (Fe-Gly), Fe-Phenylalanine (Fe-Phe), Fe-Tyrosine (Fe-Tyr), Fe-Methionine (Fe-Met), and Fe chitosan chelates in two forms of acidic hydrolyzed chitosan [Fe-C(A.hyd)] and enzymatic hydrolyzed chitosan [Fe-C(E.hyd)] and characterized by FTIR and CHN analyzer. The efficiency of these iron sources for bean (Strategy II) and corn (Strategy I) in hydroponic system was then evaluated. Seeds of bean and corn were washed with distilled water and transplanted into special containers containing coco peat, perlite and vermicompost (1:1:1) at 25 °C for germination and initial growth. The seedlings were transferred to polyethylene plastic lids fitting tightly over 8-L polyethylene containers under controlled conditions in the greenhouse with a light period of 8 hours per day, the temperature of 20 to 25°C and relative humidity of 65 to 75%. The pots were stacked in black color to prevent light reaching the root of the plant and the solution. In each pot, one plant seedling was placed and the basic nutrient solution was prepared in deionized water. The plants were harvested after 8 weeks, their root and shoot were separated and dried after washing with distilled water in an oven at 75 ° C. The dried samples were ground to fine powder to pass through a 20-mesh sieve. The analysis of Fe in samples was performed using atomic absorption spectrophotometer. Result and Discussion: Application of organic chelates of amino acids and chitosan increased the shoot dry matter per plant compared to Fe-EDDHA. Fe content in shoot of corn and bean was highest using Fe-Tyr, Fe-Met and [Fe-C(A.hyd)]. Uptake and accumulation of Fe in roots were observed by using all chelates, but the highest translocation factor was found for the treatments including [Fe-C(A.hyd)] and Fe-Tyr. Translocation factor in bean plants was higher than corn, and around half of Fe in bean plants was translocated from root to shoot. The use of iron chelates in plant growth medium increased the activity of ferric chelates reductase enzymes in bean and corn compared to Fe-EDDHA. However, the mean of this enzyme activity in bean was higher than that in corn. Therefore, the activity of this enzyme can be used as an indicator for determining the iron availability in leaf cells in Strategy I and Strategy II plants. In general, the plants need less energy to absorb Fe when the chelates with a simpler structure are used. Conclusion: The results indicated that using Fe organic chelates in the hydroponic system could supply sufficient amounts of iron for the plant uptake and also improve the root and the shoot growth of bean and corn. Overall, the effect of Fe organic chelates on Fe content of bean and corn shoots was in the following order: Fe- Chi(A.hyd) > Fe-Tyr > Fe-Met > Fe-Gly >. Activity of leaf ferric chelate reductase in bean was higher than that in corn.
S. Sangsefidi; A. Lakzian; A.R. Astaraei; M. Banayan; M. Mazhari
Abstract
Introduction: Nitrification inhibitors are compounds that slow biological oxidation of ammonium to nitrite by reducing the activity of Nitrosomonas bacteria, without affecting the subsequent oxidation of nitrite to nitrate, either by inhibiting or interfering with the metabolism of nitrifying bacteria. ...
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Introduction: Nitrification inhibitors are compounds that slow biological oxidation of ammonium to nitrite by reducing the activity of Nitrosomonas bacteria, without affecting the subsequent oxidation of nitrite to nitrate, either by inhibiting or interfering with the metabolism of nitrifying bacteria. The first step of nitrification is inhibited (i.e., the activity of Nitrosomonas bacteria) by the nitrification inhibitors, while the second step for oxidation of nitrite (NO2-) to nitrate (NO3-) is normally not influenced. In recent years, numerous compounds have been identified and used as nitrification inhibitors, particularly in agricultural soils. They are chemical compounds that slow the nitrification of ammonia, ammonium-containing, or urea-containing fertilizers, which are applied to soil as fertilizers, such as thiourea, carbon Sulfide, thioethers, ethylene, 3-amino-1,2,4-triazole, dicyandiamide (DCD), 2-amino-4-chloro-6-methyl pyrimidine, ammonium thiosulphate and 3,4-dimethylpyrazole phosphate (DMPP). These inhibitors reduce the losses of nitrogen in soil. Some nitrification inhibitors are very effective in the efficiency of the nitrogen fertilizers. Recently, a lot of attention has been paid to nitrification inhibitors from an environmental point of view. Some nitrification inhibitors are very expensive and not economically suitable for land application. Nonetheless, many farmers and researchers apply these compounds for many purposes in some specific places. On the other hand, there are many inexpensive natural nitrification inhibitors such as Artemisia powder, Karanj (Pongamia glabra), neem (Azadrachta indica) and tea (Camellia sinensis) waste which can compete with the artificial nitrification inhibitors such as 3, 4-dimethylpyrazole phosphate (DMPP), dicyandiamide (DCD) which are very common nitrification inhibitors. Applying 1.5 kg ha-1 of DMPP is sufficient to achieve optimal nitrification inhibition. 4-dimethylpyrazole phosphate (DMPP) can significantly shrink nitrate (NO3) leaching. 4-dimethylpyrazole phosphate (DMPP) may also decrease N2O emission and the use of DMPP-containing fertilizers can improve yield. The aim of this study was to compare the effect of 3, 4-dimethylpyrazole phosphate (DMPP), Dicyandiamide (DCD) and powder Artemisia (ART) at the presence of Urea, cow manure and Vermicompost.Material and Methods: Effects of three nitrification inhibitors, (3, 4-dimethylpyrazole phosphate (DMPP), Dicyandiamide (DCD) and powder Artemisia (ART)) at the presence of three nitrogen sources (Urea, cow manure and Vermicompost) were investigated in a calcareous soil under lettuce cultivation in a greenhouse condition. The changes in the soil mineral nitrogen (nitrate and ammonium), plant nitrogen, nitrate accumulation in leaves and some of growth characteristics such as lettuce chlorophyll content, leaf area index, leaf dry weight and root dry weight were determined. The experiment was carried out in a completely randomized factorial design with three replications. Soil ammonium and nitrate concentration were measured during the experiment. The growth characteristics of lettuce were also measured at the end of experiment. Nitrogen and nitrate contents were also determined in lettuce leaves. Results and Discussion: The results of the experiment showed that soil nitrate decreased at the presence of three nitrification inhibitors but the soil nitrogen ammonium increased significantly. Application of nitrification inhibitors also reduced the concentration of nitrate in the lettuce leaves during two harvesting times. Moreover, the nitrogen concentration in the plant increased at the presence of nitrification inhibitors. The application of nitrification inhibitors influenced the plant growth characteristics and changed the lettuce growth characteristics. Chlorophyll content increased significantly in lettuce leaves. Leaf area index, leaf and root dry weight of lettuce increased notably when 3, 4-dimethylpyrazole phosphate (DMPP) and powder Artemisia (ART) nitrification inhibitors were applied to the soil samples. These growth characteristics, however, reduced significantly when dicyandiamide nitrification inhibitors was applied to the soil samples. In addition, the symptoms of toxicity were observed in lettuce plant when dicyandiamide nitrification inhibitors were applied to the soil samples. In general, the highest efficiency of nitrification inhibitors was recorded at the presence of urea fertilizer source and the greatest efficiency was observed initially for powder Artemisia (ART) and then for 3, 4-dimethylpyrazole phosphate (DMPP) and dicyandiamide, respectively, when urea fertilizer was applied to the soil samples. There was a positive correlation between soil nitrogen content and plant nitrate in the first and second harvest. The correlation between soil ammonium and plant nitrate (in the first and second harvest) and soil nitrate was negative.
S. Soleymani; A. Lakzian; A. Fottovat
Abstract
Introduction: Environmental contamination by crude oil and its various processing products is becoming a common phenomenon which severely damages soil and groundwater resources. Among the constituents of oil waste, polycyclic aromatic hydrocarbons (PAHs) are of environmental concern because of their ...
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Introduction: Environmental contamination by crude oil and its various processing products is becoming a common phenomenon which severely damages soil and groundwater resources. Among the constituents of oil waste, polycyclic aromatic hydrocarbons (PAHs) are of environmental concern because of their toxic, mutagenic and/or carcinogenic effects. Bioremediation involves the use of living microorganisms, bacteria or fungi, for detoxification of soil and water organic pollutants by biodegradation, biotransformation, and/or mineralization. Collaboration between different microbes under co-culture conditions such as co-metabolism or antagonism makes the system to perform better than a single microorganism. Total petroleum degradation is a result of a microbial consortium action, which is composed of different species with specific biochemical roles. On the other hand, the majority of components of petroleum products has low solubility in water and tends to bind to soil particles reducing their availability to microorganisms for degradation. This has been well described as a major limitation to the bioremediation of hydrocarbon contamination. The surfactants can be employed to enhance hydrocarbon biodegradation by mobilization, solubilization, or emulsification. Some microorganisms synthesize a wide range of surface-active compounds, generally called biosurfactants, which increases the bioavailability of these compounds. The application of these microbial surfactants in the remediation of hydrocarbons aims to increase their bioavailability or mobilize and remove the contaminants by pseudo-solubilization and emulsification in a treatment process. This work aimed to investigate the impact of the biosurfactant producing consortium on the benzo(a)pyrene biodegradation.
Materials and Methods: Four gasoline contaminated soils were enriched in Bushnell-Hass mineral medium with Benzo(a)pyrene (200 mg/l) for three months at 30°C. After this time, to obtain Benzo(a)pyrene-degrading isolates, 0.1 ml of soil suspensions were plated on BH agar plates containing pollutant. Three colonies with different morphological distinct properties were purified on LB agar plates. The screening of the most potent surfactant strain was assayed quantitatively using measurement of surface tension by the Du Nouy ring method. For increasing the production of biosurfactant, medium conditions including pH (6, 7, 8), temperature (25, 30, 35) and carbon source (glucose, sucrose and ribose) were optimized with fractional factorial based on Taguchi. The capability of the isolates and consortium in hydrocarbon biodegradation was investigated in liquid medium of Bushnell-Hass with 150 ppm of Benzo(a)pyrene, during 14 days. Treatments included inoculation of isolates AP3 and BM1 and their consortium in presence and absence of extracted isolates biosurfactants and control (no isolate and biosurfactant). Based on the results of Benzo(a)pyrene degradation in the liquid medium, AP3 isolate, consortium and biosurfactant extracted from AP3 were selected for soil experiment. Four sets of biodegradation experiments were carried out with soil contaminated by 150 ppm of benzo(a)pyrene for 45 days, as follows: set 1: soil + AP3 isolate; set 2: soil + consortium; set 3: soil + consortium + AP3 biosurfactant and set 4: blank (soil). The residual concentrations of contaminant were extracted on days 15, 30 and 45 by dichloromethane solvent and analyzed using GC-FID.
Results and Discussion: The results revealed that strains AP3 and BM1 showed a significant potential to produce surface-active agents in the presence of Benzo(a)pyrene as substrate, reducing the surface tension to 43 and 46 mN/m, respectively. Taguchi experimental design method was applied in order to optimize the biosurfactant production by isolates. Results of experiments indicated that the optimum biosurfactant production conditions were found to be temperature of 35º C and pH of 7, and glucose as water soluble carbon source. The produced biosurfactant reduced surface tension to 31/52 mN/m and 30/81 mN/m for BM1 and AP3, respectively. Biodegradation experiments of Benzo(a)pyrene in liquid cultures showed that the overall biodegradation efficiency of the individual isolates after 14 days was lower than consortium. Bacterial consortium enhanced degradation of contaminant to 87.3% (with addition of biosurfactant) compared to 27.6% of removal in presence of BM1 isolate. However, there was no statistically significant change in the degradation rates of contaminant in consortium with addition of AP3 and BM1 surfactant and surfactant free (87.3, 85.6 and 86.8%, respectively). The degradation of Benzo(a)pyrene was significantly enhanced in presence of AP3 biosurfactant at individual BM1 treatments (28.3 and 44.5 to 74.8%). Maximum degradation of Benzo(a)pyrene in contaminated soil was found (100%) in set 3: soil + consortium + AP3 biosurfactant. Based on GC-MS analyses, it degraded around 100% of penzo(a)pyrene, used as the sole carbon and energy source, at an initial concentration of 150 mg L-1, after 45 days of incubation, while alone consortium and isolate were able to remove 86% and 68% of hydrocarbon, respectively. Overall, these results provide evidence that consortium and AP3 biosurfactant could be potential candidates for further bioremediation.
Conclusion: The results revealed that the hydrocarbon removal efficiency of the consortium was higher than single species, and the final removal efficiency for the consortium could be reached in a considerably shorter time. The results suggest that biosurfactant-assisted bioremediation may be a promising practical bioremediation strategy for aged PAH-contaminated soils. It is evident from the results that the consortium alone and its producer species are both capable of promoting biodegradation to a large extent.
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 ...
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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.
Farsila Mahmoudian; Ali reza Karimi; Amir Lakzian
Abstract
1- Abdelkhalik Ibrahim M.A. 2011. Argillic horizons and clay-sized particles - an alternative interpretation of their dynamics in sola development and across catenas. Ph.D. Thesis, Iowa State University, 127p.
2- Bayat O., Karimzadeh H.R., Karimi A., Eghbal M.K., and Khademi H. 2013. Pedogeomorphic ...
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Setareh Sharifi; Amir Lakzian; Alireza Astaraei; nasrin ghorbanzadeh
Abstract
Introduction: Iron cycle is one of the most important biogeochemical processes which affect the availability of iron in soils. Ferric iron oxides are the most abundant forms of iron in soils and sediments. Ferric iron is highly insoluble at circumneutral pH. Present investigations have shown that the ...
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Introduction: Iron cycle is one of the most important biogeochemical processes which affect the availability of iron in soils. Ferric iron oxides are the most abundant forms of iron in soils and sediments. Ferric iron is highly insoluble at circumneutral pH. Present investigations have shown that the structural ferric iron bound in clay minerals is reduced by some microorganisms. Anaerobic bacteria reduce ferric iron which bound to soil clay minerals under anaerobic conditions. They have the ability to use ferric iron as a terminal electron acceptor. Many studies presented that dissimilatory iron reducing bacteria (DIRB) mediate the transfer of electrons from small organic molecules like acetate and glucose to various humic materials (electron shuttles) which then pass electrons abiotically to ferric iron oxyhydroxide and phyllosilicate minerals. Electron shuttles like AQDS, a tricyclic quinone, increase the rate of iron reduction by iron reducing bacteria on sites of iron oxides and oxyhydroxides. By increasing the rate of bioreduction of ferric iron, the solubility and availability of iron enhanced meaningfully. Royer et al. (2002) showed that bioreduction of hematite (common iron mineral in soils) increased more than three times in the presence of AQDS and Shewanella putrefaciens comparedto control treatments. Previous works have mostly used synthetic minerals as electron acceptor in bioreduction process. Furthermore, the effect of quinones as electron acceptor for microorganisms were studied with poorly crystalline ferric iron oxides . The main objective of this study was to study the effect of AQS, humic acid and fulvic acid (as electron shuttle) and Shewanella sp. and Pseudomonas aeruginosa, on bioreduction of native ferric iron in two acidic and calcareous soils.
Materials and Methods: An experiment was conducted in a completely randomized design with factorial arrangement and three replications in vitro condition. The soil samples collected from locations in Mashhad and Guilan cities, Iran, in 2015. The soil samples were air dried in a glasshouse and later subjected to general analysis. Some part of the soil samples were kept at 4 oC as fresh soil samples for bioreduction assay. In that part of experiment, all soil samples were treated with glucose (10 mM) as electron donor. Native ferric iron considered as electron acceptor. Then soil samples were treated with AQS, humic acid and fulvic acid (as electron shuttles) and inoculated with bacterial cells (Shewanella sp. and P. aeruginosa) and they were incubated for 30 days in an incubator at 30 and 37 oC according to the optimum temperature for bacteria in an anaerobic condition. At the end of incubation time, ferrous and acid extractable iron were determined with Ferrozine assay by spectrophotometer in 562 nm (8, 25).
Results and Discussion: Results showed that the AQS had a noticeable effect on ferrous iron concentrations in both acidic and calcareous soils. In these cases ferrous iron concentrations were 8 and 15.7 times higher compared to initial concentration in acidic and calcareous soils, respectively. The Shewanella sp. intensified ferrous iron concentration 7.2 and 16.3 fold in acidic and calcareous soils, respectively but P. aeruginosa increased it 5.6 and 12.1 fold compared to initial concentration of ferrous iron. In acidic soil, in the presence of Shewanella sp. and AQS, ferrous and acid extractable iron concentrations were 1.45 and 4.50 mg g-1, respectively. Results showed that 11.7 fold enhancements occur in the presence of Shewanella sp. and AQS compared to initial (0.385 mg g-1) concentration of iron in acidic soil. When P. aeruginosa was inoculated in acidic soil in the presence of AQS, soluble ferrous iron concentration was 1.27 mg g-1. The acid extractable iron in this treatment was 2.85 mg g-1. The concentration of soluble ferrous iron in calcareous soil was 0.81 mg g-1, when AQS was added to Shewanella sp. treatments. That value was 0.54 when P. aeruginosa was added. The acid extractable iron was 3.90 mg g-1 in the presence of AQS and Shewanella sp. By adding P. aeruginosa, acid extractable iron was 2.84 mg g-1 compared to control treatments.
Conclusions: Dissimilatory ferric iron reduction is a potentially important process in controlling contaminant fate. It has the potential for being particularly useful in the remediation of metals and radionuclides. Means for stimulating ferric iron reduction will be useful in enhancing bioremediation process. Results illustrated that the Shewanella sp. and P. aeruginosa were enhanced the bioreduction of ferric iron in the presence of AQS, humic acid and fulvic acid in soils. When soil samples were inoculated with Shewanella sp., and AQS was added to the soil samples (in acidic and calcareous soil samples) the concentration of ferrous iron increased intensively.
V. Feiziasl; A. Fotovat; A. Astaraei; A. Lakzian; M.A. Mousavi Shalmani; A. Khorasani
Abstract
Introduction: Nitrogen (N) is one of the most important growth-limiting nutrients for dryland wheat. Mineral nitrogen or ammonium (NH4+) and nitrate (NO3−) are two common forms of inorganic nitrogen that can serve as limiting factors for plant growth. Nitrogen fertilization in dryland area can increase ...
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Introduction: Nitrogen (N) is one of the most important growth-limiting nutrients for dryland wheat. Mineral nitrogen or ammonium (NH4+) and nitrate (NO3−) are two common forms of inorganic nitrogen that can serve as limiting factors for plant growth. Nitrogen fertilization in dryland area can increase the use of soil moisture, and improve wheat yields to some extent. Many researchers have been confirmed interactions between water stress and nitrogen fertilizers on wheat, especially under field conditions. Because of water stress affects forms of nitrogen uptake that leads to disorder in plant metabolism, reduction in grain yield and crop quality in dryland condition. On the other hand, use of suitable methods for determining nitrogen requirement can increase dryland wheat production. However, nitrogen recommendations should be based on soil profile content or precipitation. An efficient method for nitrogen fertilizer recommendation involves choosing an effective soil extractant and calibrating soil nitrogen (Total N, NO3− andNH4+) tests against yield responses to applied nitrogen in field experiments. Soil testing enables initial N supply to be measured and N supply throughout the season due to mineralization to be estimated. This study was carried out to establish relationship between nitrogen forms (Total N, NO3− andNH4+) in soil and soil profile water content with plant response for recommendation of nitrogen fertilizer.
Materials and Methods: This study was carried out in split-split plot in a RCBD in Dryland Agricultural Research Institute (DARI), Maragheh, Iranwhere N application times (fall, 2/3 in fall and 1/3 in spring) were assigned to the main plots, N rates to sub plot (0, 30, 60 and 90 kg/ha), and 7 dryland wheat genotypes to sub-sub plots (Azar2, Ohadi, Rasad and 1-4 other genotypes) in three replications in 2010-2011. Soil samples were collected from 0-20, 20-40, 40-60 and 60-80 cm in sub-sub plots in shooting stage (ZGS32). Ammonium measurement in the soil KCl extracts was down by spectrophotometry method and colorimetric reaction at 655 nm. Also, Absorption spectrophotometry method was used for determination of nitrate in soil extract based on its UV absorbance at 210 nm. In this method two measurements were carried out; one before (by Zn coated by Cu) and second after reduction of nitrate). Using the difference between these two measurements, concentration of nitrate in the extracts was determined. Soil water content was also measured with Diviner 2000 after calibration in 0-20, 20-40, 40-60 and 60-80 cm soil profile in sub-sub plots. After wheat harvest, the most suitable regression model between soil mineral nitrogen (Nm) and soil moisture (θ) was fitted with wheat grain yield by DataFit version 9.0 software.
Results and Discussion: The best model between soil N forms (nitrate, ammonium and mineral nitrogen) was calibrated between mineral nitrogen (Nm) and soil moisture (θ) with crop response (Y=a+bN_m+c ln〖(θ)〗+dN_m^2+eln〖(θ)〗^2+fN_m ln〖(θ)〗) that explained 80% of dryland wheat yield variations. In this model, the contributions of mineral nitrogen (NO3− +NH4+) were 26%, soil moisture 50% and their interactions 24%. According to this model, the effect of soil moisture on production of grain yield was 2.3 folds greater than the mineral N. These results are most suitable for sampling and calibration of mineral nitrogen in 0-40 cm in dryland wheat stem elongation (ZGS32). Critical value of soil mineral N was 41 kg/ha, equal to 18.0 mg Nm/kg in this layer for obtaining higher grain yield (over 2500 kg/ha). According to regression model, application of 50 kg N/ha in autumn was able to provide Nm critical level in 0-40 cm layer for dryland wheat genotypes under experimental conditions. Also simulation model showed that nitrogen fertilizer increased grain yield and it is more than the soil mineral nitrogen. If the soil mineral nitrogen is 20 kg/ha or less in 0-40 cm soil layer, there may be increase of grain yield up to 4000 kg/ha through the application of nitrogen fertilizers. Therefore, increasing of mineral nitrogen in the soil profile up to 20 kg/ha is not appropriate for wheat production in Northwest of Iran drylands.
Conclusion: It can be concluded that, there is a relationship between soil nitrogen and moisture content with dryland wheat response and suggested model can be used for nitrogen recommendations for dryland wheat. According to the model, the effects of nitrogen fertilizer application on grain yield were much more than the effect of soil mineral nitrogen. Therefore, the increasing of soil nitrogen storage is not recommended in dryland conditions.
Saeed Bagherifam; A. Lakzian; A. Fotovat; R. Khorasani
Abstract
Introduction: Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised ...
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Introduction: Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised serious environmental concerns. Nearly all Arsenic-contaminated soils results from human activities and it has different environmental and sociological impacts. Various strategies and methods have been proposed for environmental management and remediation of contaminated soils. Among all methods, the phytoremediation is receiving more attention due to its cost effective and environmental friendly characteristics. In the case of arsenic contaminated soils, there are effective factors such as soil fertility, nutrients content and microorganisms function, which can improve the uptake of As by plants. Up to now, several studies have been evaluated the effects of symbiotic fungal association in plants on increasing nutrients and toxic elements uptake. Many of authors reported that the mycorrhizal symbiosis increases the uptake of toxic elements in root and shoot of plants and consequently improve the efficacy of phytostabilization and phytoextraction processes. There are conflicting results about the effect of arbuscular- mycorrhizal fungi (AMF) on As uptake by various plants. Chen et al. (4) found that Glomus mosseae symbiosis with plant reduces As concentration and enhance phosphorus content in shoot and root of plant. Whilst Cozzolino et al. (7) reported that the AMF increases as concentration in shoot and root of cabbage. Phosphorus has important role on mycorrhizal symbiosis and also As uptake by plants. Therefore, current study was conducted to evaluated effect of Glomus intraradices and Glomus mosseae symbiosis with sunflower and also soil phosphorus concentration on uptake of arsenic from arsenite and arsenate contaminated soils.
Materials and Methods:The soil sample (Typic Haplorthids) was collected, air dried and passed through 2 mm sieve and then were heated in 80 centigrade degree temperature for two times. A pot experiment was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition. The experimental factors included two species spices of inorganic As (50 mg kg-1 of Arsenite and Arsenate), two levels of phosphorus (0 and 60 mg Kg-1) and three spices of arbuscular mycorrhizae (control, Glomus intraradices and Glomus mosseae). Soil samples spiked with Na2HAsO4.7H2O, NaAsO2 (Arsenite and Arsenate) and Ca (H2PO4)2 (phosphorus) and incubated in greenhouse condition for 4 week. Sunflower seeds were planted and seedlings harvested after 60 day of sowing and then dry weight of sunflower, concentration of As and phosphorus in shoot and root of plant and root colonization percentage determined using standard methods.
Results and Discussion:The results revealed that Glomus intraradices (GI) and Glomus mosseae (GM) symbiosis significantly (P
H. Asadi Rahmani; A. Lakzian; J. Ghaderi; P. Keshavarz; H. Haghighatnia; K. Mirzashahi; M. R. Ramezanpour; A. Charati Arayi; A. Mohammadi Torkashvand
Abstract
Intoduction: Plant growth promoting rhizobacteria (PGPR) are a diverse group of bacteria consisting different species like Pseudomonas, Azotobacter, Azospirillum, Flavobacterium, Bacillus and Serratia with ability of enhancing plant growth and yield by different mechanisms. Flavobacteria are aerobic, ...
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Intoduction: Plant growth promoting rhizobacteria (PGPR) are a diverse group of bacteria consisting different species like Pseudomonas, Azotobacter, Azospirillum, Flavobacterium, Bacillus and Serratia with ability of enhancing plant growth and yield by different mechanisms. Flavobacteria are aerobic, gram negative, rod shape bacteria with more than 100 species living in different habitats ranging from soil and water to the foods. There are reports indicating that Flavobacteria are of dominant rhizosphere bacteria with beneficial effects on agricultural crops. Studies in Iran showed that six species of Flavobacterium were isolated and identified from rhizosphere of wheat. The aim of this study was to evaluate the effect of four strains of Flavobacterium on growth and yield of wheat under field conditions.
Materials and Methods: In this study four strains of Flavobacterium F9, F11, F21 and F40 were used. Bacterial strains were propagated in liquid NB growth medium and were used in field experiments. Fields were prepared in Khorasan Razavi, Khuzestan, Fars, Mazandran and Kermanshah and wheat seeds were inoculated with strains and sowed in a randomized complete block design (RCBD) with five treatments (four strains and a un-inoculated control) with four replications. Wheat varieties were Pishtaz in Khorasan and Fars, Marvdasht in Kermanshah, Chamran in Khuzestan and Milan in Mazandaran. Chemical fertilizers were used based on soil analysis. The rate of inoculation was 10 ml of bacteria per kg of seed. Plants were harvested at the end of the experiment and seed yield, total shoot biomass, 1000-seed weight, plant height, number of panicles per m2, number of seeds per panicle and panicle length were measured. Data analysis was performed by SPSS software, and the means were compared at α꞊5% by Duncan test.
Results and discussion: Results of the study showed that bacterial strains increased growth and yield of wheat in all provinces. In Mazandaran, all strains promoted seed yield although the effect of F21 was not significant. F40 had the highest effect on factors measures in the study. In Khuzestan, inoculation had no significant effect of seed yield production, although yield production was increased compared to control treatment. There was a similar trend regarding to other factors. In Khorasan, all factors were increased except for seed yield and 1000-seed weight due to inoculation with Flavobacterium strains. In Fars, inoculation with strain F40 significantly increased seed yield production by 11.5% compared to control treatment. In Kermanshah, seed yield, total biomass and plant height were significantly affected by inoculation with bacterial strains. Results showed that strain F40 was the most effective strain to increase yield of wheat. This study showed that Flavobacterium as a PGPR bacteria is able to positively affect the growth of wheat in Iran. This is in agreement with experiments in other parts of the world. In Khuzestan, bacteria were not effective on growth of wheat probably due to high soil temperature in this province compared to other provinces.
Conclusions: This study revealed that Flavobacteria are present in rhizosphere of wheat in Iran and could improve growth characteristics and yield of wheat in field experiments. Finally, strain F40 was the superior strain which increased seed yield by 15 % compared to control treatment.
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 ...
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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
H. Karimi; A. Lakzian; Gh. haghnia; H. Emami; M. Soufi
Abstract
Introduction: Soil erosion by water is one of the most widespread forms of land degradation and it has caused many undesirable consequences in last decades. On steep slopes, rill erosion is the most important type of erosion, which produces sediment and rill flow. It can be also considered as a vehicle ...
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Introduction: Soil erosion by water is one of the most widespread forms of land degradation and it has caused many undesirable consequences in last decades. On steep slopes, rill erosion is the most important type of erosion, which produces sediment and rill flow. It can be also considered as a vehicle for transporting soil particles detached from upland areas. Recent studies indicate that soil detachment rates are significantly influenced by land use. It is also known that there is a major difference between detachment rates of disturbed and natural soils (Zhang et al., 2003). Plowing rills especially in steep slopes increases sediment production. Sun et al. (2013) reported that the contribution of rill erosion in hill slope lands in china was more than 70%, which was approximately 50% of total soil erosion. In addition, measured soil loss is statistically related to hydraulic indicators such as slope, water depth, flow velocity, flow shear stress and stream power (Knapen et al., 2007). This study aims to evaluate the effects of hydraulic variables (shear stress and stream power) on spatial-temporal soil detachment rate. The focus is on the plowing rills in hillslope areas under wheat dry farming cultivation.
Materials and Methods: The study area is located in hilly slopes with the slope of 22.56% under dry farming wheat cultivation at 60 km of west of Shiraz, Iran. Top-down conventional plowing was carried out in order to create 10 meters furrows. Slope and cross sections of rills were measured throughout the experiment at 1 m intervals by rill-meter. Water was added to the top of the rills for 10 minutes and inflow rates were 10, 15 and 20 L min-1. Hydraulic parameters such as shear stress and stream power were calculated measuring rill morphology and water depth. Flow velocity and hydraulic radius along the different rill experiments were also calculated. Sediment concentrations were measured in three equal regular time and distance intervals (measurement points (MPs)), they were considered to calculate sediment detachment rate in different times and sections of each rill experiment for spatial and temporal soil detachment rate evaluation. One-way analysis of variance (ANOVA) was employed to test the significance of differences of sediment detachment rate among different treatments.
Results and Discussion: The results showed that the maximum values of shear stress and stream power were 14.07 Pa and 10.29 Wm-2 and the minimum values were 7.41 and 2.77 respectively. This research also indicated that changes in longitudinal profile of these hydraulic parameters along the rills affected the soil detachment rate values. Obtained average, minimum and maximum of the soil detachment rate were determined as 0.09, 0.02 and 0.22 kgm-2s-1, respectively. Due to Detachment-Transport Coupling mechanism, there was a significant difference between the initial and following MPs (P
S. Akbari; Ali reza Karimi; A. Lakzian; A. Fotovat
Abstract
Introduction: Parent materials as one of the main soil formation factors have a great impact on the concentration of heavy metals in the soil. Heavy metals are released to the soil during weathering and pedogenic processes. Ultrabasic rocks are known as the potential natural source of heavy metals, especially ...
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Introduction: Parent materials as one of the main soil formation factors have a great impact on the concentration of heavy metals in the soil. Heavy metals are released to the soil during weathering and pedogenic processes. Ultrabasic rocks are known as the potential natural source of heavy metals, especially Ni, Cr and Mn in the soil. Average concentrations of Ni and Cr in the soils are 84 and 34 mg kg-1, respectively; while, in soil derived from ultrabasic parent material, the concentration of these elements may reach up to 100000 mg kg-1. Binaloud zone in northeastern composed of different geological materials. There is a narrow band of ophiolitic rocks in this zone that located along Mashhad city. The geochemical behavior of ultrabsic rocks and the associated soil have been frequently studied mostly in humid regions. But, there are a few research works done in arid environments. The objective of this study was to investigate the physical and chemical properties and concentrations of Ni, Cr and Mn in soils formed along a toposequence of ultrabasic rocks in western Mashhad.
Materials and Methods: The study area is located in the hilly land landscape of Binaloud zone in the Western part of Mashhad. Mean annual precipitation and temperature is 260 mm and 13.7 oC, respectively. Soil temperature and moisture regimes are thermic and aridic boarder on mesic, respectively. Studied soils developed on hornblendite rocks that are ultrabasic rocks with SiO2 less than 45% and contain ferromagnesian minerals. A toposequence was selected and, three soil profiles on shoulder, backslope and footslope geomorphic positions were described acoording to key to soil taxonmy 2014 and the soil horizons were sampled. Air-dried samples were passed through 2 mm sieve and were used for laboratory analysis. Pseudo-total concentrations of Ni, Cr and Mn were extracted by aqua regia digestion procedure. Free iron oxides (Fed) and amorphous iron oxides (Feo) were extracted by citrate-bicarbonate-dithionite (CBD) and oxalic acid methods, respectively and were measured by atomic absorption spectroscopy. The soil was extracted by ammonium acetar 1N and concentration of Ca and Mg were measured by EDTA titrimetric method. Calcium carbonate equivalent, gypsum, pH, Sand, silt and clay fractions and soil organic materials were measured using custom laboratory methods.
Results and Discussion: Solum thickness of the studied soils is less than 45 cm. Calcification and gypsification are the two main soil formation processes leading to formation of calcic (Bk) and gypsic (By) horizons. Calcium carbonate equivalent and gypsum contents in the studied soils varied from 5.1 to 30 and 5.9 to 40.1 %, respectively. Regarding the type of parent material, presence of large amounts of gypsum and carbonates can be attributed to aeolian addition to the soil system. The presence of discontinuous and thin loess deposits in the study area confirms the dustfall deposition. High amount of these minerals cause Ca/Mg ratio is up to 33.3. Concentration of Fed and Feo were less than 6.8 and 0.2 g kg-1 reflecting weak wethering state of the soils. Morphological characteristics are the indications of weak soil development and weathering. Concentrations of Ni, Cr and Mn varied from 52.6 to 312.5, 35.2 to 135.3 and 375.3 to 628.9 mg kg-1 that are low values in comparison to soils in humid regions due to weak soil weathering and eolian addition of materials containing gypsum and carbonates. The Ni and Cr contents increase from shoulder to foot slope. Direct and concordant variations of Ni with Cr and Mn with Fed indicate the similar mineralogy and trend of weathering of these elements. Regarding the high concentration of Ni and Cr in the studied soils, the bioaccessibility of these elements should be investigated.
Conclusion: Results of this study indicated the weak development of soil formed on ultabasic rocks in the western Mashhad that was expected regarding the arid climate of the study area. Because of the low weathering status of the soil, the concentration of Ni, Cr and Mn were less than that of similar soils in humid areas. Also aeolian addition of carbonates and gypsum to the soil system dilutes the concentration of these elements. To evaluate risk assessment of Ni, Cr and Mn in the studied soils, successive extraction and pot experiments are suggested.
ghodsie hoseinian rostami; Ahmad Gholamalizadeh Ahangar
Abstract
Adding heavy metals to soils leads to change of their original distribution pattern. Heavy metals distribution in soils depends upon heavy metal, application level, application time and soil characteristics as well. This investigation was conducted to assess the time effect on distribution of different ...
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Adding heavy metals to soils leads to change of their original distribution pattern. Heavy metals distribution in soils depends upon heavy metal, application level, application time and soil characteristics as well. This investigation was conducted to assess the time effect on distribution of different fractions of Lead in soils. The experiment conducted as a factorial in a completely randomized design with three replications and two levels of cow manure (0 and 5%) and two levels of Lead using Lead nitrate (0 and 200 mg kg-1). Samples were incubated at 250C and 60% of field capacity for 120 days with different time intervals (0-30, 0-60, 0-90 and 0-120 day) to determine Lead fractions using sequential extraction methods. The results showed that Lead concentration decrease in exchangeable, carbonated and residual fractions during the time. Also the interactions between cow manure and time cause of decreases in the exchangeable and residual fractions and increases in the carbonated, Fe-Mn oxides-bound as well as organic matter-bond fractions. The interactions between time and Lead concentration lead to decrease in the exchangeable, carbonated and residual fractions and increase in the Fe-Mn oxides-bound and organic matter-bond Lead fractions. Since the most availability and toxic potential of lead is in the exchangeable-solution, the advantage of the this study is to reduce potion of this section during the time.
M.A. Mousavi Shalmani; A. Lakzian; A. Khorasani; V. Feiziasl; A. Mahmoudi; A. Borzuee; N. Pourmohammad
Abstract
In order to assessment of water quality and characterize seasonal variation in 18O and 2H in relation with different chemical and physiographical parameters and modelling of effective parameters, an study was conducted during 2010 to 2011 in 30 different ponds in the north of Iran. Samples were collected ...
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In order to assessment of water quality and characterize seasonal variation in 18O and 2H in relation with different chemical and physiographical parameters and modelling of effective parameters, an study was conducted during 2010 to 2011 in 30 different ponds in the north of Iran. Samples were collected at three different seasons and analysed for chemical and isotopic components. Data shows that highest amounts of δ18O and δ2H were recorded in the summer (-1.15‰ and -12.11‰) and the lowest amounts were seen in the winter (-7.50‰ and -47.32‰) respectively. Data also reveals that there is significant increase in d-excess during spring and summer in ponds 20, 21, 22, 24, 25 and 26. We can conclude that residual surface runoff (from upper lands) is an important source of water to transfer soluble salts in to these ponds. In this respect, high retention time may be the main reason for movements of light isotopes in to the ponds. This has led d-excess of pond 12 even greater in summer than winter. This could be an acceptable reason for ponds 25 and 26 (Siyahkal county) with highest amount of d-excess and lowest amounts of δ18O and δ2H. It seems light water pumped from groundwater wells with minor source of salt (originated from sea deep percolation) in to the ponds, could may be another reason for significant decrease in the heavy isotopes of water (18O and 2H) for ponds 2, 12, 14 and 25 from spring to summer. Overall conclusion of multiple linear regression test indicate that firstly from 30 variables (under investigation) only a few cases can be used for identifying of changes in 18O and 2H by applications. Secondly, among the variables (studied), phytoplankton content was a common factor for interpretation of 18O and 2H during spring and summer, and also total period (during a year). Thirdly, the use of water in the spring was recommended for sampling, for 18O and 2H interpretation compared with other seasons. This is because of function can be explained more by variables and there are more variables compare with other two seasons. Fourthly, potassium concentration in spring and total volume of water in summer would be most appropriate variables for interpretation of data during these seasons
T. Javaheri; A. Lakzian; P. Taheri; R. Khorasani
Abstract
Organic phosphorus is the dominant part of soil phosphorus. Phytic acid and sodium Glycerophosphate are two different forms of soil organic phosphorus. Soil fungi play an important role in the conversion of these compounds into inorganic forms. Among the fungi, Aspergillus is one of the most effective ...
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Organic phosphorus is the dominant part of soil phosphorus. Phytic acid and sodium Glycerophosphate are two different forms of soil organic phosphorus. Soil fungi play an important role in the conversion of these compounds into inorganic forms. Among the fungi, Aspergillus is one of the most effective organisms in hydrolysis of organic compounds. In order to study the ability of Aspergillus fungi on the hydrolysis of Phytic acid and sodium Glycerophosphate, an experiment was conducted as a completely randomized design with factorial arrangement and three replications. The first experimental factor include five fungi isolates (four Aspergillus isolates, Trichoderma harzianum and control) and the second factor include two different organic phosphorus compounds (Phytic acid and Sodium Glycerophosphate). All isolated were grown in PDB at 28 oC and rate of hydrolysis of inorganic phosphorus was determined after 14 days inoculation. In addition, acid and alkaline phosphatase activity and medium pH were measured. The results showed that Aspergillus isolates and Trichoderma harzianum mineralized organic phosphorus significantly (p
V. Feiziasl; A. Fotovat; A. Astaraei; A. Lakzian; M.A. Mousavi Shalmani
Abstract
In order to determination of water stress threshold and dryland wheat genotypes water status in different nitrogen managements, this experiment was carried out in split split plot RCBD design in three replications in 2010-2011 cropping year. Treatments included: N application time (whole fertilization ...
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In order to determination of water stress threshold and dryland wheat genotypes water status in different nitrogen managements, this experiment was carried out in split split plot RCBD design in three replications in 2010-2011 cropping year. Treatments included: N application time (whole fertilization of N at planting time , and its split fertilization as 2/3 at planting time and 1/3 in early spring), N rates (0, 30, 60 and 90 kg ha-1) and 7 wheat genotypes. Also these genotypes were grown in supplemental irrigation condition for calculation of crop water stress index (CWSI) parameters. Canopy temperature (Tc) was measured in flowering and early milking stages. Crop water stress index (CWSI) was calculated. A non-water stressed baseline (lower baseline) were fitted as Tc-Ta=4.523-3.761×VPD; R2=0.92 and non-transpiring baseline (upper baseline) determined 6 ºC for rainfed wheat genotypes. Water stress threshold was 0.4 and crossing of that occurred 8 days before heading stage. In water stress threshold boundary, was depleted 60 mm available water from 0 to 50 cm soil depth. There was negative significant relationship (p >0.01) between CWSI and grain yield in all treatments and different nitrogen rates. Nitrogen application reduced water stress and increased grain yield of rainfed wheat genotypes. Ohadi and Rasad genotypes showed highest resistance to water stress and high grain yield production for N30 in split and planting time application, respectively. Cereal4 and Rasad genotypes were suitable for N60 application in split and planting time application, respectively.
S. Saeidi; A. Fotovat; A. Lakzian
Abstract
The biodegradation of normal-hexadecane by bacteria is one of the important aspects of bioremediation.
The aim of this study was to investigate degradation of normal hexadacane (with level of contamination,
2500 mg.kg-1) by Pseudomonas aeruginosa, Pseudomonas putida and native bacteria of contaminated ...
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The biodegradation of normal-hexadecane by bacteria is one of the important aspects of bioremediation.
The aim of this study was to investigate degradation of normal hexadacane (with level of contamination,
2500 mg.kg-1) by Pseudomonas aeruginosa, Pseudomonas putida and native bacteria of contaminated regions in the presence of NPK (three types of fertilizer: urea with 46% nitrogen, ammonium phosphate with 21% nitrogen and 46% phosphor and potassium sulphate with 40% potassium) as nutritious source. The experiment was carried out as a completely randomized design (CRD) with factorial arrangement in three replications. Experimental factors included six levels of bacteria (Pseudomonas aeruginosa, Pseudomonas putida, three strains from contaminated regions Ahvaz, Sarakhs and Tehran and control), three levels of fertilizers treatment (0 and 2 ton.ha-1 of NPK) and two levels of soil condition (sterile and non-sterile) at two times (30 and 60 days). Then, soil total organic carbon (TOC) as index for the degradation of normal hexadacane in samples was measured. The results showed that degradation of normal hexadecane in sterilized soil samples were higher than non sterilized soil samples. the highest degradation of normal hexadecane was observed in the presence of Sarakhs strain. The amount of degradation by this strain with nutritious source was 45% whereas this value was lower (one third) in the absence of NPK. Moreover, the results indicated that the amount of degradation by the bacteria increased with time. Biodegradation value in the presence of NPK was 4-fold higher compared to no-NPK treatment after 60 days.
nasrin ghorbanzadeh; A. Lakzian; Gh. Haghnia; Ali reza Karimi
Abstract
Microbial reduction is an important process that affects properties of ferric clay mineralas and iron biogeochemical cycling in natural environments. Oxyhydroxides and phyllosilicates are two major sources of iron in soils, rocks and sediments that potentially have ability to bioreduced over the time. ...
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Microbial reduction is an important process that affects properties of ferric clay mineralas and iron biogeochemical cycling in natural environments. Oxyhydroxides and phyllosilicates are two major sources of iron in soils, rocks and sediments that potentially have ability to bioreduced over the time. In this study, comparison of bioreduction in two main sources of iron (oxides and phyllosilicates) in the presence of Shewanella sp was carried out. For this purpose an experiment was conducted under laboratory conditions in the form of a completely randomized design with 16 treatments and 3 replications. Treatments included bioreduction of goethite, hematite and two type of nontronite with and without electron transfer (AQS) and controls (all mentioned treatments in the absence of Shewanella sp). The results revealed that bioreduction in goethite, hematite and two type of nontronite increased in the presence of AQS. The extent of reduction in the presence of AQS was 21%, 9%, 3% and 8.7% in NAu-2, NAu-1, hematite and goethite respectively. These results have shown when iron oxides (goethite and hematite) and iron silicates are the dominant form of ferric iron in soils and subsurface sediments, Shewanella sp can survive and produce significant amounts of Fe(II). In the identical conditions of bioreduction (concentration of electron donor and acceptor and equal number of bacterial cell) size and surface area of mineral play an important role in efficiency of bioreduction.
A. Lakzian; M. Fazeli Sangani; Alireza Astaraei; A. Fotovat
Abstract
This study was conducted to evaluate using terrain attributes derived from digital elevation model (DEM) as ancillary data to predict soil organic carbon (SOC) by implementing different statistical and geostatistical techniques. A linear regression model (LR), Artificial Neural Network model (ANN), ordinary ...
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This study was conducted to evaluate using terrain attributes derived from digital elevation model (DEM) as ancillary data to predict soil organic carbon (SOC) by implementing different statistical and geostatistical techniques. A linear regression model (LR), Artificial Neural Network model (ANN), ordinary kriging (OK), ordinary co-kriging (OCK), regression kriging (RK) and kriging with an external drift (KED) were performed to predict spatial distribution of SOC in an area of 2400 km2 in mashhad, iran. The SOC was measured for 200 soil samples of the study area and their corresponding Terrain attributes value was extracted from derived from 10-m resolution DEM. correlation between measured SOC and individual terrain attributes was determined, the number of 160 data were used for model development and 40 as validation data set. Resulting maps of different interpolation methods were compared to evaluate map quality using MAE and R2 criteria calculated from plotting measured versus estimated data. The results showed that there is a significant but not strong correlation between SOC and terrain attributes. The comparison of estimation techniques showed that the KED technique with wetness index as ancillary data has the best performance (MAE=0.18 %, R2=0.67) of all, but no significant difference with RK. There were modest differences between maps created with geostaistical technique but sensible difference with LR and ANN ones. The results of this study propose that although there is a significant correlation between SOC and terrain attributes therefore It can be use for enhancing the quality of map, but it is not able to express the spatial variability of SOC as it is necessary for detailed soil map. Because there is other factors controlling SOC spatial distribution