N. Mehrab; M. Chorom; M. Norouzi Masir
Abstract
Introduction: Decontamination of heavy metals (HMs), especially cadmium (Cd) which has high mobility in the soil, is very important due to the effects of HMs pollution on the soil, environment, and human. Numerous efforts have been made to develop technologies for the remediation of contaminated soils, ...
Read More
Introduction: Decontamination of heavy metals (HMs), especially cadmium (Cd) which has high mobility in the soil, is very important due to the effects of HMs pollution on the soil, environment, and human. Numerous efforts have been made to develop technologies for the remediation of contaminated soils, including ex-situ washing with physical-chemical methods, and the in-situ immobilization of metal pollutants. These methods of clean up are generally very costly, and often harmful to properties of the soil (i.e., texture, organic matter, microorganisms). Recently, the phytoremediation of HMs from contaminated soils has attracted attention for its low cost of implementation and many environmental benefits. Several chelating agents, such as DTPA, EDTA, and NTA, have been studied for their ability to dissolve metals, leach heavy metals, and enhance the uptake of metals by plants. Although many researchers have reported that EDTA is excellent solubilizing agents for HMs from contaminated soils, it is quite persistent in the environment due to the low biodegradability. Hence recently the easily biodegradable chelating agent NTA has been proposed to enhance the uptake of HMs in phytoremediation as well as the leaching of HMs from the soil. Therefore, in the present study attempts are made to investigate the effect of applicability NTA in Cd leaching and the refining of Cd from contaminated-soil by maize.
Materials and Methods: In this research, the effect of NTA on Cd leaching and its absorption by maize in contaminated-soil in a greenhouse experiment were investigated. The experiment was a factorial experiment based on a completely randomized design. The treatments consisted of three levels of Cd contamination (0, 25 and 50 mg kg-1soil) and three levels of NTA (0, 15 and 30 mmol per pot) in loamy soil and in the cultured and non-cultured conditions under three irrigation conditions. The soil was contaminated with cadmium chloride (CdCl2.2.5H2O). Nitrogen, phosphorus, and potassium (in the form of urea, triple superphosphate and potassium phosphate, respectively) were added to the pots. NTA was added in three steps to the pots. The first step of adding NTA was beginning 4 weeks after cultivation, occurring approximately once in 14 days. Also, 7 days after adding NTA, the pots were irrigated with an amount corresponding to 20% more water than the moisture of soil saturation condition. The drainage water collected from each irrigation event was kept in a refrigerator at 5°C prior to Cd analysis. The plants were cut about 5 mm above the soil surface after 10 weeks of maize growth and were dried for analyzing Cd in the plant. Analysis of variance was used to study the effects of different treatments of Cd and NTA on Cd contents in drainage water, plant, and soil. Statistical analysis were performed using SPSS. Means of treatments were compared using Duncan’s Multiple Range Test (DMRT) and the graphs were plotted in Excel.
Results and Discussion: The contrasting impact between irrigation rounds and Cd treatments, as well as NTA treatments on Cdtotal leached was significant (P<0.05). The highest Cd leached was in 50 mgCd kg-1soil (Cd50) and 30 mmol NTA (NTA30) in the first irrigation round. In the next two rounds, the Cd leached from the soil was inconsiderable. Different levels of Cd and NTA showed a significant difference in Cd concentration in the first round of leaching. In non-cultivated pots, the amount of Cd leaching in Cd50NTA15 and Cd50NTA30 treatments increased by 8 and 15 times, respectively than that in Cd50NTA0 treatment. In the case of similar treatments in the presence of maize, the Cd leaching rate increased by 5.8 and 6 times, respectively, than that in (NTA0). Cd absorbed by maize in (Cd50, NTA30) was maximum and that measured 58% more than that in (Cd50, NTA0), while dry weight decreased significantly (30% in the shoot and 40% in the root). After the cultivation and leaching process, the maximum amount of DTPA-extractable Cd was observed in (Cd50, NTA0). While using (NTA15, NTA30) at the same level of Cd-contamination (Cd50), there was a significant decrease in DTPA-extractable Cd (due to the increase in Cd dissolved, Cd leached and Cd absorbed by plants). Due to pH between 2-3 and EC about 2.5-3.5 in NTA solutions, the application of NTA in soil decreased pH and increase EC in the soil. On the other hand, the decrease in pH of soil increased solubility of calcium carbonate equivalent (CCE), thereby reduced CCE in the soil. The results of this study showed that the soil pH was effective on HMs absorption by plants, therefore the availability of Cd after the use of NTA may be due to the decrease of alkalinity in the soil. The presence of organic-metal bonds in chelate-metal compounds causes metals to be less exposed to colloids, hydroxides, and oxides thus will prevent their stabilization in the soil. So it can be said that one of the effective methods for increasing the absorption of HMs from the soil by the plant is to reduce the pH of the soil. Some of the soil properties, such as pH and total heavy metal concentration, improves the efficiency of the chelator agent.
Conclusion: The results showed that an increase in the amount of Cd contamination and NTA applied increased Cd content in drainage water and Cd which was uptake by maize. Also, results showed well, the combined of maize planting and the use of NTA is successful in refining Cd from contaminated-soil. It seems that Adding NTA as a natural chelator in Iranian calcareous soils can increase the dissolution of Cd and extract it from the soil during a leaching period without contamination of the environment, as well as increase the efficiency of removing Cd by maize.
Akbar Karimi; abdolamir moezzi; Mostafa Chorom; Naeimeh Enayatizamir
Abstract
Introduction: Zinc is a key micronutrient which takes part in plant physiological functions. One of the extensively wide range abiotic stresses arises from Zn shortage in agricultural calcareous soils. Zn is one of the most prevalent disorders among various crops. Zinc deficiency is very common in most ...
Read More
Introduction: Zinc is a key micronutrient which takes part in plant physiological functions. One of the extensively wide range abiotic stresses arises from Zn shortage in agricultural calcareous soils. Zn is one of the most prevalent disorders among various crops. Zinc deficiency is very common in most calcareous soils. Different mechanisms are involved in the deficiency of Zn In calcareous soils. The presence of calcium carbonate, lack of organic matter and high pH lead to Zn deficiency. Knowledge on the total Zn contents of in soil gives little information for their bioavailability. In order for better understanding availability of Zn to plant, knowledge about their mobility, and distribution in soil fractions is necessary. Biochar is a carbon-rich material produced by pyrolysis of biomass under oxygen-limited conditions and relatively low temperature. Biochar as a valuable soil amendment has received much attention due to its beneficial effects on carbon sequestration, soil physiochemical properties, soil microbial activity as well as soil fertility. Pyrolysis temperature has a significant influence on biochar physicochemical properties. Furthermore, biochar may alter the distribution of Zn fractions in calcareous soils. The impact of produced biochars at different pyrolysis temperature on distribution of Zn fractions in calcareous soils has been less studied. Therefore, the objective of this research was to evaluate the changes in distribution of Zn fractions in a calcareous soils treated with sugarcane bagasse derived biochars at different pyrolysis temperature.
Materials and Methods: An incubation experiment was carried out in laboratory condition as a factorial experiment based on a randomized complete design with two factors: (1) biochar type in four levels including control (without biochar) and biochar produced at 200 (B200), 350 (B350) and 500 ˚C (B500), (2) biochar application rate in two levels including 1 and 2% (w/w), and in three replications. Biochars were produced at 200, 350 and 500˚C pyrolysis temperatures under slow pyrolysis conditions with a heating rate of 5 °C min−1. Heating at this temperature lasted for 2 h. Then biochars were sieved to pass through 2 mm sieve and some properties were measured using the standard methods. The soil used in this study was sampled from the surface layer (0 to 20 cm depth), then, air-dried and sieved through 2 mm. Biochars produced at 200, 350 and 500˚C were mixed at 1 and 2% (w/w) with the 300 g of soil sample and incubated in ambient temperature at laboratory conditions (25 ± 2°C), for 90 days. Soil moisture content was maintained at 80% of field capacity. The samples were weighted every day and the required amounts of distilled water were added. At the end of incubation period, soil samples were air-dried and soil chemical parameters such as pH, cation exchange capacity (CEC), total organic carbon (TOC) and dissolved organic carbon (DOC) were measured.Chemical fractions of Zn in the incubated soil were determined according to the Tessier fractionation method. The Tessier sequential extraction method categorized Zn into 5 different fractions including: the exchangeable (Exch), bound to carbonate fraction (Car), bound to organic matter (OM), bound to Fe and Mn-oxides (FeMnOx) and residual fraction (Res).
Results and Discussion: Result indicated that application of different biochars significantly increased soil CEC and TOC. Maximum CEC and TOC were measured in B200 and B350 treatments, respectively, while their minimum values were observed in control treatment. In B200 treatments (B200, 1% and B200, 2%), pH significantly decreased compared to control, while this value significantly increased in B350, 1% , B500, 1% and B500, 2% treatments. B350 1% treatment did not have a significant effect on the soil pH. Application of 1 and 2% B200 significantly enhanced DOC (23.9 and 38%, respectively), compared to the control, but increase of DOC in B350 and B500 treatments was not significant compared to the control. Results showed that concentration of exchangeable Zn fraction decreased by 9.3, 19.5 and 9.5 % in B350, 2%, B500, 1% and B500, 2% treatments, respectively, compared to the control. However, B200 treatments (B200, 1% and B200, 2%) caused a significant increase in concentration of exchangeable Zn fractions (12.5 and 21.6%) compared to the control. The concentration of OM and Car Zn fractions increased in all biochar treatments compared to control. The highest concentration of OM and Car Zn fractions was observed after application of 2% B200 and 2% B500, respectively. Results showed that application of B350 and B500 had no significant effect on concentration of FeMnOx Zn fraction, while, this concentration significantly increased after B200 was applied. There were no significant (P ≤0.05) differences in concentration of residual Zn fraction among all the biochar treatments. The mean comparison results showed that the concentration of residual Zn in B200 treatments was significantly (P ≤0.05) lower than B350 and B500 treatments. There were no significant differences in this concentration among B500, B350 and the control treatments. Results revealed that in all treatments, different Zn fractions in the soil were distributed in the following order: Res > FeMnOx > Car > OM > Exch. The largest effect of biochars on the change in distribution of Zn fractions of soil was observed at 2% application rate.
Conclusion: It can be concluded that biochar B200 application could be an effective amendment for improving chemical properties and conversion of Zn from less available fractions to fractions with more bioavailability in the calcareous soil. Moreover, the biochar produced at 350 and 500˚C is better suited for enhancing soil organic carbon and Zn stabilization in calcareous soil.
mostafa Pajohannia; Mostafa Chorom; Siroos Jafari
Abstract
Introduction: Iron is found in different forms in the soil. In the primary minerals, iron is found as Fe3+ or Fe2+ which converted to Fe2+ and released in unsuitable reduction conditions. Minerals such as sulfide or chlorine and bicarbonate can affect and change the different forms soil Fe. FeAs these ...
Read More
Introduction: Iron is found in different forms in the soil. In the primary minerals, iron is found as Fe3+ or Fe2+ which converted to Fe2+ and released in unsuitable reduction conditions. Minerals such as sulfide or chlorine and bicarbonate can affect and change the different forms soil Fe. FeAs these elements are abundance in groundwater or soil, they are capable to react chemically with Fe and change different Fe forms and also may deposit or even leach them by increasing its solubility in the soil. Water table fluctuation is a regular phenomenon in Khuzestan that Fe forms change under these situations. The study of Fe oxide forms and its changes can be applied for evaluation of soil development. Therefore, the aim of this study is the water table fluctuation and its quality effects, and some physio-chemical properties on Fe oxides forms in non-saline and saline soils in Khuzestan.
Materials and Methods: Soil samples were collected from two regions: saline (Abdolkhan) and non-saline (South Susa) regions. soil samples were collected from all horizons of 12 soil field studied profiles . The samples were analyzed for soil texture, pH, EC (soil: water ratio 1:5), organic carbon and aggregate stability (Kemper and Rosenau method). Fe forms also were extracted by two methods in all samples: di-tyonite sodium and ammonium oxalate extraction. Fe oxalate extracted was related to Feo (non crystal Fe) and Fed-Feo was related to Fec (crystalline Fe). The Fe content were determined by atomic absorbtion spectrophotometer (AAS). Data were analysis in SAS and Excel software and results were presented.
Results and Discussion: The results showed that texture were loamy sand to silty clay loam, OM was very poor (0.1-0.7%). The soil salinity was also 2.8-16.8 dS/m. Calcium carbonate equivalent was 38-40%. All pedons were classified in Entisols and Inceptisols according to Keys to soil taxonomy (2010). The results showed that the proportion of Fe with oxalate to di-tionite treatments was different regarding the salinity, texture, organic matters, cultivation and the water table fluctuation. The total Fe content in the middle layers had permanently increased due to the groundwater fluctuation levels and this caused the creation of mottle in this layer. All saline soils had saline subsurface water. The salinity has caused that the effective microorganisms have not been actived on the reduction processes in some profiles and the Fe deposit more in the Fe3+forms. The Fe was found more in non-crystal form in saline regions, but it was in the crystal form in non-saline regions which indicated the suitable conditions for Fe’s nodule formation. For example, when soil salinity decreased from 14.9 to 8.1 dS/m, Fec increased from 460.1 to 497.8 mg/kg soil. With increasing the amount of clay, and cultivation periods, the Fed content has also been increased. The Feo/ Fec ratio in undevelopted soils was higher than developed soils. This ratio was low in non-saline soil and was high for saline soil. this indicates that non-saline soil had more development than saline soils. The maximum amount (1.6) was belonged to saline soil and minimum was for no saline soils. With increasing in soil age, tillage periods and clay content this ratio was decreased., statistical analysis Also showed that there was significant difference between Fec and Feo in saline and no saline soils. Also, with increasing in salinity, Fec content decreased and Feo increased. aggregate stability was also increased with increasing Fec content.
Conclusions: The Feo content was more in surface of saline soil than subsurface when pedon was ponded and saturated from surface. Feo was very higher in saline soils than no saline soils. Fec had not significant difference between saline and nonsaline soils. Salinity decreased Fec and increased Feo content in soils. Feo/Fec ratio of saline soils was 4 to 5 times fold of non-saline soils. Increasing Feo/Fec ratio in saline soils and decreasing in this ratio in nonsaline soil showed that nonsaline soils had more development than saline soils. Organic matter was more effective in Feo and Fec contents in nonsaline soil than saline soils. Also, Fec content increased with increasing clay content in all horizons that this shows that mottling and more Fe concentration in nonsaline soils.
hamidreza boostani; mostafa chorom; abdolamir moezzi; najafali karimian; naimeh enayatizamir; mehdi zarei
Abstract
Introduction: Zinc (Zn) is an important nutrient element for humans and plants that controls many biochemical and physiological functions of living organisms. Zinc deficiency is common in high pH, low organic matter, carbonatic, saline and sodic soils. Salinity is a major abiotic environmental stresses ...
Read More
Introduction: Zinc (Zn) is an important nutrient element for humans and plants that controls many biochemical and physiological functions of living organisms. Zinc deficiency is common in high pH, low organic matter, carbonatic, saline and sodic soils. Salinity is a major abiotic environmental stresses that limits growth and production in arid and semi-arid regions of the world. Bioavailability of Zn is low in calcareous and saline soils having high levels of pH and calcium. Desorption of Zinc (Zn) from soil as influenced by biological activities is one of the important factors that control Zn bioavailability. Few reports on the effects of salinity on the availability and desorption kinetics of Zn are available. Rupa et al. (2000) reported that increasing the salt concentration led to increase Zn desorption from soil due to ion competition on soil exchangeable sites. Different kinetic equations have been used to describe the release kinetics of nutrients. Reyhanitabar and Gilkes (2010) found that the power function model was the best equation to describe the release of Zn from some calcareous soil of Iran, whereas Baranimotlagh and Gholami (2013) stated that the best model for describing Zn desorption from 15 calcareous soils of Iran was the first-order equation.less attention has been paid to kinetics of Zn release by DTPA extractant over time by inoculation of plant growth promoting rhizobacteria and mycorrhizae fungi in comination with soil salinity.The objective of this study was to evaluate the effect of plant growth promoting rhizobacteria (PGPR) and mycorrhizae fungi (MF) inoculation on release kinetic of Zn in a calcareous soil at different salinity levels after in cornplantation
Materials and Methods: A composite sample of bulk soil from the surface horizon (0-30 cm) of a calcareous soil from southern part of Iran was collected, air dried, passed through 2 mm sieve, and thoroughly mixed. Routine soil analysis was performed to determine some physical and chemical properties. The experiment was conducted in the greenhouse of agriculture college of Shahid Chamran University, Ahvaz, Iran. A factorial experiment as a completely randomized design with three replications was conducted in greenhouse conditions. The first factor consisted of salinity levels (0, 15 and 30 cmol(c) kg-1 salt supplied as a 3:2:1 Na:Ca:Mg chloride salts) and the second factor was microbial inoculation (without inoculation, fungi, bacteria, bacteria + fungi).Soil samples were extracted using DTPA extractant for periods of 0.5, 1, 2, 6, 12 and 24 hours. Cumulative Zn released (q) as a function of time (T) was evaluated using seven different kinetic models. A relatively high values of coefficient of determination (r2) and low values of standard error of estimate (SEE) were used as criteria for the selection of the best fitted models. Statistical analysis of data was done using MSTATC package (Mstatc, 1991). Comparison between means was performed using Duncan's multiple range test (DMRT) at the significant level of P < 0.05. Also, charts were drawn by excel computer package.
Results and Discussion: Investigation of Zn release patterns showed that the control and all treated soils had a uniform pattern of Zn release. Overall, Zn release patterns were generally characterized by an initial fast reaction at first two hours, followed by slower continuing reaction. It seems likely that the release of zinc is controlled by two different mechanisms. Two-step process of releases (rapid and subsequent slow) is attributed to the existence of places with different energy. The use of all microbial treatments increased the initial release of Zn compared to control. The most and the least Zn initial release observed in fungi-bacterial and bacterial treatment respectively. By application of all microbial treatments, Zn release rate declined compared to control and the lowest decrease observed in fungal treatment. In general, Zn initial release was increased and Zn desorption rate was decreased by increasing of salinity levels. Also, soluble and exchangeable forms of Zn had the highest influence on Zn release control.
Conclusions: Results showed that simplified Elovich, two constant rate and parabolic diffusion kinetics models showed good description of the Zn release. Based on the highest correlation coefficient and the lowest mean standard error of the estimate, simplified elovich determined as the best kinetic model. So it seems that the main mechanism controlling the Zn release in the tested soil is diffusion phenomena.
Amir Parnian; Mostafa Chorom; Nematolah Jafarzade Haghighy Fard
Abstract
Introduction: With increasing of population and the valuable water resource pollutions, a demand has been felt for new and inexpensive methods in order to remediation and improving of water quality. Cadmium is a trace element. In low concentration, this heavy metal is harmful to life, and considered ...
Read More
Introduction: With increasing of population and the valuable water resource pollutions, a demand has been felt for new and inexpensive methods in order to remediation and improving of water quality. Cadmium is a trace element. In low concentration, this heavy metal is harmful to life, and considered as a dangerous pollutant. Cadmium leads to pollution and reduction of water quality; sometimes even toxicity through contaminated sources such as wastewater (Agricultural, municipal and industrial). Phytoremediation with aquatic macrophytes is an effective and inexpensive method for improving water quality and wastewater. The aim of this study was to investigatethe cadmium phytoremediation by Ceratophyllumdemersum L. as a potential method for remediation of cadmium pollution in aquatic medium.
Materials and Methods: In this study, the remediation of cadmium pollution in aquatic medium monitored, within 14 days cultivation of coontail (Ceratophyllumdemersum L.). At first, for estimating the level of local wastewater cadmium pollutions, five-month cadmium concentration measurement of steel industrial wastewater and urban wastewater set. Then, plants collected from the irrigation channels of ShahidChamran University of Ahvaz. After finding the best pH of nutrient solution for Ceratophyllumdemersum L. growth by cultivating the plants in 2 liters pots filled by the solutions withthree different pH(5.5, 7 and 9.5) within three weeks; 12 grams of plants cultivated in 2 liters of Hoagland nutrient solution contaminated by cadmium(pH = 7). The initial contamination levels were setasfive different concentrations of cadmium (0, 1, 2, 4, and 6 mg l-1) with three replications. The cadmium concentrations of the pots were measured every day and on the last day of cultivation, plants wet weight, plants dry weight and Cd concentration in plants weremeasured. Then,biomass production, Cd bioconcentration factor (BCF), Cd uptake index, and Cd uptake percentage of plants were calculated. Standard deviations calculationand correlation and regression analysis were performed using Microsoft Office Excel2007 and SPSS 16. One-way ANOVA performed to identify significant differences in metal concentrations in the different treatments. Differences considered significant atp < 0.05.
Results and Discussion: Among three pH (5.5, 7 and 9.5) for plants cultivation, C. demersum L.grewbetter in pH = 7. In fact, the average amount of produced biomasses were 46.6 g (pH = 5.5), 79.6 g (pH = 7) and 68.4 g (pH = 9.5). Therefore, to investigate the Cd remediation, the pH of nutrient solution set equal to 7. The final Cd concentrations in nutrient solution for initial Cd concentrations of 1, 2, 4 and 6 mg l-1 were 0.30, 0.36, 2.76 and 3.85 mg l-11respectively. Moreover, the Cd uptake percentage after 14days cultivation of C. demersum L.in nutrient solution for initial Cd concentrations of 1, 2, 4 and 6 mg l-1 were 70.00, 82.01, 31.00 and 35.83 %respectively. Cd uptake percentage of plants for initial concentrations of 4 and 6 mg l-1weresignificantly lesser than those of 1and 2 mg l-1.The decreased uptake efficiency percentage maybe caused by the effect of Cd toxicity on plant cell membrane permeability and efficiency.The average of BCF in plants for initial Cd concentrations of 1, 2, 4 and 6 mg l-1 were 384.4, 707.9, 66.5 and 75.0respectively. High reduction ofBCF amounts with increasing the initial concentration of 2to 4 and 6mg l-1, maybe caused by cadmium physiological adverse effects on plants. The averages of uptake index in plants were 1.26, 2.95, 2.24 and 3.92 mg for initial Cd concentrations of 1, 2, 4 and 6 mg l-1respectively. The results showed a reduction between 2 and 4 mg l-1concentrations that probablycaused by Cd toxicity disruption on plants uptake mechanism and growth. Moreover, the increase of plants uptake index in initial concentration of 6 mg l-1 could be explain by partial losing of the selective permeability of the plants cell membrane. The maximum (3.60 g/day) and minimum (1.62 g/day) of biomass production related to pollutant concentrations of 0 and 6 mg l-1 respectively, and it shows a greatefect of the Cd on C. demersum L.growth.
Conclusion: The plant accumulated cadmium efficiently, and the remediation efficiency was near to 82%. However, the pollutant removal was not complete in a short time.In total, phytoremediation of cadmium and other pollutants from wastewater or other aqueoussolutions by Ceratophyllumdemersum, as a native aquatic plant of most of Iran’s rivers, could be anefficient and appropriatemethod.
F. Nooralivand; A. Farrokhian Firouzi; A. Kiasat; M. Chorom; A. Akbar Babaei
Abstract
Introduction: During the recent decades, the use of N fertilizers has undeniable development regardless of their effects on the soil and environment. Increasing nitrate ion concentration in soil solution and then, leaching it into groundwater causes increase nitrate concentration in the water and raise ...
Read More
Introduction: During the recent decades, the use of N fertilizers has undeniable development regardless of their effects on the soil and environment. Increasing nitrate ion concentration in soil solution and then, leaching it into groundwater causes increase nitrate concentration in the water and raise the risk suffering from the people to some diseases. World health organization recommended maximum concentration level for nitrate and nitrite in the drinking water 50 and 3 mg/l, respectively. There are different technologies for the removal of nitrate ions from aqueous solution. The conventional methods are ion exchange, biological denitrification, reverse osmosis and chemical reduction. Using nanoscale Fe0 particles compared to other methods of nitrate omission was preferred because of; its high surface area, more reactive, lower cost and higher efficiency. More studies on the reduction of nitrate by zero-valent iron nanoparticles have been in aqueous solutions or in the soil in batch scale. Nanoparticles surface modified with poly-electrolytes, surfactants and polymers cause colloidal stability of the particles against the forces of attraction between particles and increases nanoparticle transport in porous media. The objectives of this study were to synthesize carboxymethyl cellulose stabilized zero-valent iron nanoparticles and consideration of their application for nitrate removal from sandy soil.
Materials and Methods: The nanoparticles were synthesized in a lab using borohydride reduction method and their morphological characteristics were examined via scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier Transmission Infrared Spectroscopy (FTIR). Experiments were conducted on packed sand column (40 cm length and 2.5 cm inner diameter) under conditions of different nanoparticle concentration (1, 2, and 3 g1-1)and high initial NO3- concentration (150, 250, and 350 mgl-1). Homogeneous soil column was filled with the wet packed method. CMC-NZVI suspensions of nanoparticle in aqueous solution (0.01 M CaCl2 and 0.001MKCl) were pumped into the sand column during the injection of nitrate solution. During transport experiment, the flask containing CMC-ZVIN suspension was sonicated using a 50 KH ultrasonicator (DSA100-SK2) to prevent particle agglomeration and ensure homogeneity of the suspensions. In these experiments pore water velocity was 0.16 mms-1. Nitrate and Nitrite concentrations in the samples were measured using UV-VIS.HACH DR 5000 spectrophotometer at wavelengths 220 and 530nm, respectively, and ammonium concentration was measured by Kjeldahl method. All chemicals used in this research were of chemical grades and all solutions were prepared using deionized water (DI).
Results and Discussion: Effect of nanoparticles and nitrate concentration on nitrate reduction by stabilized nanoparticle in sand column was investigated. The Results of study indicating at the first of reaction in both cases rate and amount of nitrate reduction was increased gradually. But over time, due to saturation capacity of nanoparticles at higher concentrations of nitrate, reduction speed and amount of reduction was constant approximately. The result showed that increasing dosage of nanoparticles and decreasing the influent nitrate concentration would increase percentage of nitrate reduction. Maximum percentage of reduction (82.56%) were observed at nanoparticles concentration=3 gl-1 and high initial nitrate concentration=150 mgl-1 and minimum percentage of reduction (63.94%) were observed at nanoparticles concentration=1 gl-1 and high initial nitrate concentration=150 mgl-1. After the end of experiment time, amount of observed ammonium and nitrite was a few in the drainage water of sand column. During the reaction nitrate reduction by nano-particles, H + was used and OH- was produced therefore through reaction, environment pH increased continuously. In conditions of alkaline, ammonium release in the form of N2. Therefore reduction of the amount of ammonium may due to high pH of environment reaction or fixation of ammonium in the surface colloidal of particles in porous medium. Nitrite is an intermediate product and due to the reaction conditions can be converted to ammonia or nitrogen gas. The final product of reduction would be nitrogen gas, and produced nitrite and ammonium was less than 2%.
Conclusion: The results indicate that, in all experiments (effect of nanoparticle and nitrate concentration on nitrate reduction), amount of observed ammonium and nitrite was a few in the drainage water of sand column and most of the nitrate converted to nitrogen gas. Since maximum concentration level of ammonium in drinking water is 50 times less than nitrate concentration, nitrogen gas is an ideal product in water treatment process. Carboxymethyl cellulose prevents agglomeration ZVI nanoparticles and enhanced the reactivity and transport of nanoparticle in the porous media. The findings of this research demonstrated that carboxymethyl cellulose-stabilized zero-valent iron nanoparticles have a high potential for reduction of nitrate in aqueous solutions and porous media. Therefore, it can be used as an effective method for removing nitrate from water.
Abstract
Biofertilizers can be used as complementary in sustainable agriculture. The main target of this study was effects of nitrogen and phosphorus fertilizers and chemical fertilizers on wheat yield and yield components in two soil types. Experimental design as the factorial formed completely randomized design ...
Read More
Biofertilizers can be used as complementary in sustainable agriculture. The main target of this study was effects of nitrogen and phosphorus fertilizers and chemical fertilizers on wheat yield and yield components in two soil types. Experimental design as the factorial formed completely randomized design with three replications was executed. Experiment Factors included two soil types (sandy loam and clay loam) and 9 fertilizer treatments. For the experiment implementation used 100 gram per hectare of Nitrokara (Azorhizobium caulinodans) and Barvar 3 phosphorus (Pseudomonas putida, Strain P13, Pantoea agglomerans, Strain P5 and Pseudomonas putida, Strain MC1) biofertilizers in single and combined forms by method of seed inoculation. The results showed positive effects of clay loam type and inoculation of two biofertilizer types especially in the presence of 50% of chemical fertilizers on shoot dry weight, root dry weight, number of grains per spike, 1000 grain weight and wheat grain yield. The results showed 100% chemical fertilizer and phosphorus biofertilizer in combination with 50 % of chemical fertilizer treatments showed the highest effect in most characteristics and control treatment showed the lowest effect in this characteristics. Nitrokara biofertilizer in combination with 50% of chemical fertilizer had the maximum 1000 grain weight. Phosphorus biofertilizer in combination with 50% of chemical fertilizer on wheat yield and yield components showed a better effect than Nitrokara biofertilizer.The results of this research showed by combining biological and chemical fertilizers can reduce consumption of chemical fertilizers.
V. Sarvi Moghanlo; Mostafa Chorom; M. Falah; H. Motamedy
Abstract
Due to widespread distribution, hydrocarbon toxicity and mutagencity, PAHs are listed as hazardous pollutants, and remediation of soils contaminated with PAHs is a major challenge. The use of degrading microorganisms and plants for bioremediation of PAHs-contaminated environments seems to be a viable ...
Read More
Due to widespread distribution, hydrocarbon toxicity and mutagencity, PAHs are listed as hazardous pollutants, and remediation of soils contaminated with PAHs is a major challenge. The use of degrading microorganisms and plants for bioremediation of PAHs-contaminated environments seems to be a viable technology for restoration of polluted sites. The purpose of this research was investigation the effect of mycorrhiza and degrading bacteria in increasing pytoremediation. For this purpose, the soil deliberately contaminated with crude oil in 1 and 2 wt% rate and four treatments: plant multiflorum (T1), plant multiflorum with mycorrhiza inoculation (T2), plant multiflorum with oil degrading bacteria inoculation (T3), plant multiflorum with mycorrhiza and oil degrading bacteria inoculation (T4) were employed for bioremediation of oil contaminated soil. The study results showed that with increasing the level of pollution, shoots and roots yield was decreased. The percentage of AM colonization in mycorrhizal treatments did not significantly reduce the yield. Most importantly, degradation of oil components was significantly enhanced by the addition of oil-degrading microorganisms, compared to remediation of growing plants alone at both level of pollution. The highest oil degradation (85%) was observed with AMF + oil degrading bacteria in soil with pollution level of 2%., GC results indicated that all normal paraffin and isoperopanoids i.e. Phytane and Pristane decreased from 40 to 80 percent in treatments with oil-degrading microorganisms.
M. Chorom; A. Alizadeh
Abstract
Abstract
The plants which can be used to clean up the soil of heavy metals contamination are named phytoremedation. Phytoremediation has received increasing attention because of its low environmental impact and cost-effectiveness. But, it is slowly process and needs long time. In such reson, chelating ...
Read More
Abstract
The plants which can be used to clean up the soil of heavy metals contamination are named phytoremedation. Phytoremediation has received increasing attention because of its low environmental impact and cost-effectiveness. But, it is slowly process and needs long time. In such reson, chelating agents have been proposed to improve the efficiency of phytoextraction by increasing solubility of target metals from soil. Synthetic chelates and low molecular weight organic acids are the most common chemical amendments that have been used in chemically assisted phytoextraction of metals from soils. The objective of this work was comparison of EDTA and sugarcane by product compost in enhancing phytoextraction of Cd, Pb, and Ni by canola in an artificially contaminated soil. Two levels of contamination (800 and 1600 ppm) were performed. The soil were placed in dark condition for 2 weeks and compost of sugarcan were applied in two levels (20 and 50 ton per hectar). A number of 5 canola seeds with grower power 95% germination were cultivated. Two weeks after cultivation, the treatments included EDTA in numbers of (0,10,20mmol /kg soil) with irrigated water were added to the pots. Eight weeks after cultivating the plants cut as well as the analysis of the soil and the plant in the laboratory was made. All treatments significantly increased the concentrations of Cd, Pb and Ni in the shoots of plants compared with the control. Therefore, the influence of EDTA and compost were observed more powerful for enhanced phytoextraction of the heavy metals. The effectiveness of EDTA and compost to stimulating the accumulation of Cd, Pb and Ni in shoots plants were (4.3 and 4.1), (4 and 4.2) and (2.8, and 2.9) times more respectively, than the control. Also, the results of this study indicated that all treatments were superior in terms of solubilizing soil Pb, Cd and Ni for root uptake and translocation into shoots Canola but, in different levels.
Key words: Phytoremediation, EDTA, Compost of sugarcane,Uptake index, Heavy metals