Akbar Karimi; Habib Khodaverdiloo; MirHasan Rasouli Sadaghiani
Abstract
Introduction: Recently, due to enhancement of industrialization, urbanization and disposal of wastes, fertilizers and pesticides the concentration of heavy metals (HMs)in agricultural soil has increased. Heavy metals are serious threat for environment due to their hazardous effects. Lead (Pb) is one ...
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Introduction: Recently, due to enhancement of industrialization, urbanization and disposal of wastes, fertilizers and pesticides the concentration of heavy metals (HMs)in agricultural soil has increased. Heavy metals are serious threat for environment due to their hazardous effects. Lead (Pb) is one of the toxic heavy metal that threats the health of plants, living organisms and human. Excessive Pb concentrations in agricultural soils result in decreasing the soil fertility and health which affects the plant growth and leads to decrease in plant growth. Plants simultaneously exposed to Pb suffer morphological, biochemical and physiological injury. Pb adversely affect plant absorption of essential elements, chlorophyll biosynthesis and shoot and root growth. Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) are known to enhance nutrient uptake and improvement of plant growth and tolerance in heavy metal contaminated soils through different mechanisms including producing low molecular weight organic acids, siderophore, antibiotics and hormones. The objective of this study was to evaluate the effect of AMF and PGPR on yield, leaf relative water content (RWC), some biochemical properties and uptake of Pb, Fe and Zn by Hyoscyamus (Hyoscyamus niger L.) under soil Pb contamination.
Materials and Methods: This study was carried out in greenhouse condition as a factorial experiment based on a randomized complete block design with two factors including Pb concentration (in four levels) and microbial treatment (in three levels including arbuscular mycorrhizal fungi, plant growth-promoting rhizobacteria and control) and in three replications. Consequently, a soil was selected and spiked uniformly with concentrations of Pb (0, 250, 500 and 1000 mg Pb kg-1 soil). The contaminated soil was then sterilized and inoculated with the selected species of arbuscular mycorrhizal fungi (a mixture of Glomus species including G. intraradices, G. mosseae and G. fasciculatum) or plant growth-promoting rhizobacteria (a mixture of Pseudomonas species includeing P. putida, P. fluorescens, and P. aeruginosa). Seeds of Hyoscyamus niger L. plant were grown in pots containing the Pb spiked soil. At the end of growth period shoot length, dry weights of root and shoot, Fe, Zn and Pb concentration in shoot, and some biochemical and physiological properties of plant including relative water content (RWC) chlorophyll a, b and total chlorophyll, carotenoids, proline and soluble sugars, were measured.
Results and Discussion: Results indicated that with increasing soil Pb concentration, dry weights of root and shoot, shoot length, photosynthetic pigments contents (chlorophyll a, chlorophyll b, total chlorophyll and carotenoids), shoot Fe and Zn concentration decreased, while proline and soluble sugars contents and the shoot Pb concentration increased. With increasing of soil Pb concentration, relative water content decreased, however, this reduction in concentration of 1000 mg Pb kg-1 soil was not significant (P > 0.05) in compared with concentration of 1000 mg Pb kg-1 soil. Amounts of all measured properties in AMF and PGPR treatments were higher than that control treatment. The highest values of shoot weight and root weight, were observed in plants that inoculated with AMF. The lowest shoot weight was recorded in non-inoculated plants that were grown under 1000 mg Pb kg-1 soil concentration. In this study Arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria inoculation led to a significant increase (P≤0.05) in shoot length (12.9 -71.1%), shoot dry weight (11.5 – 81%), root dry weight (18.4 – 60.6%), chlorophyll (8.5 – 36.5%) and carotenoid (11.5 – 40.0%) pigments, proline (55 – 115.7%), soluble sugars (17.6 – 72.2%) and shoot Fe (9.5 – 57.2%) and Zn (25.0 – 165.5%) concentration in shoot at different levels of soil Pb. The highest and lowest amounts of shoot Fe, Zn and Pb concentration observed in AMF and control treatments respectively. Plant growth promoting rhizobacteria were more effective than arbuscular mycorrhizal fungi in shoot Fe, Zn and Pb concentration, while the mean of shoot length and shoot and root dry weight was higher in plants that inoculated with AMF compared to ones inoculated with PGPR. In general, there were not significant (P ≤ 0.05) differences in amounts of chlorophyll (chlorophyll a, b and chlorophyll a+b) and carotenoids pigments, proline and soluble sugars between AMF and PGPR treatments.
Conclusion: It could be concluded that microbial inoculation (mixture of AMF and PGPR species) with improvement of plant biochemical properties results in improved Hyoscyamus niger L. yield and increased tolerance to Pb toxicity. Thus, the use of microbial inoculation (mixture of AMF and PGPR species) inoculation might be suggested for enhancement of plant tolerance in Pb contaminated soils.
F. Afrasiabi; H. Khodaverdiloo; F. Asadzadeh
Abstract
Introduction Particle size distribution (PSD) is one of the most fundamental features of soil physics that is widely used as the most common input for predicting several key soil attributes. The mathematically representing the PSD provides several benefits to soil mechanics, physics, and hydrodynamics ...
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Introduction Particle size distribution (PSD) is one of the most fundamental features of soil physics that is widely used as the most common input for predicting several key soil attributes. The mathematically representing the PSD provides several benefits to soil mechanics, physics, and hydrodynamics as well as helps to convert PSD data of various particle size classification systems to the desired one. Consequently, the correct and consistent descriptions of soil PSD by using mathematical functions is necessary.
The PSD models have often been evaluated in terms of their general performance for predicting the entire PSD curve. However, a given model may be feasible and globally perform well to generate the whole PSD curve but locally may fail to predict some specific points on the curve. To our knowledge, as well as, PSD models have not been widely tested for salt-affected soils with different levels of salinity/sodicity.
The aim of this study was to determine the error structure of several more accurate PSD models in selected soil samples with different levels of salinity and sodicity.
Materials and Methods Twenty four locations neighboring the western edge of threatened hypersaline Lake Urmia were sampled in this study. The locations were selected considering the available soil maps so that soils with wide range of salinity/sodicity were sampled. Selected physical and chemical properties of the soil samples were determined by standard methods. The performance of six PSD models including Modified Logistic Growth (MLG), Fredlund type models with three (Fred-4p) and four (Fred-3p) parameters, Anderson (AD), ONL, and Weibull (Wei), which have been reported as the most accurate PSD models by previous studies, was evaluated by using different efficiency criteria that offer various performances depending on the range of particle sizes.
An iterative nonlinear optimization procedure was used to fit the observed cumulative PSD data of the soils to the PSD models. Since every statistical criterion evaluates a part and some (and not all) aspects of the correspondence between measured and predicted values, we suggest that an effective assessment of model performance should include a suitable combination of criteria. Furthermore, dependence of the models performance to the range of soil particle sizes was examined.
Results and Discussion The soils differed widely in their EC (range = 85dS/m and CV = 159%), ESP (range = 67 % and CV = 71 %), and PSD (CV of clay and silt particles, 48 and 55 %, respectively). Soil textural class of the soils was differed widely from sandy loam to clay. All the soils were calcareous and alkaline.
The results showed that according to the efficiency criteria, including R2 (coefficient of determination), RMSE (Root Mean Square Error) and Er (Relative Error), all of the models have high efficiency, so that, the lowest average value of R2 in models was 0.992 and the maximum value of RMSE and Er was 0.028 and 0.045, respectively.
Prediction error of the models was dependent on the diameter for which we predict the cumulative fraction and decreases with increasing of the soil particles diameter. The performance of the models showed a significant quadratic polynomial relationship with sand content of the samples, so that, the studied models had the lowest performance in soils containing 30 to 45 percent sand.
The point-to-point error structure of model represents a decrease in systematic error in estimating coarse soil particles, while the models over-estimated the relative frequency of the fine soil particles. In addition, the values of relative error were also lower for coarse particles of soil, so that, the Wei model (for example) had the lowest Er value for 100 to 500 μm diameter soil particles. The relatively high correlations between parameters of Fred-3p, MLG and ONL models show insights to reduce the number of their parameters.
Furthermore, parameters a and c of MLG model, parameters μ and α of ONL model and parameter α and m of Fred-3p model had a statistically significant correlations. The relatively high correlations between parameters of the PSD models show insights to reduce the number of their parameters which increases their applicability.
Conclusion The studied models generally performed well to predict the whole PSD curve, but their performance was particle size dependent. This implies that, one should consider the range of sizes of soil particles for which the model are used. A model might be accurate enough for predicting some ranges of particle diameter or the whole PSD, but not for particular range of particle sizes. Using such models might lead to large errors in predicting the specific PSD range of interest.
MirHassan Rasouli-Sadaghiani; Habib Khodaverdiloo; Mohsen Barin; Solmaz Kazemalilou
Abstract
Introduction: Heavy metals (HMs) are serious threat for environment due to their dangerous effects. These metals as contaminants that can be accumulated in soil and after absorption by plants, finally will be found in food chains. Cadmium (Cd) is one of the dangerous HMs that threats the health of plants, ...
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Introduction: Heavy metals (HMs) are serious threat for environment due to their dangerous effects. These metals as contaminants that can be accumulated in soil and after absorption by plants, finally will be found in food chains. Cadmium (Cd) is one of the dangerous HMs that threats the health of plants, living organisms and human. Physicochemical remediation methods may cause large changes in different characteristics of soils . Recently environmental-friendly strategies including phytoremediation have been emphasized by researchers. Phytoremediation that refers to the use of plants and their assistance with microorganisms for remediation of contaminated soils is an effective and low cost method for reclamation of heavy metals polluted soils. The most important limitation of phytoremediation is low availability of heavy metals and sensitivity of plants to contamination. There are evidences that soil microbes can help to overcome these limitations through several ways. Plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) are known to enhance plant growth and survival in heavy metal contaminated soils through different mechanisms including producing promoting metabolites, auxin, siderophore and antibiotics. In this study the role of some strains of PGPR (a mixture of Pseudomonas species including P. putida, P. fluorescens, and P. aeruginosa) and AMF (a mixture of Glomus species including G. intraradices, G. mosseae and G. fasciculatum), on uptake and accumulation of Cd, Fe, Zn and Cu as well as some physiological properties of Onopordon (Onopordon acanthium L) were evaluated.
Materials and Methods:This study was carried out under greenhouse condition as a factorial experiment based on a randomized complete block design with two factors including Cd concentration (four levels) and microbial treatment (three levels) in three replications. Consequently, a soil was selected and spiked uniformly with different concentrations of Cd (0, 10, 30 and 100 mg Cd kg-1 soil) at greenhouse of agricultural college in Urmia University. The contaminated soils were then sterilized and subsequently inoculated with arbuscular mycorrhizal fungi (a mixture of Glomose species including G. intraradices, G. mosseae and G. fasciculatum) and plant growth promoting rhizobacteria (a mixture of Pseudomonas species includeing P. putida, P. fluorescens, and P. aeruginosa). The seeds of Onopordon plants were grown in 2.5 kilogram pots under greenhouse condition. At the end of growing season the shoot dry weight, Cd, Fe, Zn and Cu concentration and element contents and some of physiological parameters of plant as well as microbial properties were analyzed. Furthermore, the effect of soil Pb level on population, activity and efficiency of the inoculated microbes was studied.
Results and Discussion: Significant difference was observed for plants’ dry weights. At different Cd levels, the yield of inoculated plants was higher than that of control plants. Furthermore, at elevated Cd concentration, plant height, biomass, relative yield, chlorophyll a, b, carotenoids, relative water content (RWC) decreased significantly (P < 0.05), however, plants inoculated with plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi showed considerable amount of dry matter, chlorophyll a, b as well as RWC. Mycorrizal and bacterial inoculation and Cd treatment also had significant effect on leaf photosynthetic pigments concentration and plant relative water content. In general, concentrations of photosynthetic pigments and RWC were higher in inoculated plants at every level of soil Cd. The microbial inoculation effectively decreased the inhibitory effects of Cd on plant growth. Shoot yield of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria plants increased by 2.7 and 2.1 times as well as microbial respiration increased by 2.17 and 2.01 times compared to control treatment. The results showed inoculated plant absorbed more Cd than non-inoculated plants. Plant growth promoting rhizobacteria were more effective than arbuscular mycorrhizal fungi inoculation in shoot Cd concentration. Cd contamination reduced soil microbial population and basal respiration. Results showed that with increasing soil Cd concentration shoot Fe, Zn and Cu concentrations significantly decreased. Root colonization rates decreased significantly with 10 mg kg-1 Cd addition for AMF treatments, and drastically with 100 mg kg-1 Cd added. Plant roots in the control and PGPR treatment were not colonized.
Conclusion: It is concluded that plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi inoculation could be sustained and promoted plant growth in phytoremediation processes. Therefore, under Cd contamination it can be use PGPR and AMF as growth promoters and finally enhance phytoremediation efficiency.
S. Mirzaee; S. Ghorbani Dashtaki; H. Khodaverdiloo
Abstract
Introduction: The infiltration process is one of the most important components of the hydrologic cycle. Quantifying the infiltration water into soil is of great importance in watershed management. Prediction of flooding, erosion and pollutant transport all depends on the rate of runoff which is directly ...
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Introduction: The infiltration process is one of the most important components of the hydrologic cycle. Quantifying the infiltration water into soil is of great importance in watershed management. Prediction of flooding, erosion and pollutant transport all depends on the rate of runoff which is directly affected by the rate of infiltration. Quantification of infiltration water into soil is also necessary to determine the availability of water for crop growth and to estimate the amount of additional water needed for irrigation. Thus, an accurate model is required to estimate infiltration of water into soil. The ability of physical and empirical models in simulation of soil processes is commonly measured through comparisons of simulated and observed values. For these reasons, a large variety of indices have been proposed and used over the years in comparison of infiltration water into soil models. Among the proposed indices, some are absolute criteria such as the widely used root mean square error (RMSE), while others are relative criteria (i.e. normalized) such as the Nash and Sutcliffe (1970) efficiency criterion (NSE). Selecting and using appropriate statistical criteria to evaluate and interpretation of the results for infiltration water into soil models is essential because each of the used criteria focus on specific types of errors. Also, descriptions of various goodness of fit indices or indicators including their advantages and shortcomings, and rigorous discussions on the suitability of each index are very important. The objective of this study is to compare the goodness of different statistical criteria to evaluate infiltration of water into soil models. Comparison techniques were considered to define the best models: coefficient of determination (R2), root mean square error (RMSE), efficiency criteria (NSEI) and modified forms (such as NSEjI, NSESQRTI, NSElnI and NSEiI). Comparatively little work has been carried out on the meaning and interpretation of efficiency criteria (NSEI) and its modified forms used to evaluate the models.
Materials and Methods: The collection data of 145 point-data of measured infiltration of water into soil were used. The infiltration data were obtained by the Double Rings method in different soils of Iran having a wide range of soil characteristics. The study areas were located in Zanjan, Fars, Ardebil, Bushehr and Isfahan provinces. The soils of these regions are classified as Mollisols, Aridisols, Inceptisols and Entisols soil taxonomy orders. The land use of the study area consisted of wheat, barley, pasture and fallow land.The parameters of the models (i.e. Philip (18), Green and Ampt (3), SCS (23), Kostiakov (6), Horton (5), and Kostiakov and Lewis (11) models) were determined, using the least square optimization method. All models were fitted to experimental infiltration data using an iterative nonlinear regression procedure, which finds the values of the fitting parameters that give the best fit between the model and the data. The fitting process was performed using the MatLab 7.7.0 (R2008b) Software Package. Then, the ability of infiltration of water into soil models with the mean of coefficient of determination (R2), root mean square error (RMSE), efficiency criteria(NSEI) and modified forms (such as NSEjI, NSESQRTI,NSElnI and NSEiI) were determined and goodness of criteria was compared for the selection of the best model.
Results and Discussion: The results showed the mean of RMSE for all soils cannot always be a suitable index for the evaluation of infiltration of water into soil models. A more valid comparison withNSEI, NSEjI, NSESQRTI, NSElnI indices indicated that these indices also cannot apparently distinguish among the infiltration models for the estimation of cumulative infiltration. These indices are sensitive to the large amount of data. The NSEiI index with giving more weight to infiltration data in shorter times was selected as the most appropriate index for comparing models. According to the NSEiI index, Kostiakov and Lewis, Kostiakov, SCS, Philip, Horton, and Green and Ampt models were the best models in approximately 72.42, 44.83, 26.9, 53.11, 11.73 and 1.0 percent of soils, respectively.
Conclusion: The results of this study indicated that the ability of modified forms of NSE indices in evaluation of infiltration of water into soil models depend on the influence of models from infiltration data values in different time series. This encourages us to be cautious on the application and interpretation of statistical criteria when evaluating the models.
Keywords: Error, Statistical criteria, Infiltration water into soil
A. Rashid Shomali; H. Khodaverdiloo; A. Samadi
Abstract
However some of heavy metals such as Zn, are essential for plant growth, their elevated concentrations have toxic effects and may inhibit plant growth. In this study, plant tolerance and Zn uptake and accumulation potential of some weed plant species from Western Azerbaijan region were studied in a soil ...
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However some of heavy metals such as Zn, are essential for plant growth, their elevated concentrations have toxic effects and may inhibit plant growth. In this study, plant tolerance and Zn uptake and accumulation potential of some weed plant species from Western Azerbaijan region were studied in a soil spiked with 0, 1000, 3000 and 6000 mgZn kgsoil-1. Seed of heliotrope (Heliotropium europaeum), Lambsquarter (Chenopodium album), Orach (Atriplex sp.), Amaranth (Amaranthus retroflexus), Millet (Pennisetum glaucum), Alfalfa (Medicago sativa) and purslane (Portulaca oleracea) were grown in pots containing the Zn contaminated soil. At the end of growing season, plants relative yield (RY%), plants shoot metal concentration, metal bioconcentration factor (BCFZn) and plants metal extraction (MEZn( from soil were measured. Results showed that with an exception for Lambsquarter and purslane, plants biomass decreased significantly (P≤ 0.05) with increasing Zn concentration in soil, especially, in higher soil Zn contaminations. Compared with other plants studied, Amaranth had the highest BCFZn and MEZn in blank and 6000 mgZn kgsoil-1 treatments. Amaranth, Lambsquarter and Orach with a relatively high biomass (750 to 960g dry matter bush-1 in native condithios) and middle rate of Zn uptake might be effective in remediation of Zn from contaminated soils
B. Rajabi; H. Khodaverdiloo; A. Samadi; M.H. Rasouli Sadaghiani
Abstract
Abstract
The availability of heavy metals in the soil is related to their partitioning between solution and solid phases and expressed by sorption isotherm. Twenty surface soil samples (0-30 cm) belonging to five soil subgroups were taken from agricultural regions of Western Azerbaijan province. The ...
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Abstract
The availability of heavy metals in the soil is related to their partitioning between solution and solid phases and expressed by sorption isotherm. Twenty surface soil samples (0-30 cm) belonging to five soil subgroups were taken from agricultural regions of Western Azerbaijan province. The sorption isotherms of Pb were determined by equlibrating the soil with solutions containing 0, 100, 300, 500, 700, 900, 1100 and 1300 mg Pb L-1 from Pb-nitrate source in 0.01 M NaNO3 as background electrolyte. Illite was the dominant clay mineral in Typic Calcixerepts (TC), Typic Haploxerepts (TH) and Typic Endoaquepts (TE) whereas in Vertic Calcixerepts (VC) and Vertic Endoaquepts (VE) the clay mineralogy was dominated by smectite. Active and equivalent calcium carbonate and clay contents ranged from 4.3 to 7.8%, 6.2 to 16% and 31 to 45%, respectively. The linaer, Langmuir and Freundlich isotherm equations were fitted to the experimental data of Pb sorption and desorption. Both the Freundlich (0.98< R2
R. Hamzenejad Taghlidabad; H. Khodaverdiloo; Sh. Manafi; S. Rezapour
Abstract
Abstract
Nowadays, environmental pollution by heavy metals is one of the most serious threats of the world which needs effective remediation actions. The aim of this study was to investigate the potential use of Atriplex [Atriplex verucifera], Salicornia [Salicornia europaea] and Chenopodium Album in ...
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Abstract
Nowadays, environmental pollution by heavy metals is one of the most serious threats of the world which needs effective remediation actions. The aim of this study was to investigate the potential use of Atriplex [Atriplex verucifera], Salicornia [Salicornia europaea] and Chenopodium Album in simultaneous uptake and accumulation of Na and Cd or Pb in two calcareous soils with different properties. Two soils, including a saline-sodic-calcareous (S1) and a calcareous (S2) soil, were selected. Different concentrations of Pb (0, 250, 500 and 1000 mg Pb kg-1 soil) and Cd (0, 10, 30 and 100 mg Cd kg-1) were then added to the soils. . The contaminated soils were incubated under a wetting-drying moisture regime for nearly seven months. The plants seeds were grown in pots containing different treatments of polluted soils and in control treatment (no Cd and Pb contaminations). The plant yields and concentrations of Pb, Cd and Na in the soil and plant samples were measured. Results showed that relative yield of Salicornia was more in soil S1, whereas those of Atriplex and Chenopodium Album were more in soil S2. In saline- sodic soil, the values of Na bioconcentration factor (BCENa) in control treatment were 67, 202 and 57 for Atriplex, Salicornia and chenopodium album respectively. The high value of BCENa in Salicornia revealed the ability of this plant in absorption and accumulation of Na from soil. A considerable accumulation of soil Cd by Salicornia and Pb accumulation by Atriplex and Salicornia was observed under unsuitable conditions of the saline-sodic soil, whereas, Atriplex and Chenopodium had high capability for Cd in the soil S2. These results revealed that these plants could be used for remediation of Pb and Cd contaminated soils. In this study, Salicornia with lower rate of yield reduction had the highest tolerance to Cd-stress and it seems that one can use this plant for phytiremediation of Cd and Pb from saline- sodic soil even in high concentrations of Cd and Pb.
Keywords: Bioaccumulation, Sodium (Na), Lead (Pb), Cadmium (Cd), Halophyte plants
