Research Article
S.A. Haghayeghi; A. Alizadeh
Abstract
Permissible working hours of agricultural wells in the Neyshabour plain was determined equal 4120 hours by regional water authority of Khorasan-e-Razavi. This research was conducted to introduce method of working hours of agricultural wells in the Khorasan-e-Razavi province (case study of Neyshabour ...
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Permissible working hours of agricultural wells in the Neyshabour plain was determined equal 4120 hours by regional water authority of Khorasan-e-Razavi. This research was conducted to introduce method of working hours of agricultural wells in the Khorasan-e-Razavi province (case study of Neyshabour plain) and analyse effective parameters on working time of wells. For this purpose, the area of agronomy and horticulture crops was obtained for the years of 2001 to 2010. Water requirement of these crops was extracted from the water national document. Working hours of wells for every months would be calculated by deviding gross irrigation requirement to average hydromodul of three maximum months. The calculations to assess the effect of sowing pattern was done separately in two phases, for all crops pattern and for major crops pattern. In the thirth and forth phases, the effect of annual variation of water requirement and irrigation hydromodul were assessed on the working hours of Neyshabour plain wells. The results showed that instead of using all crops pattern, it is possible to use just major crops in calculating of working hours of wells. Annual variation of sowing pattern and water requirement in the Neyshabour plain have significant effect (95% confidence) on working hours of wells. By suppose the constant area under crops in the Neyshabour plain, adjust in calculating of working hours of wells was done using measured hydromodul in the region. In adjusted method, the annual working hours showed increase averagely 440 (11%) hours in compare to permissible working hours of Neyshabour plain (4120 hours). This variety in working hours of wells cause to be near to existence and realy conditions of the Neyshabour plain. In an agronomy year, it is possible to have an acceptable forcasting for working hours of regional wells by determining the sowing area of wheat and barley.
Research Article
B. Rostamian; E. Maroufpoor; N. Azarboo; F. Farzankia
Abstract
Correct understanding of the factors affecting the rate of evaporation l and wind draft losses on sprinkler irrigation systems is important in order to provide guidelines for the development and utilization of water resources. This study was performed to identify the factors affecting the rate of evaporation ...
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Correct understanding of the factors affecting the rate of evaporation l and wind draft losses on sprinkler irrigation systems is important in order to provide guidelines for the development and utilization of water resources. This study was performed to identify the factors affecting the rate of evaporation and wind draft losses and also equations presents for estimating of evaporation and wind draft losses on the fixed head sprinkler irrigation systems, under various conditions of hydraulic and atmospheric. In this study sprinklers of ZK30, ZM22 and AMBO was used. The tests were carried out at the University of Kurdistan research farm located in the village of Doshan with single sprinkler method Accordance with the ISO 7749-1 and ISIRI 8995-3 standards. Evaporation and wind draft Losses were measured at different applied pressures under various conditions of atmospheric. The results showed that parameters of vapor pressure deficit and temperatures had the highest correlation with evaporation and wind draft losses in all three types of sprinklers, and this correlation is significant at the 1% probability level. Also results showed that the correlation between wind velocity and losses is in sprinklers of ZM22 and ZK30 significant at the 1% and 5% probability level respectively and in the sprinkler AMBO is no significant correlation. In overall evaporation and wind draft losses increase to 9.4 percent by increasing of 1 meter per second of wind velocity.
Research Article
H. Ghamarnia; F. Mousabeygi
Abstract
For optimal use of water resources determination of crop coefficients and water requirement for each region is necessary.The present study was conducted to determine the values of water requirement and crop coefficients of Peppermint (Mentha piperita L.) in a semi arid climate. For this purpose, eight ...
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For optimal use of water resources determination of crop coefficients and water requirement for each region is necessary.The present study was conducted to determine the values of water requirement and crop coefficients of Peppermint (Mentha piperita L.) in a semi arid climate. For this purpose, eight water balance drainable lysimeters were used. For those reasons two lysimeters was used for grass and bare soil evapotranspiration estimation. Also in six other lysimeters, peppermint in two groups A (Plant growth was continued until the end of flowering.) and B (plant harvested three times, after reaching a height of 10-12 cm) was planted. Finally the average water requirement of Peppermint in two lysimeters groups A and B were determined as 664.4 and 566.4 mm respectively. Single and base crop coefficients for lysimeters in group A, for the initial, development and middle stages of peppermint growth were determined as, 0.69 ، 1.03 ، 1.27 and 0.29، 0.86، 1.17 respectively . Also the average of single crop coefficients on first, second and third harvests for lysimeters in group B was determined as 0.84 ، 0.92 ، 0.96 respectively.
Research Article
J. Dowlati; Gh. Lashkaripour; N. Hafezi Moghadas
Abstract
Zahedan aquifer is located in the northernof Zahedanwatedshed. It is essential to evaluate the quality of groundwater resources due to proving some part of drinking water, agricultural and industrial waters of this city. In order to carry out ground water quality monitoring, and assess the controlling ...
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Zahedan aquifer is located in the northernof Zahedanwatedshed. It is essential to evaluate the quality of groundwater resources due to proving some part of drinking water, agricultural and industrial waters of this city. In order to carry out ground water quality monitoring, and assess the controlling possesses and determine cations and anions sources of the groundwater, 26 wells were sampled and water quality parameters were measured.The results of the analysis showed that almost all of the samples proved very saline and electrical conductivity varied from 1,359 to 12,620μS cm−1. In the Zahedan aquifer, sodium, chloride and sulfate were predominant Cation and Anions respectively, and sodium-chloride Na-Cl( and sodium - sulfate)Na-So4) were dominant types of the groundwater. The factor analysis of samples results indicates that the two natural and human factors controlled about the 83/30% and 74/37% of the quality variations of the groundwater respectively in October and February. The first and major factor related to the natural processes of ion exchange and dissolution had a correlation with positive loadings of EC, Ca2+, Mg2+, Na+, Cl-, K+ and So42- and controls the 65.25% of the quality variations of the ground water in October and the 58.82% in February. The second factor related toCa2+, No3- constituted the18.05% of the quality variations in October and 15.56% in February, and given the urban development and less agricultural development in the aquifer, is dependent on human activities. For the samples collected in October, the saturation indices of calcite, gypsum and dolomite minerals showed saturated condition and calcite and dolomite in February showed saturated condition for more than 60% and 90% of samples and gypsum index revealed under-saturated condition for almost all samples.The unsaturated condition of Zahedan groundwater aquifer is resulted from the insufficient time for retaining water in the aquifer to dissolve the minerals. So42- and No3- Ions in more than 70 percent samples showed unnatural sources (the sewer infiltration).
Research Article
Y. Aminpour; M. Yasi; J. Farhoudi; H. Khalili Shayan
Abstract
The development of an enhanced approach for the use of radial gates as flow measurement structures is important in irrigation networks. In this study, new theoretical relationships were developed to estimate the discharge coefficient (Cd) for a single radial gate with three different sills, at free and ...
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The development of an enhanced approach for the use of radial gates as flow measurement structures is important in irrigation networks. In this study, new theoretical relationships were developed to estimate the discharge coefficient (Cd) for a single radial gate with three different sills, at free and submerged flow conditions. These equations were calibrated and verified by using about 2600 laboratory data from the world-wide literature. Results indicated that the flow rate under the radial gates can be estimated by an error in the order of ±5%. The reliability of the proposed relationships and in particular the scale effects, were tested using 530 field data of radial gates operating on different canal networks. The predictions of the flow rates from the proposed method are shown to be superior compare with the other predictive methods. In the presence of multi radial gates in a given cross section, the total discharge is estimated by an error up to ±30% when using single radial gate relationships. This discrepancy is considered to be mainly due to the influence of different gate openingsand the difference between gate and canal widths. A self-developed correction factor, k, was introduced to account for the dimensionless effective parameters such as the ratio of gate-to-canal width, the geometry of the gates, and the ratios of upstream and downstream depths to the average gates openings. The results are promising the predictive errors of the total flow rates are reduced by ±5% and ±10% for 74% and 94% of the flow data, respectively.
Research Article
T. Asadollahzadeh; M. Mashal; S. Karimzadgan
Abstract
Saturated hydraulic conductivity (Kfs) and sorptive number are the most important hydraulic characteristics effective on soil process. Cased boreholes falling-head permeameter (Philip method) is the one of hydraulic conductivity measurement borehole method. The analysis borehole cased falling-head in ...
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Saturated hydraulic conductivity (Kfs) and sorptive number are the most important hydraulic characteristics effective on soil process. Cased boreholes falling-head permeameter (Philip method) is the one of hydraulic conductivity measurement borehole method. The analysis borehole cased falling-head in unsaturated area promoted and investigated .This method has been investigated by HYDRUS- 2D simulator but in this study is not use experimental data. The purpose of this study precision investigation and determine Reynolds method accuracy by experimental data. Thirty boreholes has been prepared, 12 boreholes with 4 different length and 4 centimeters diameter, 9 boreholes with 3 different length and diameters of 6 and 8 centimeters (3 replications done for each length). A program was written by FORTRAN language for solving the equations presented by Reynolds. Shaghaghi et al determine soil hydraulic conductivity by Guelph method in mentioned area. The results gained by FORTRAN program compared by Shaghaghi et al results. Results showed that the best data drawdown zone for determining Kfs and α* is lower range of data. Considering studies is shown that diameter and length of cased boreholes are not effective on investigation and every length and diameter can be used for solving Reynolds equation. Also the results show that the best gravity factor for precision of estimation is obtained in zero value.
Research Article
Kh. Barati; B. Mostafazadeh-Fard; A. A. Sheikhbahaei
Abstract
The main problem with trickle irrigation is the emitter’s clogging. Using Merus ring is a new method for reducing sedimentation. The effect of Merus ring is based on molecular oscillations of salts in water and the performance of this device is not based on magnetic field. This study was performed ...
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The main problem with trickle irrigation is the emitter’s clogging. Using Merus ring is a new method for reducing sedimentation. The effect of Merus ring is based on molecular oscillations of salts in water and the performance of this device is not based on magnetic field. This study was performed in a field located at Isfahan University of Technology to investigate the effect of Merus ring on emitter’s clogging. Two main treatments of irrigation water, one with Merus ring and another without Merus ring, and three sub-treatments of irrigation water salts were used. The experiment was run for three months and each treatment was irrigated for three hours every day. The results showed that the irrigation water treatment (irrigation with Merus ring and without Merus ring) had significant effect on average emitter’s discharge (qav) at 1% level and on distribution uniformity of emitters (EU) at 5% level. The average emitter’s discharge and distribution uniformity of emitters were higher for the treatment of with Merus ring as compared to the treatment of without Merus ring. For both irrigation water treatments, qav and EU decreased with time during the experiment, but the decrease was higher for the treatment of without using Merus ring. The results showed that the use of Merus ring causes lower emitter clogging and better irrigation performance
Research Article
Z. Parisay; V. Sheikh; M. Ownegh; A. Bahremand
Abstract
Flood is one of the devastating phenomena which every year incurs casualties and property damages. Flood zonation is an efficient technique for flood management. The main goal of this research is flood hazard and risk zonation along a 21 km reach of the Gorganrud river in Bustan dam watershed considering ...
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Flood is one of the devastating phenomena which every year incurs casualties and property damages. Flood zonation is an efficient technique for flood management. The main goal of this research is flood hazard and risk zonation along a 21 km reach of the Gorganrud river in Bustan dam watershed considering two conditions: present landuse condition and scenario planning. To this end a combination of a hydrologic model (the distributed HEC-HMS with the Mod-Clark transform option) and a hydraulic model (HEC-RAS) were used. The required inputs to run the Mod-Clarck module of HEC-HMS are gridded files of river basin, curve number and rainfall with the SHG coordinate system and DSS format. In this research the input files were prepared using the Watershed Modeling System (WMS) at cell size of 200 m. Since the Mod-Clark method requires rainfall data as radar format (NEXRAD), the distributed rainfall mapseries with time intervals of 15 minutes prepared within the PCRaster GIS system were converted to the DSS format using the asc2dss package. also the curve number map was converted to the DSS format using HEC-GeoHMS. Then, these DSS files were substituted with rainfall and curve number maps within the WMS. After calibration and validation, model was run for return periods of 2, 5, 10, 25, 50, 100 and 200 years, in two conditions of current landuse and scenario planning. The simulated peak discharge data, geometric parameters of river and cross section (at 316 locations) data prepared by the HEC-GeoRAS software and roughness coefficients data, were used by the HEC-RAS software to simulate the hydraulic behavior of the river and flood inundation area maps were produced using GIS. The results of the evaluation showed that in addition to the percent error in peak flow, less than 3.2%, the model has a good performance in peak flow simulation, but is not successful in volume estimation. The results of flood zones revealed that from the total area in floodplain with return period of 200 years, 96.94% of the area is exposed to the return period of 25 years floods, and a main part of damages go to the floodplains which are under a return period of 25 years floods.
Research Article
M. Riahi Samani; F. Raiesi
Abstract
The study of soil C dynamics and factors controlling this important soil process in rangeland ecosystems may provide an insight into understanding and evaluating changes in the global C cycle. The primary objective of this study was to quantity the effects of pasture management (i.e., grazing, controlled ...
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The study of soil C dynamics and factors controlling this important soil process in rangeland ecosystems may provide an insight into understanding and evaluating changes in the global C cycle. The primary objective of this study was to quantity the effects of pasture management (i.e., grazing, controlled grazing and ungrazing) on soil C levels and mineralization in three natural rangeland sites of Chaharmahal Va Bakhtiyari province. Three range management regimes including: (a) long-term ungrazed, (b) controlled grazed and (c) free (over) grazed in close vicinity were selected at three sites including SabzKouh (protected from grazing for 18 years), Boroujen (protected from grazing for 23 years) and Sheida (protected from grazing for 2 years). Soil samples were collected from 0-15 cm depth and organic C, total N and C mineralization were measured using standard methods. Results show that SabzKouh and Sheida sites had the highest (14.6 mg g-1) and the lowest (4.80 mg g-1) soil organic C contents, respectively. Soil total N and organic C contents at SabzKouh were significantly higher when compared to other sites, probably due to more rainfall and humid climate. The effect of range management on soil C mineralization was evident at two of the three sites. Results indicate that the exclusion of grazing animals resulted in an increase in soil C mineralization at SabzKouh and Boroujen sites, probably through the addition of plant residues and animal excrements to the soil. However, ungrazed management did not improve plant cover and soil properties in Sheida area, due likely to dry climate conditions, less biomass production and the history of cultivation and agricultural uses. It is, therefore, concluded that the effect of grazing on soil C mineralization depends primarily upon the plant community and climatic conditions and also upon the type of rangeland management and even land use history involved.
Research Article
Gh. Rahimi; A. A. Charkhabi
Abstract
The paddy soils in Lenjan area exposed to pollution owing to uncontrolled discharge of sewage sludge, wastewater and unessential fertilizers. Little information exists on Cadmium (Cd) distribution in paddy soils of Isfahan Province, this study was therefore investigated the spatial variability of cadmium ...
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The paddy soils in Lenjan area exposed to pollution owing to uncontrolled discharge of sewage sludge, wastewater and unessential fertilizers. Little information exists on Cadmium (Cd) distribution in paddy soils of Isfahan Province, this study was therefore investigated the spatial variability of cadmium which is considered as the most toxic metals. 90 soil samples (0-20 cm) were collected from study area. Soil properties such as pH, EC, calcium carbonate equivalent, soil texture, organic matter and cation exchange capacity were measured. The total and available Cd concentrations of soil samples analyzed by atomic absorption spectrophotometer. In addition, estimation of spatial data performed via kriging interpolation method (ordinary and blocky kriging) and by GIS. The total and available concentration of Cd in the study area were averagely 1.747 and 0.073 mgkg-1 respectively, which were much higher than the standard limit and classified in high pollution. Geostatistical analysis result was shown that exponential and spherical models for the total and available Cd concentration were best model, respectively. The most effective range of total and available Cd was 1011 and 1050 meter respectively and correlation ratio was weak in this range. Evaluation of correlation coefficient, MEE and RMSE parameters showed that both methods of kriging for data estimation in comparison with real data had acted in an appropriate manner. The result also showed that human activities such as industrial and urban wastewater entering to the water resources and application of excessive fertilizers had an impact on cadmium concentrations significantly.
Research Article
S. Abdi; reza ghasemi; N.A. Karimian; M. Feizian
Abstract
Sum of exchangeable and solution forms of soil potassium is widely used to determine potassium availability for plants. Reliability of these methods is not enough in soils that contain 2:1 phyllosilicates. Additional to exchangeable potassium, nonexchamgeable potassium also has an important role in plant ...
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Sum of exchangeable and solution forms of soil potassium is widely used to determine potassium availability for plants. Reliability of these methods is not enough in soils that contain 2:1 phyllosilicates. Additional to exchangeable potassium, nonexchamgeable potassium also has an important role in plant nutrition. Limited information about availability and release kinetics of nonexchangeable potassium in calcareous soils of Fars province is available. For this purpose, some extractants including ammonium acetate, boiling nitric acid, 0.1M nitric acid, 2M sodium chloride and water were evaluated to prediction of potassium availability for corn in 10 calcareous soils of Fars province. Release kinetics of nonexchangeable potassium was studied using 15 successive 15-min extraction with 0.01M calcium chloride. Kinetics models describing nonexchangeable potassium release rate including zero order, first order, second order, third order, parabolic diffusion, power function and ellovich were evaluated. Results showed that 1M neutral amonium acetate, 0.1M aitric acid, water and 2M sodium chloride extractants had high correlation with corn potassium uptake. Amount of potassium released among studied soils was vary in the range of 243 to 814 mg kg-1. According to R2 and SE, kinetics of nonexchangeable potassium release was described with power function, parabolic diffusion and ellovich equations satisfactorily. According to this fact that constant rate of parabolic diffusion and ellovich models had significant correlations with corn potassium uptake, it is recommended that these two models are suitable for use in these studied soils.
Research Article
M. Hojjati; M. Asadiyan
Abstract
The presence of livestock within forest stands in north of Iran, as one of the main hindrances for optimal forest managing influence the productivity of that individual forest ecosystem in a waste area. The present study was conducted to investigate the effects of the long lasting presence of cattle ...
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The presence of livestock within forest stands in north of Iran, as one of the main hindrances for optimal forest managing influence the productivity of that individual forest ecosystem in a waste area. The present study was conducted to investigate the effects of the long lasting presence of cattle on soil properties in Hyrcanian forests. The investigated area was a part of Parchinak district, Mazandaran -Sari (in 4 Livestock husbandry campus and adjacent forest stands). Soil samples were collected from soil depths of 0-10 cm, 10-20 cm using coring method (8 cm diameter) in each site randomly (n=5) for determining soil physical, chemical and biological characteristic. Results showed that some soil physical characteristics (bulk density and moisture content) and many soil chemical properties (carbon and organic matter, nitrogen, phosphorus, potassium and calcium) were higher in husbandry area than the adjacent forest stand. Also, Net N mineralization and net nitrification have been observed only in Livestock campus. Our findings indicated a significant impact of livestock presence (input of a huge amount of cattle dung and high soil compaction) on forest soil.
Research Article
M. Kargar; Mohammad Reza Javadi; S.A.A. Hashemi
Abstract
Soil erosion and sediment production are among most important problems in developing countries including Iran. In this study it has been endeavored that applicability of four (AOF, MUSLE-S, MUSLT and USLE-M) models is investigated in Srfiddasht Research Site, Semnan province, at event scale to estimate ...
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Soil erosion and sediment production are among most important problems in developing countries including Iran. In this study it has been endeavored that applicability of four (AOF, MUSLE-S, MUSLT and USLE-M) models is investigated in Srfiddasht Research Site, Semnan province, at event scale to estimate the sediment. For this, all required variables and inputs of the model have been calculated in the watershed and the estimations from considering statistical models with measured sediments of 15 cloudbursts have been compared. The results for t-student correlation test showed that there is no significant difference (at 1%) between MUSLT, MUSLE-S models and measured sediment. Based on these, it can be said that in this study, the results from these two models have higher accuracies to estimate the sediment from cloudbursts than other methods. Also, the results of evaluation and efficiency of the model using Nash-Suttcliffe criterion and root relative mean squared error (RRMSE) statistic showed that MUSLE-S and MUSLT models have higher efficiencies than other models and inefficiencies of USLE-M and AOF models to estimate sediments from cloudburst have been confirmed in the studied research station in this study.
Research Article
Ahmad Gholamalizadeh Ahangar; B. Kermanizadeh; S.K. Sabbagh; A. Sirousmehr
Abstract
This investigation was conducted in order to evaluate the direct effects of organic and bio - fertilizers on yield components of two native wheat cultivars, Bolani and cross - Bolani. The experiment conducted as a factorial in a completely randomized design with three replications. Treatment includes ...
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This investigation was conducted in order to evaluate the direct effects of organic and bio - fertilizers on yield components of two native wheat cultivars, Bolani and cross - Bolani. The experiment conducted as a factorial in a completely randomized design with three replications. Treatment includes fertilizer factor: vermicompost (F1), vermicompost + compost (F2), vermicompost + mycorrhiza (F3), compost + vermicompost + mycorrhiza (F4), compost (F5), mycorrhiza + compost (F6), mycorrhiza (F7) and control (no fertilizer application F8) and cultivar factor includes two cultivar Bolani (C1) and cross - Bolani (C2). The results showed that the interaction effect of combined treatments (F7C2) of high yield (1.13 g.pot-1) obtained. The treatment combination (F7C2) of (0.355) was highest harvest index. The high correlation between weight per plant with plant height, spike length, grain yield and harvest index were observed. Generally the combined application of vermicompost and mycorrhiza cultivar cross - Bolani is more suitable for grain production.
Research Article
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.
Research Article
H.R. Rafiei; M. Shirvani; T. Behzad
Abstract
The remediation of soils and water contaminated with heavy metals generate a great need to develop efficient adsorbents for these pollutants. This study reports the sorption of lead (Pb) by bentonite (Bent), and sepiolite (Sep), that were modified with cetyltrimethyl ammonium (CTMA+) organic cations. ...
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The remediation of soils and water contaminated with heavy metals generate a great need to develop efficient adsorbents for these pollutants. This study reports the sorption of lead (Pb) by bentonite (Bent), and sepiolite (Sep), that were modified with cetyltrimethyl ammonium (CTMA+) organic cations. The natural and surfactant modified clays (organo-clays) were characterized with some instrumental techniques including XRF, XRD, FTIR and SEM. Sorption studies were performed in a batch system, and the effects of various experimental parameters including contact time and initial Pb concentration were evaluated upon the Pb sorption onto sorbents. Maximum sorption of Pb was found to be, 83.26, 71.36, 56.25 and 37 mg g-1 for Sep, CTMA-Sep, Bent and CTMA-Bent adsorbents, respectively. The Pb sorption data were fitted to both the Langmuir and Freundlich models. The Freundlich model represented the sorption process better than the Langmuir model. Lead sorption rate was found to be considerably slower for organo-clays than that for unmodified clays. Sorption kinetics was evaluated by pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The sorption processes of organo-clays followed intraparticle diffusion kinetics. The results showed that the cationic surfactant modified bentonite and sepiolite sorbed less Pb than the unmodified clays.
Research Article
M. Rezaei; M. Nohtani; A. Moghaddamnia; A. Abkar; M. Rezaei
Abstract
One of the most important problems in the management and planning of water resources is to forecast long-term precipitation in arid region and hyper arid regions. In this study, statistical downscaling model (SDSM) is used for study of climate change effects on precipitation. The data used as input to ...
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One of the most important problems in the management and planning of water resources is to forecast long-term precipitation in arid region and hyper arid regions. In this study, statistical downscaling model (SDSM) is used for study of climate change effects on precipitation. The data used as input to the Model are daily precipitation of Kerman and Bam synoptic stations, NCEP (National Centers for Environmental Prediction) data and the A2 and B2 emission scenarios HadCM3 for the reference period (1971-2001). Using HadCM3 A2, B2 data the precipitation for three period (2010-2039), (2040-2069) and (2070-2099) are predicted and compared with the reference period. We used the first 15 years data (1971-1985) for the calibration and the second 15 years data (1986-2001) for model validation. Research results showed that the precipitation will change and Change directions are positive in some months and negative in other months. After the examination function Indexes results from SDSM model shown that this model has better accuracy and a high ability to predict precipitation in arid region than hyper arid region.
Research Article
A. Araghi; M. Mousavi Baygi; S.M. Hasheminia
Abstract
Period and trend are two main effective and important factors in hydro-climatological time series and because of this importance, different methods have been introduced and applied to study of them, until now. Most of these methods are statistical basis and they are classified in the non-parametric tests. ...
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Period and trend are two main effective and important factors in hydro-climatological time series and because of this importance, different methods have been introduced and applied to study of them, until now. Most of these methods are statistical basis and they are classified in the non-parametric tests. Wavelet transform is a mathematical based powerful method which has been widely used in signal processing and time series analysis in recent years. In this research, trend and main periodic patterns similarity in temperature and vapor pressure has been studied in Babolsar, Tehran and Shahroud synoptic stations during 55 years period (from 1956 to 2010), using wavelet method and the sequential Mann-Kendall trend test. The results show that long term fluctuation patterns in temperature and vapor pressure have more correlations in the arid and semi-arid climates, as well as short term oscillation patterns in temperature and vapor pressure in the humid climates, and these dominant periods increase with the aridity of region.
Research Article
F. Ahmadi; F. Radmanesh
Abstract
The temperature is one of the essential elements in formation of climate and its changes can alter the climate of each region, Therefore study of temperature changes at different spatial and temporal scales is devoted a large part of research to climatology. The mean temperature changes of the northern ...
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The temperature is one of the essential elements in formation of climate and its changes can alter the climate of each region, Therefore study of temperature changes at different spatial and temporal scales is devoted a large part of research to climatology. The mean temperature changes of the northern half area of Iran (18 Synoptic stations) in monthly or annual scales (1961-2010) are tested with using non-parametric Mann-Kendall test and elimination of all auto-correlation coefficients. To determine the slope of temperature gradient, the Sen’s slope estimation method was used. The results showed that 61% of the stations have experienced a significant increase in annual scale, in expect of Urmia, Zanjan, Qazvin and Gorgan stations. Arak is also a significant decrease, Torbate Heydarie and Saghez have experienced non-significant negative trend in annual scale. In monthly scale, number of months with increasing trend was greater than decreasing trend. April, September and October have significant increasing trend in most stations. December has lowest changing in compare with others. In conclusion, the studied temperature area in past half century 1.15 C is increased
