فهرست مطالب نادرقلی ابراهیمی

Sewage sludge is a semisolid residual material resulting from the sedimentation of the suspended solid during the wastewater-treatment processes. Since large amounts of sludge are being produced, different ways of disposal have been introduced. One tempting option is to use it as fertilizer in agricultural fields due to its high contents of inorganic nutrients and organic materials. However, the presence of contaminants considerably restricts the application of sewage sludge for the fertilisation and reclamation of soils. Because of the high toxicity of organic pollutants and their irreparable effects on the environment, the aim of this study was to investigate the diversity of organic pollutants in sewage sludge, their limit values for agricultural lands, and the fate of them in the soil. Also methods of analysis of organic trace compounds have been compiled. Some of the most frequently detected contaminants in sewage sludge are polycyclic aromatic hydrocarbons, polychlorinated biphenyls, di-ethylhexylphthalate, nonylphenol and nonylphenol ethoxylates, linear alkylbenzene sulphonates, adsorbable organic halides, polychlorinated dibenzodioxins and furans. These pollutants in the soil may undergo sorption by mineral particles, degradation by soil organisms or transportation with water or soil particles over long distances. Extraction of the sludge sample, subsequent clean-up of the extract and final analysis by either gas or liquid chromatography are methodologies for determining the concentration of organic pollutants in sewage sludge. Novel techniques in extraction such as ultrasonic extraction, microwave-assisted extraction, and pressurized liquid extraction require less solvents reagents and smaller sample siz, are more automated and reduce the number of analytical steps. This study show a better understanding of variety of organic pollutants in sewage sludge, their analytical methods and limit values that is imperative to restricting legislation and specification suitable properties of sludge for land application.

The term “Specific Surface Area” (SSA) refers to the area per unit weight of soil. SSA is a fundamental soil property that can be used as an indicator of soil behavior (Utkaeva, 2007) to explain many of the physical and chemical phenomena of the soil: including fertility-determining components (such as the water holding capacity, the adsorption of plant nutrients, and the amount of organic matter) (Voronin, 1975). Measurement of specific surface area is time-consuming and relatively expensive; therefore, its estimation by routinely measured soil variables is preferred. In the present paper two pedotransfer functions for estimating of total SSA (including external and internal specific surface area) was presented, one a multivariate pedotransfer function based on the standard deviation of the diameter of soil particles and clay percent and second an exponential pedotransfer function based on slope of linear regression equation of logarithmic PSD Curve.

In arid and semi-arid regions, due to shortage of permanent surface water resources the optimal use of groundwater becomes important. In this regard, the storage of sub-surface flow within alluvial reservoirs of underground dams appears to be economical, and cost-effective. In some cases, because of the lack of construction materials at the site, the cost increases. In this case a combination of available construction materials and bentonite can meet the required criteria. In this research, by constructing a physical model of underground dam the effect of adding bentonite on decreasing horizontal saturated hydraulic conductivity in non-cohesive soil was investigated. For this purpose, 2, 4 and 6% (by weight of dry soil) of bentonite was added to the soil and after compaction by using a model, hydraulic permeability was measured. The results indicated that the hydraulic conductivity decreases with increase in the bentonite content due to the high specific surface area and high swelling potential of bentonite. Also hydraulic conductivity was reduced because of steep slope (up to 4% of bentonite) and with further increase in hydraulic conductivity the reduction rate was slowed down so it can be said that the relationship between the logarithmic graph of hydraulic conductivity and the bentonite content can be represented by a linear model. Based on this model, 4.6 percent of bentonite is required to reduce the saturated hydraulic conductivity of a noncohesive soil equal to the saturated hydraulic conductivity of the soil used in the core of the Sanganeh underground dam (in a similar relative compaction).

One of the most widely used geotechnical parameters is hydraulic permeability, which is affected by pore distribution and surface area of soil particles and any parameters cause a major change in hydraulic permeability. In the present study the effect of adding hydrated lime and mixture of rice husk ash and hydrated lime at the ratio of 1:1 on horizontal saturated hydraulic conductivity was examined by using of sample physical model. Mixtures of lime and rice husk namely: 2, 4 and 6 % by weight of dry soil) were added to a non-cohesive sample, and hydraulic permeability was tested after 28 days. The results showed that addition of lime to the soil increased its hydraulic conductivity. Addition of 4 % mixtuer yielded the maximum hydraulic conductivity. Addition of more lime decreased the hydraulic conductivity, although greater than hydraulic conductivity of control sample. Results showed that rice husk ash and lime mixture acts as a catalyst and accelerates the pozzolanic reaction, which in turn causes a partial decrease in the hydraulic conductivity of sample. These results are attributed to effects of two processes of cation exchange and pozzolanic reaction between lime and rice husk ash on the hydraulic conductivity.

Human activities caused global warming and climate change and threaten agricultural production. The decline in water quality and quantity are the main constraints to food security, occupation, as well as the cause for social problems. Biosaline agriculture is one of the methods for agricultural production using saline soil and water. One of the chains of Biosaline agriculture is plant production with saline water. In this method of agriculture halophytes cultivation under a saline condition with optimum irrigation and soil management is considered. For the development of halophyte plants, seed production is the main input. Amongst halophyte species, Salicornia is considered for the development of the coastal area in the north and south of Iran. This is because of its extractable oil and high seed production using sea water. The objective of this paper is the orientation of experts for seed production, agronomic requirements, and the growth stages requirements of two Salicornia species. Salicornia bigelovii and S. persica produced 1.9 and 1.5 ton ha-1 of seeds, respectively in Yazd, Iran. To achieve the maximum yield, the sowing date is very important because of the photoperiod sensitivity during the flowering stage. Irrigation and fertilizer requirement supply are also important during this sensitive growing stage.

Mountainous rivers have characterized by steep slope, roughness due to bedrock and coarse aggregation, bed and marginal vegetation as well as severe and rapid spatial displacement of the surface substrate morphology. The protection role of vegetation in the river bank is known as an economic and environmental option that decreases hydraulic conductivity power of the river through the rising of roughness coefficient and rising water level. This study aimed to estimate the flow resistance and roughness coefficient of the river that is affected by the physical and biophysical factors of the Shahr-chay River bed in West Azerbaijan in three selected river reach. Results showed that none of the proposed equations for estimation of roughness coefficient depend on energy slope, but in general, without affecting flow, roughness coefficient in mountain streams depends only on the degree of submergence. Marginal trees can affect Froude number by increasing margin pressure and friction forces, also, enhancing the hydraulic depth, less than critical depth. It was also found the equation for estimating roughness coefficient both with and without marginal trees, have different coefficients and can provides roughness coefficient prediction possibility for mountainous rivers. Comparing the obtained relations both with and without its fringe of trees showed that fringe trees can increase the flow depth and roughness coefficient. Coefficient of determination of all mathematical relations was above 0.99 and calculated relative error was 0.001- 0.008 that demonstrates the suitability of the model to estimate the roughness coefficient.

Being located in a(semi-)arid region, Iran has been facing severe droughts in recent years complicated by the increasing urbanization. These conditions have led to a growing pressure on renewable water resources and, greater attention has been, therefore, drawn to efficient use of unconventional water resources such as urban and domestic effluents. Wastewater reuse is of great importance for the study area as a solution to overcome the growing demand for water. At the time of this study, the effluent from Arak wastewater treatment plant (WWTP) was being discharged into the Mighan desert where it is reused by downstream farmers in an unplanned manner. Concerns over public health and introduction of pollutants into soil, water, and agricultural products call for a well-planned agricultural reuse policy based on investigations of the effluent quality. The present descriptive, cross-sectional study was, therefore, conducted to determine the quality parameters of the effluent from Arak WWTP against the relevant standards and to determine its usability for irrigation. For this purpose, samples were collected from the effluent and the required tests were performed. Results revealed average values of 49.65, 23.26, and 1.93 mg/l for COD, BOD5, and DO, respectively, and 0.0564, 0.08, and 0.512 mg/L, respectively, for the heavy metals of Cadmium, copper, and lead. These values are in compliance with the limits recommended by Iran Environmental Protection Organization for wastewater reuse in agriculture. Total and fecal coliforms were, however, found to be 877.882 and 379.5588 per 100 mL and the average number of parasite eggs was 0.524 per liter, which violate the relevant standards. Based on the result obtained, the effluent seems to have no limitation for reuse in agricultural irrigation except for its total and fecal coliforms. Thus, disinfection and continuous monitoring of the effluent along with upgrading of the WWTP facility are strongly recommended for its effluent to be reusable. Over all recommendation for agricultural reuse of the effluent can be certainly made once in-depth research has been carried out.

The riverbed and margin vegetation causes to increase in roughness against flow, decrease in average flow velocity, reduce water-energy, and alterations in layer velocity distribution (the flow velocity profile) across the river. In current experimental research, the effect of branching vegetation on the stream flow and bed formation is analyzed. The flow conditions are examined in experimental channel with 7 meter length, 25 cm width and height through different flow rates (3,5,7 lit/s) and slopes under different(0.001, 0.003, 0.005) and densities of vegetation (50, 25 and 12 percent). According to the processed data, it can be implicated that the difference between flow level, substrate, and rate is affected by the types of vegetation density; thereby existence of vegetation causes resistance to flow and depth increment. In all experiments, through the vegetation density increment, the bed erosion increases compared with the primary condition in which the most and least alterations are observed in 50 and 12-percent density, respectively. In the condition of equal flow rate with density increment, the flow depth is increased. The bed particle displacement in the section covered by vegetation is increased through density increment in which flow level in 50 is more than 25 and 12-percent density, as well as, flow substrate erosion and alteration whereas sediment (particles accumulation) is appeared frequently under less density at the end of section covered by vegetation.

Some rhizobacteria by various mechanisms influence plant growth as they are called plant growth promoting rhizobacteria (PGPR). Scientists identified some PGPR characters involved in promoting plant growth, while all these characters are not able to study. The aim of this study was to evaluate PGP activities of bacterial isolates, (45 isolates belonged to rhizobium and 2 bacterial isolates belonged to Pseudomonas fluorescens), which were isolated from alfalfa (Medicago sativa) rhizosphere and root nodules grown around Zanjan.
These bacteria were isolated from alfalfa roots grown around Zinc industries in Zanjan province. After bacterial isolation and purification from root and soil samples, isolates were screened in vitro for plant growth promoting traits such as IAA (Indole Acetic Acid), ACC- deaminase (Amino Cyclopropan Carboxylate), HCN (Hydrogen Cyanide), siderophore, chitinase production and mineral and organic phosphate solubilization activities.
The results indicated that 43 bacterial isolates produced IAA (4.04- 4.95 μg/ml) and 15 isolates produced ACC- deaminase (0.23- 1.05 μg/ml). Only one isolate (Rm66) produced high amount of HCN. Qualitative siderophore production was observed in 9 isolates. None of the isolates produced chitinase. Solubilization of mineral phosphate was commonly detected in 19 isolates (4.33- 5.86 μg/ml), and 15 isolates solubilized organic phosphate (1.66- 144.28 μg/ml).
Discussion and This study shows that most of the bacterial strains which isolated from alfalfa cultivated lands had PGP activities and also a good potential to increase plant growth after inoculation with to seeds as eco- friendly fertilizers.

The saturated hydraulic conductivity is one of the most important and widely used geotechnical parameters. This parameter depends on properties of the fluid, pore size distribution, and characteristics of the solid surfaces. Because the latter two are not necessarily constant, the hydraulic conductivity may vary significantly. So far several empirical relationships for estimation of the hydraulic permeability with respect to the type of materials have been presented. In this research seven applicable method including Terzaghi, Kozeny-Carman, Chapuis and Aubertin, modified Navfac, Shahabi et al., Mbonimpa et al. and Chapuis were evaluated. Four samples of sandy soils (R1 to R4) with a rather wide range of particle sizes were prepared and were compacted within the Plexiglas box. After providing the head of 0.5,1 and 1.5 meters; flow discharge and static pressure were measured which result phreatic and iso-potential lines extraction. By applying the results of the model, the accuracy of some common methods used in the estimation of saturated hydraulic conductivity of sandy soils was evaluated. For the samples (R1 to R4), the coefficient of permeability was 0.0051, 0.048, 0.076, and 0.19 cm/s respectively. Due to the limited range of input parameters, the method of Shahabi et al. can be used only for the R4 sample; so this method was discarded from statistical analysis. Comparing the results of laboratory test with common methods shows the methods of Kozeny-Carman and Chapuis and Aubertin were more accurate according to the highest R2 and lowest RE and RMSE. These methods were based on effective parameters and the results of accurate laboratory studies. The method of Mbonimpa et al. (2002) indicates the maximum deviation from observed values which may be due to the sensitivity of this model to void ratio (e). Also the results shows by increasing of void ratio the error of Mbonimpa et al. method increases.

Application of Neuro-fuzzy and tree regression models is not too old in hydrology of river sediments and also in watersheds and in this regard, sediment rating curves have been identified as the most common method for estimating sediment. In this study for comparison and correction of estimation methods of river sediment load, estimated rates of several uni-variate types of sediment rating curves and a multivariate type of sediment rating curves were investigated with Neuro-fuzzy and tree regression models in five selective hydro-metric station of different climatic zones of Iran and with various indexes of the accuracy and the precision. The results show that the mean of the accuracy index of Neuro-fuzzy and tree regression models in selective stations are 151 and 536 percent respectively which shows low efficiency compared with sediment rating curves. The results of the application of multivariate sediment rating curve in various station shows that the rate of the accuracy index of multivariate sediment rating curve in the best case is belong to Glinak station with the rate of 1.12. Also the average value of the accuracy index of multivariate sediment rating curve is 1.15 which is an acceptable amount to the other considered various methods.

In order to investigate of geological formation effects on sediment yield in Gharah Kahriz watershed at first by overlaying the base maps such as land type, geology, slope and vegetation, the unit land map were obtained. The amount of sediment yield calculated using MUSLE model in each homogen unit. In order to achieve the objectives of the study, units that was widespread in the region and were almost homogenous in land use, slope and vegetation and the only difference was the type of geological formation, were selected. The results show that the maximum amount of sediment yield during flood events were observed in Kmm­l unit that contains layers of limestone and marl with average of 13.34 t.ha-1, and the minimum amount of sediment yield belongs to the Js unit that compound of Jurassic sandstone with average of 0.20 t.ha-1.

Assistant Professor¡ Soil Conservation and Watershed Management Institute (SCWMRI)¡ Tehran¡ Iran. The saturated hydraulic conductivity is one of the most important and widely used geotechnical parameters. This parameter depends on properties of the fluid¡ pore size distribution¡ and characteristics of the solid surfaces. Because the latter two are not necessarily constant¡ the hydraulic conductivity may vary significantly. So far several empirical relationships for estimation of the hydraulic permeability with respect to the type of materials have been presented. In this research seven applicable method including Terzaghi¡ Kozeny-Carman¡ Chapuis and Aubertin¡ modified Navfac¡ Shahabi et al.¡ Mbonimpa et al. and Chapuis were evaluated. Four samples of sandy soils (R1 to R4) with a rather wide range of particle sizes were prepared and were compacted within the Plexiglas box. After providing the head of 0.5¡1 and 1.5 meters; flow discharge and static pressure were measured which result phreatic and isopotential lines extraction. By applying the results of the model¡ the accuracy of some common methods used in the estimation of saturated hydraulic conductivity of sandy soils was evaluated. For the samples (R1 to R4)¡ the coefficient of permeability was 0.0051¡ 0.048¡ 0.076¡ and 0.19 cm/s respectively. Due to the limited range of input parameters¡ the method of Shahabi et al. can be used only for the R4 sample; so this method was discarded from statistical analysis. Comparing the results of laboratory test with common methods shows the methods of KozenyCarman and Chapuis and Aubertin were more accurate according to the highest R2 and lowest RE and RMSE. These methods were based on effective parameters and the results of accurate laboratory studies. The method of Mbonimpa et al. (2002) indicates the maximum deviation from observed values which may be due to the sensitivity of this model to void ratio (e). Also the results shows by increasing of void ratio the error of Mbonimpa et al. method increases.

Estimation of hydraulic conductivity is a basic requirement in the design and implementation of underground dams. Evaluation of the materials used in the body of the underground dam in accordance with the standards and principles of design is essential. The question is whether experimental study of the materials used in the core of underground dams considering hydraulic conductivity parameters can produce an appropriate and easy model for estimation of saturated hydraulic conductivity. A new method was developed to prepare nine cohesive soil samples from a physical model of square cross-sections of three Plexiglass boxes having dimensions of 20 × 20 × 30 cm and a total height of 90 cm were used. The water level could increase toa head of 2 m on the model. The data was recorded at the 0.5, 1, and 1.5 m water heads. Stepwise regression was used to obtain data and present an equation for the saturated hydraulic conductivity coefficient. Two relationships for hydraulic conductivity of compacted soils were developed from the data. The secondary porosity was calculated according to Chapuis theory and nonlinear regression using ksat as a function of the secondary porosity exponent was introduced. The ksat curve and Srcwere drawn in linear formin a graph where axis x = w (soil moisture) and axix y = ρw/ρd.The charts demonstrate that Src and ksatare dense sticky with appropriate estimates to obtain lift.

Climatic conditions in arid and semi-arid regions, poor vegetation cover and mountainous conditions of watersheds concentrates surface water as floodwater and cause vital and financial damages in industrial, urban and rural areas. Runoff threshold is one of most important factors in accurately estimation of flood volume and intensity for designing and securing constructive projects which saves expenses and leads to optimum dimensions of structures. In this research, rainfall simulator was used to investigate the effective factors on runoff threshold. Rainfall intensities of eight to 40 mm/h in periods of 15, 30, 60 and 120 minutes were simulated and runoff thresholds were measured. Acceptable methods for estimation of runoff threshold were introduced based on rainfall characteristics and pedology and geology parameters using measured data and multivariable linear and nonlinear regression methods. Results demonstrated that the rainfall volume and intensity as climatic factors, vegetation cover and slope as terrain factors and soil texture as pedologic factors are the most effective ones in runoff threshold. The relation of independent factors and their partnership in runoff threshold is statistically acceptable for the research area. The results showed a significant correlation (R2=0.98) between estimated and viewed runoff threshold.

Quantitative analysis of runoff and estimates of stream flow in gauged basins and its transferring to ungauged sites has special importance for water resources planning, watershed and agricultural lands management, as the layout and optimal design of diversion structures and flow control need runoff information with different probability levels. In this research, runoff information of hydrometric stations which located in river catchments of Isfahan, Markazi, Qom, Tehran, Hamadan and Qazvin provinces was collected and investigated. In this regard, such stations which included data with the appropriate quality and quantity were selected in a common period of time. In this case study, results of cluster analysis concluded three homogeneous regions of watershed based on independent variables. According to mean annual runoff probability analysis; the best statistical distribution was fitted and runoff values were determined with return periods of 2 to 100 year. Also, regional runoff models based on hydrological and morphometric parameters were extracted with different return periods for each homogeneous region. In each homogeneous region, evaluation of regression models obtained was carried out using a number of hydrometric stations control. In this case study, area, average slope, main river slope, length and gravilus coefficient of watershed were detected as the most influential parameters in estimation of runoff. Root Mean Square Error (RMSE) for models represented minimum values of 1.2, 5, 7.6 with two years return period and maximum values of 14.4, 32.8 and 18 with 100 years return period in the first, second and third homogeneous groups, respectively.

Mathematical models are widely used in water engineering as valuable tools to simulate the qualitative and quantitative aspects of water flow conditions. In This study، mathematical relationships derived from the physical models were used where the roughness coefficient was as a function of water depth and speed، and type of vegetation، to simulate the water flow by FASTER model in Karoon river. The hydrographic data of years 2003 and 2004 in three hydrometric stations were used as the minimum، maximum and average values for measurement of the model accuracy. Comparing the water level simulated by the FASTER model with fixed roughness coefficient of 0. 03 and variable coefficient and corresponding values measured by the model، indicated that the variable “n” can be improved the model accuracy. The results showed that the predicted surface roughness obtained from the FASTER model was well fitted by observed values. In this case، the correlation of surface roughness of the mathematical model with variable coefficient is equal to R2=0. 932 and with a constant roughness coefficient is R2=0. 799. This means the estimations of the mathematical model was closed to actual conditions of the river values with high accuracy.

Vegetation rough¬ness's coefficients are the main parameters used to determine river flow characteristics and are known to depend on the flow condition (depth and velocity) as well as vegetation condition (type and density). Flume experiments were conducted to investigate the vegetation density for submerged vegetation in river bed, banks, and flood plains. Artificial plastic plant (shrub type), were laid on the floor of a 14 meter long and variable slope flume facilitated in the Hydraulics Laboratory of the Soil Conservation and Watershed Management Research Institute (SCWMRI), Tehran, Iran for this study. The Manning's (n) values were estimated for different slopes, discharges, flow depth and vegetation densities. The results revealed that the Manning roughness coefficient (n) increases as vegetation density increases, while it decreases when the flow depth and velocity increase. The results also showed that the roughness coefficient is not constant and is a function of the flow velocity and depth of water. Significant variation of the Manning's (n) cpefficient with flow and vegetation conditions urges the consideration of the flow and vegetation conditions in estimation of the Manning roughness. Three equations are suggested for estimation of roughness coefficients for rivers and flood plains, with different states of vegetation density, flow depth and velocity.