farshid taran

Saline soil refers to soil with a high concentration of ions such as sodium and chloride, which destroys structures and construction materials. Thus, it's crucial to understand their nature and behavior. This study examines the effect of salinity on the compaction and shear characteristics of clayey soils by adding two types of salt, sodium chloride, and sodium sulfate, with different concentrations (0.5%, 1%, 2%, and 5%) to two clayey soils in Iran. Eighteen soil samples were prepared, and tests were carried out in three repetitions. The results showed that the samples' optimum moisture content and maximum dry density were within the range of 20-23%, and 1.56-1.63 gr/cm-3, respectively. These changes were within acceptable tolerance limits, suggesting that salt concentration has a negligible effect on the compaction characteristics of clayey soils. However, salinity concentrations significantly affected the shear strength parameters. Adding 0.5% sodium sulfate decreased cohesion by 50% and 35% in the high and low plastic clayey soils, respectively. Similarly, 0.5% sodium chloride reduced cohesion by 47% in the low plastic soil and 35% in the high plastic soil. Furthermore, the internal friction angle increased by 20% in the low-plastic soil and 34% in the high-plastic soil with 0.5% sodium sulfate. It was also found that the type of anions and cations, as well as the plasticity of soils, play a crucial role in describing the relation between pore water salinity and shear parameters of soils.

Greenhouse cultivation, with its potential to control environmental conditions and optimize the use of water and soil resources, represents a fundamental approach to agricultural production. However, the efficiency and effectiveness of greenhouses require compliance with various criteria, including hydrology, environmental factors, soil science, and particularly climate conditions. Therefore, conducting feasibility studies is essential before implementing greenhouse construction projects. This study evaluates the climatic conditions of the Nikpey region in Zanjan Province for establishing a 34-hectare greenhouse complex. To achieve this, the suitability of meteorological variables—such as precipitation, temperature, relative humidity, wind speed, sunshine hours, and cloudiness—over a 21-year period (2002–2022) was assessed using the Analytic Hierarchy Process (AHP) method. The results indicate that the average annual temperature is 11.9°C, and the region falls within the normal drought class (SPEI) for approximately 40% of the studied period. The annual cooling and heating degree days were calculated as 245.1 and 2883.3 degree-days, respectively. On average, the region receives 2975 hours of sunshine annually, with approximately 34 fully cloudy days per year. Predominant annual wind speeds range between 3.5 and 5.8 m/s, with the highest wind speed (25 m/s) recorded from the south. Based on the climatic analysis, Nikpey requires heating for 6 months,, and only natural ventilation for 4 months. Overall, the cold-dry climate of the region is classified as moderately suitable for greenhouse establishment. However, the primary challenge in the target area is the high annual maximum wind speed, necessitating careful selection of greenhouse designs that align with climatic standards.

As a result of the development and expansion of cities, growth and development of industries and technology, various pollutants have entered the environment. The pollutions resulting from the discharge of industrial effluents, consumption of fuel, discharge of municipal sewage and the use of sludge from sewage treatment as a soil fertilizer have caused harmful effects affecting humans and living creatures and changing ecosystems. Meanwhile, as a heavy metal, cadmium is very important due to its high mobility and toxicity in low concentrations.Various methods have been developed to remove heavy metals from contaminated water and soil, and surface adsorption is one of the most efficient methods. Various surface adsorbents such as clays, zeolites, dry plants, agricultural waste materials, biopolymers, metal oxides, microorganisms, and volcanic ash have been used to remove heavy metals. Iron nanoparticles with zero charge (nZVI) is a new technology that has successfully been used to remove various metal ions. Nanoparticles are special adsorbents that are used for remedial purposes due to the presence of significant specific surface area that leads to high density of exchange sites and metal removal capacity. Basically, iron nanoparticles have been introduced as effective reductants and catalysts for a wide range of common pollutants such as organochlorine compounds and metal ions.Cleaning water environments of heavy metals can happen as a result of surface absorption by absorbent materials such as nanoparticles. The aim of the present study is to investigate the effect of iron nanoparticles in removing cadmium from water environments.

Nanoscale iron particles with zero charge can be prepared in aqueous environments by reduction of ferric iron or ferrous iron by sodium borohydride or by decomposition of pentacarbonyl iron in organic solvents or argon. In this study, the synthesis of iron nanoparticles by sodium borohydride has been used. For the synthesis of nanoparticles, 7.823 grams of iron sulfate II (FeSo4.7H2O) was dissolved in 200 ml of distilled water in the presence of ethanol. After setting the pH of the suspension at 6.8, 0.8 grams of starch and 1.8 grams of sodium borohydride were added to the solution. The nanoparticles were separated from the solution using a centrifuge and washed with ethanol. All steps were performed in the vicinity of nitrogen gas and finally the synthesized nanoparticles were dried under nitrogen gas. Finally, by using microscopic methods, images with very high magnification of the material are obtained. In this study, the shape and morphology of produced nanoparticles were investigated using SEM.To investigate the effect of nanoparticle and pollutant concentration on removing efficiency, factorial statistical design with cadmium concentration treatment at 9 levels (10, 25, 50, 75, 100, 200, 300, 400 and 500 mg/liter), and treatment with zero amount of nano iron in three levels (0.025, 0.05 and 0.1 g) was applied. The effect of contact time on removal efficiency was investigated at 10, 30 minutes and 1, 4, 8, and 24 hours, and the effect of alkalinity was investigated at pHs of 4, 6, 8, and 10. In all stages, the concentration of cadmium in the purified solution was measured using an atomic absorption device.

With the passage of time, the amount of absorption or removal efficiency increases, but after 4 hours, its changes are not statistically significant. The increase in removal efficiency with the passage of time is due to the fact that with the passage of time the formation of holes and corrosion on the surface of iron increases, as a result of which the cross-sectional area of absorption and removal efficiency also increases. In addition, the active sites for cadmium absorption change and the number of products resulting from the reaction of iron in the water environment increases, which also causes an increase in the removal efficiency with increasing retention time.The results showed that the absorption efficiency decreases with the increase of the initial concentration of cadmium, which means that iron nanoparticles have a limited capacity to absorb cadmium. Examining the effect of the initial concentration of the ions of the adsorbed material showed that firstly, the more concentrated the solution is in terms of the number of ions, the better the absorption is, and secondly, the number of active sites for absorption gradually increases with the increase in the process time and the increase in the number of ions absorbed on the adsorbent decreases, so that the rate of absorption decreases significantly, leading to the formation of balance in absorption.The greater the amount of iron nanoparticles, the greater the number of active surfaces participating in metal absorption, and as a result, it holds the absorbed cadmium with greater force. The results of placing cadmium-contaminated nanoparticles indistilled water (Figure 5) showed that in high doses of iron nanoparticles, a smaller amount of cadmium was absorbed and re-entered the environment. With the increase in the initial concentration of cadmium, its release has also increased, because, as mentioned above, the number of occupied sites has increased and the amount of holding energy per ion has decreased, causing release.

As the concentration of the pollutant increases, due to the limited capacity of the adsorbent, the efficiency of absorption decreases, which means that with the saturation of the absorption sites, it is not possible to absorb more of the pollutant. On the other hand, with the increase in the amount of adsorbent, the absorption efficiency increases due to the increase in the number of absorption sites. Also, by increasing the amount of absorbent and pollutant, the possibility of collision between cadmium and iron nanoparticles and the occurrence of absorption reactions increases. The high ratio of absorbent to pollutant causes a stronger bond and as a result less pollutant is released. When the adsorption surfaces of nanoparticles are occupied by the pollutant, it is no longer possible to release the pollutant and reuse these absorption surfaces, and in general, nanoparticles of iron have zero and cannot be used more than once to clean cadmium from the water environment.

The concept of virtual water has been highlighted in the 21st century as a key indicator to evaluate the optimal use of water in the production of agricultural products, especially in the face of the water shortage crisis. This study analyzed the virtual water of irrigated wheat, known as one of the strategic agricultural products, in Iran and investigated the differences in the amount of virtual water of irrigated wheat in different provinces and climates of the country. The results indicated that the amount of virtual water of irrigated wheat in Iran is in a wide range of 284-3523 m3 ton-1 with an average of 1400 m3 ton-1, being 50% higher than the average values found in a number of other countries (930 m3 ton-1). The highest amount of virtual water (1539-3523 m3 ton-1) is in the provinces of Khuzestan, Kerman, Semnan, Bushehr, Sistan and Baluchestan, Isfahan, Fars, Yazd, some areas of Qom, Kermanshah, South Khorasan, North Khorasan, Chaharmahal and Bakhtiari, and East Azarbaijan with an average of 2610 m3 ton-1. Also, the lowest amount of virtual water (284-586 m3 ton-1) can be seen in the provinces of Mazandaran, Hamedan, Golestan, Kordestan, Kohkiluyeh and Buyer Ahmad, some areas of South Khorasan, Markazi, Hormozgan, and Ilam with an average of 451 m3 ton-1. The study showed that most of the areas under cultivation of wheat in Iran (about 53% of the irrigated wheat lands) are located in areas with water shortage crisis. The advantage of wheat cultivation in terms of water requirement and water use efficiency varies in different provinces. In terms of virtual water content, wheat cultivation is suitable in two provinces of Golestan and Ardabil, which relatively do not have water shortage problems and have low virtual water content of irrigated wheat. Khuzestan province also is preferable for wheat cultivation if the irrigation management is improved, due to the suitable climate and warm weather and the possibility of using winter rains in the growing season and quick ripening of the crop. But, wheat cultivation is not suitable in some regions of Iran, especially in the central and southeastern regions. The results of this study emphasize the necessity of optimal management of agricultural water resources and the strategic selection of areas under wheat cultivation based on the national cropping pattern from the aspect of advantage of production related to water requirements, water resource limitations, improving productivity and reducing virtual water content, reducing of crop wastes, and more attention on virtual water trade of wheat.

Due to the scarcity of water resources and ever-increasing demand for it, treated wastewater, if meeting agricultural standards, can serve as an alternative or supplementary water source for achieving sustainable agriculture. In this study, considering the water shortage problem and the presence of arable lands in the province of Qazvin, especially in the Buin Zahra region, the potential of using the effluent of Qazvin’s sewage treatment plant in Buin Zahra’s irrigation and drainage network was investigated. In the first phase, the environmental status of the Buin Zahra region was studied, and subsequently, for one year (2019-2020), monthly samples were taken from the raw wastewater inflow and the treated effluent. Physical, chemical, and microbial analyses of these samples were conducted to evaluate the efficiency of the Qazvin sewage treatment plant. Based on the area's cropping pattern and the quality requirements of agricultural products, a plan for the development of the irrigation and drainage network was devised, considering the quantity and quality of the produced effluent. The evaluations included gravitational transfer, significant aquifer depletion, soil characteristics, and the area's cropping pattern. Taking these factors and the social acceptance of the plan into account, the network development was proposed using 20.8 million m3 of effluent annually, covering 2000 ha of Buin Zahra's lands, and the appropriate cropping pattern and irrigation system were determined. Finally, given the importance of health and environmental issues, a comprehensive program for monitoring the quality of various components of the plan, including effluent, soil, agricultural products, and project workers, was prepared and presented to ensure the sustainable and safe use of this resource.

Snow is an important source for water supply in the agricultural sector, electricity production in factories, groundwater reserves, and rivers. This natural resource is important since it stores water in winter with low demand and releases it in hot seasons with high demand. Melted snow flow can be very useful in low-water seasons. In arid and semi-arid regions, snow is considered a basic source of fresh water. Significant spatiotemporal changes in distribution of snow on the scale of a basin can be important in determining the time and amount of snow melting in spring. The lack of sufficient and correct information about snow reserves can lead to inappropriate use of water resulting from snow melting and, as a result, irreparable damages. Therefore, measuring the surface covered by snow and its water equivalent, along with other information such as snow density, especially in areas where snow accounts for a large share of precipitation, is essential for resource planning and management. However, it is not possible to measure it in many areas due to harsh environmental conditions. Also, the data measured at one point cannot be generalized to a wide area of a basin. Thus, the use of satellite images can be considered as one of the methods of investigating spatial and temporal changes in distribution of snow in a region.

To obtain the monthly values of snow cover (SC), snow water equivalent (SWE) and snow depth (SDepth) from January 1982 to December 2023, the FLDAS (Famine Early Warning Systems Network—FEWS NET—Land Data Assimilation System) product from the Noah 3.6.1 Land Surface model was used. This product is at latitude 90° to -60° and longitude 180° to -180° with a spatial resolution of 0.1°×0.1° in netCDF format and its images are monthly available from January 1982 until now.The non-parametric Mann-Kendall test was used to investigate the increasing, decreasing or constant trend of the data during specific time intervals in the period. The Theil-Sen slope was used to calculate the slope of the trends. The correlation of the temporal distribution of snow cover with the two meteorological parameters of temperature and precipitation was determined using the Pearson's method.

The results showed that the year 1982 with a total of 41043.04 km2 had the highest and the year 2021 with a total of 4048.12 had the lowest SC. These data indicate a 90.13 percent decrease in SC in 42 years, which is understandable considering the 35.08 percent increase in the mean temperature (from 9.49 to 12.82 ºC) in this period. The monthly average of SC in this period showed that there was no snow cover from May to October, and in April and November it was very insignificant and negligible compared to in January, February, March and December. Among these four months, January had the highest average SC.According to the Mann-Kendall test, the trends of SC, SWE and SDepth was decreasing in all the four months of January, February, March and December. Temperature and precipitation values had increasing and decreasing trends, respectively.According to the Teil-Sen slope test, SC had the steepest and gentlest decreasing slope in January and December, respectively. In the case of SWE and SDepth, the steepest decreasing slope was related to February, and the gentlest decreasing slope occurred in December. The increase in temperature had the gentlest slope in the two consecutive months of December and January and the steepest slope in the two consecutive months of February and March. The steepest and gentlest slope of decrease in precipitation occurred in March and February, respectively.The Pearson's correlation coefficient values indicated that SC, SWE and SDepth have inverse correlation with temperature and direct correlation with precipitation. Overall, SC, SWE, and SDepth were more correlated with temperature than precipitation, especially in February and March when temperature was higher than in December and January.

In this study, using the satellite images obtained from the FLDAS product, the data of snow cover, snow water equivalent and snow depth were obtained in the province of Hamedan for the 42-year period of 1982-2023. The results showed a significant decrease in the snow cover during this period, which was expected due to climate change and temperature increase. The snow cover, snow water equivalent and snow depth have had decreasing trends. The trends of the two climatic parameters, temperature and precipitation, have been increasing and decreasing, respectively. The steepest and gentlest slope of the decrease in snow cover occurred in January and December, respectively. There was an inverse correlation of snow cover, snow water equivalent and snow depth with temperature, and a direct correlation with precipitation. In general, the correlation of snowfall parameters with temperature, especially in warmer months, was more than their correlation with precipitation.

Solute transport parameters, similar to soil's physical and chemical properties, can be affected by the presence of organic and mineral soil conditioners. In this study, the effect of different levels (0, 3, and 6 weight percent) of the inexpensive and easily accessible pumice conditioner on the parameters of bromide transport in sandy loam soil columns (diameter and height of 10 cm) was investigated. The transport parameters were estimated based on the BreakThrough Curves (BTCs) by the inverse modeling of the Convection-Dispersion Equation (CDE) and the mobile-immobile model (MIM) using the CXTFIT software. The BTCs showed that bromide transport in the sandy loam soil columns, regardless of the presence of pumice was mainly equilibrium, and the CDE was more efficient than the MIM, which is based on non-Fickian and non-equilibrium transport. The peak of the BTCs (maximum relative concentration) was lower in the treatments containing pumice and belonged to more pore volume than the controlled treatment did. This indicates a lack of preferential flow and thus, a reduction in the amount of bromide consumed in the treatments containing pumice. The increase in pumice content did not have a significant effect on the parameters of mobile water fraction ( ) and mass transfer coefficient ( ) in the MIM, confirming the equilibrium transport of bromide. A 3% increase in the pumice content in the soil caused an increase and a decrease of 47% in dispersivity ( ) and Peclet number (Pe), respectively. In general, it can be concluded that the use of pumice in field conditions can prevent water loss and nutrients and reduce groundwater contamination by reducing preferential paths.

In order to better management of contaminants in porous media, it is essential to recognize their transport behavior using appropriate models. In this research, Convection-Dispersion Equation (CDE) and Mobile-ImMobile (MIM), as physical equilibrium and non-equilibrium models, respectively, were used to simulate the bromide transport (as a conservative contaminant) through undisturbed and saturated clay loam and sandy loam soil columns (diameter of 10 and height of 40 cm). To simulate the transport, CXTFIT2.1 software, in which the CDE and the MIM models are included, was used. The values of mass transfer coefficient (ω<100) and mobile water fraction (β<1) as an indicator for determining the equilibrium and non-equilibrium indicated that bromide transport behavior within these columns was anomalous or non-Fickian transport. Hence, non-equilibrium and the MIM model are suitable and more efficient than the Fickian-based CDE. The fitted breakthrough curves (BTCs) and the larger determination coefficient (R2) and the smaller Root Mean Square Error (RMSE) values of the MIM model compared to those of the CDE confirmed the effectiveness of the MIM model in simulating bromide transport in the clay loam and sandy loam soil columns.

Laboratory and field experiments have shown that dispersivity is one of the key parameters in contaminant transport in porous media and varies with elapsed time. This time-dependence can be shown using a time-variable dispersivity function. The advantage of this function as opposed to constant dispersivity is that it has at least two coefficients that increase the accuracy of the dispersivity prediction. In this study, longitudinal dispersivity values were obtained for the conservative NaCl solute transport in a laboratory porous medium saturated with tap water. The results showed that the longitudinal dispersivity initially increased with time (pre-asymptotic stage) and eventually reached a constant value (asymptotic stage). Four functions were used to investigate the time variations of dispersivity: linear, power, exponential and logarithmic. In general, because of the linear increase of dispersivity during a long time of transport, the linear function with R2=0.97 showed better time variations than the other three functions; the logarithmic function, having an asymptotic nature, predicted the asymptotic stage successfully (R2=0.95). The ratio of the longitudinal dispersivity to the medium length was not constant during the transport process and varied from 0.01 to 0.05 cm with elapsed time.

One of the mechanisms of solute transport in soil is preferential flow or flow in macropores. In this study, to investigate the influence of macropore paths on solute transport, three soil bulks composed of 3% clay, 4.2% silt and 92.8% sand in a box with 200 cm length, 100 cm width and 45 cm height were used. The first soil bulk was homogeneous (without macrpore path), the second one contained soil and layers of 5 cm thickness, composed of gravels with 2-4 mm diameter, from surface to bottom of the box (with continuous macropore layers), and the third one contained also contained soil and layers of same thickness and material, but the layers extended only to a depth of 35 cm (with non-continuous macropore layers). The transport of NaCl solution in these three soil bulks were experimented and then simulated using GeoStudio. In the soil bulk having continuous macropore layers, in comparison with the one with no macropore layer, the solute traveled the distance between the surface and the bottom in a shorter time (about 27%) and the peak concentrations were sooner observed (10-20 min). However, the non-continuous layers had no significant impact on the speed of solute transport. The GeoStudio software satisfactorily simulated the solute transport with the coefficient of determination more than 0.970 and the values of the root mean square error less than 0.25.

Soil is not only a medium for plant growth but also a transmitter of contaminants to atmosphere¡ surface water and ground water. Therefore¡ studying the movement of substances in soil is important. In this study¡ the effects of soil slope and rainfall intensity on solute transport in soil were investigated under laboratory conditions. The experiments were conducted in two sloping and not-sloping soil bulk and included injection of a conservative solute (NaCl) with two different intensities. The results showed that the soil slope increases the solute transport in the lateral direction¡ and the increase of injection intensity accelerates the solute movement towards the depths and increases the peak concentration. Solute movement was well simulated using Hydrus-2D model with the coefficient of determination (R2) between 0.848-0.907¡ the Nash– Sutcliffe efficiency coefficient (EF) between 0.805-0.907 and the low values of the root mean square error (RMSE).

Rainwater harvesting can help extremely to supply a part of the water requirements of arid regions such as Iran. In this study, the potential of Bonab city in usage of rainwater harvesting systems was investigated. For this purpose, surface areas of the various parts of the city were determined and using 13 years (2000-2012) average rainfall in different months, the volume of runoff that can occur at different parts of the city was calculated. The results showed that if total runoff of the city’s area be collected every month, 100% of public, commercial and industrial’s water requirements in the months Farvardin and Ordibehesht are provided. Also, some of the runoff in two months can be stored to compensate for the lack of the months Khordad to Mehr. Approximately, 100% of the water requirement of the months Aban to Esfand can be supplied through the runoff collected in these months. The domestic water requirement can be supplied by collecting runoff from yards and roofs of residential areas in the months Farvardin to Esfand. Also, the months Mordad and Aban can provide the lowest (0.59%) and the highest (43.25%) amount of this requirement. If the water requirement of each month be supplied by the rainfall of the same month, then 100% of the water requirement of city’s landscapes will be provided in all month except Tir and Mordad. Using the Farvardin to Khordad’ rainfall, in addition to providing the total water requirement of landscapes in these months, the lack of the months Tir and Mordad could also be provided.

The phenomenon of transport in aquifers, as heterogeneous porous media, has been the subject of research over the past two decades. Characterizing the role of dispersivity in mass transport in such media is essential to any effort in predicting the movement of contaminant in water resources. In this study, to presume heterogeneity of porous media, three types of spatiallyvaried dispersion coefficients were used. These coefficients including linear, power and exponential functions were inserted separately in the mass transport equation in porous media. Then, these models were solved analytically using boundary conditions of the first- (Dirichlet) and third-kind (Cauchy). To illustrate concentration profiles, data of continuous injection of sodium chloride ions in a laboratory soil column were used. The values of concentration in column at various times were estimated by CXTFIT2.1 code. Concentration profiles of both boundary conditions showed that at early times after the injection, dispersion coefficient of the linear model was more compatible with the experimental data and with elapsing time, results of the power model were better than those of the other two models. Moreover, the results showed that Cauchy and Dirichlet conditions were more appropriate for solving linear and exponential models, respectively.