محسن فرحبخش

The rapid development of industry and economy has led to the entry of environmental pollutants, particularly heavy metals, into the soil, raising concerns among the global community regarding public health and food security. Consequently, the awareness and assessment of these elements have become significant in predicting hazards and related diseases, as well as establishing soil quality standards. This study aimed to quantify lead (Pb) contamination using various environmental indices in a part of Shahr-e-Ray, Tehran Province. To achieve this, 44 composite soil samples were collected from the 0-20 cm soil depth. After sample preparation, some physical and chemical properties were measured using standard methods, and the total concentration of lead in the soil was determined using the Aqua Regia method. Three environmental indices, including the Enrichment Factor, Geoaccumulation Index, and Contamination Factor, were employed to assess the potential risk of lead contamination. The results indicated that all examined samples exceeded the standard and recommended limit for lead concentration in Iran, with an average of 135.99 mg/kg. In term of the Geoaccumulation Index, the samples exhibited a range of (2.46-2.90), categorizing them in the moderately to heavily polluted class. For the Enrichment Factor, all samples fell into the high enrichment class, with a range of (6.48-9.31). The Contamination Factor also classified the samples as highly contaminated, with a range of (8.25-11.24) which is mainly influenced by human activities. Continuous monitoring and surveillance of lead concentration variations in the studied soils are essential for preserving production resources and achieving food security.

The purpose of this study was to investigate the spatio-temporal variation of plant water uptake under optimal moisture conditions and drought stress. Corn and rapeseed plants with two different root development patterns were planted in pots with 48 by 62 cm dimensions in four replications. The internal space of each pot was divided into 18 almost hydraulically isolated regions and then filled with sandy loam soil. The hydraulic isolation was performed by a layer of 2.5 cm of coarse sand. Matric suction of soil was buffered, and the water use was simultaneously measured using handmade tensiometers at suction 40cm. In the end, two pots from each culture were phased with drought stress by increasing the suction of the soil to 100cm. The results showed that both plants extract water from the first (0-10 cm) and the second layer (12.5-22.5 cm) rather than deeper soil under optimal moisture conditions, and tend to uptake more water from deeper and afar regions under drought stress. The water uptake pattern was attributed to the radial and axial hydraulic resistances of roots and soil hydraulic resistance. The hydraulic resistance of soil and root (radial component) becomes more than axial root resistance which results in the less decline of hydraulic potential xylems from proximal to distal regions. Then, the high potential gradient is transversally established across distal roots and promotes water uptake.

The increased levels of Arsenic, a poison element, in the soils and waters of Hashtrood city have caused different health issues for the people. Due to the lack of information about the arsenic content of the soils, the present study was conducted to survey the soil arsenic distribution and the possibility of reducing arsenic release from the soils. For this purpose, 53 soil samples from the top layer were collected and the arsenic concentration and distribution map was determined. Additionally, in order to evaluate the effect of iron hydroxide and gypsum as soil amendments, five polluted soil samples were selected and treated with the proposed amendments; each at three levels. The results revealed that the agricultural soils of the studied area are polluted by arsenic, as its average concentration was 49.36 mg/kg, but more than 80 percent of the studied soils had a lower concentration than the standard level. The agricultural soils of Ghopoz and Ghezellou showed the highest arsenic contamination. Application of iron hydroxide reduced the arsenic releasement in different soils significantly, as 10 ton/hectare iron hydroxide application reduced arsenic solution 64.5, 82.4, 83.7, 98.9, and 100 percent in the soils of 1, 2, 3, 4, and 5, respectively. Increasing the level of iron hydroxide application decreased arsenic release more intensively. Similarly, the gypsum decreased the arsenic release significantly and its reduction was more by increasing gypsum application In comparison to gypsum, the iron hydroxide was much more effective in controlling the arsenic releasement.

The purpose of this study is to present a weighting factor for considering limitation of salinity on plant water uptake (ωsi) for the concept of Integral Water Capacity (IWC). The experiment was conducted under greenhouse conditions and included corn planting in two soil types, three salinity levels (1.5, 4, and 8 dS m-1), and three replications. After the plants were fully established, all pots were continuously irrigated with a specific salinity. The transpiration values were obtained from the weight differences of pots considering water mass balance components at different times. Cumulative transpiration was calculated at each time step and they were plotted against the drainage water salinity at the same time. Then, using the numerical derivative of the cumulative transpiration curves, the transpiration intensity curve was calculated. By fitting a logarithmic model and their relativization, the effect of salinity constraint on the transpiration was calculated and a new salinity weighting coefficient was proposed. The results of ωsi showed that the relative water uptake decreased logarithmically with increasing salinity and the salinity tolerance of corn varied in soils with different properties and a constant value cannot be reported as salinity tolerance.

High soil phosphorus (P) can increase the amount of runoff P and cause pollution of P in water bodies. In this paper, to select the best method between laboratory extracting and rainfall simulator method for determining environmental threshold level of P concentration was compared. For this purpose, surface soil was sampledfrom 30 points of Talkherood Watershed inEastern Azerbayjan with widely available P contents. After determining some of general properties, four soil P tests comprising Olsen, Mehlich-3, Iron oxide, and Soltanpour were used. Water soluble P in lab was measured and runoff soluble P of soils was determined with using rainfall simulator by applying 75 mm h-1 rainfallfor 30 minutes. Relationship between P concentrations determined by four methods with  a) water soluble soil P, as P loss index, and b) runoff soluble P, showed that environmental soil P concentration can be estimated by both lab extracts and rainfall simulation methods for lime soils of this region. As the lab extracts method are easier and less time-consuming, this method is recommended for threshold concentration estimation. Since in iron oxide method, slope difference between the two split-lines was greater than other methods and high correlation coefficients were obtained for all of the methods, as a result iron oxide method is better than others for threshold concentration estimation of available P concentration. Since changing point for dissolved reactive P was seen in 0.36 mg l-1 concentration, as a result this concentration is lower than environmental P concentration for eutrophication phenomenon.

Copper smelting and refinery factories are the final stages of a pyrometallurgical processing chain, and they cause many environmental challenges around the world. One of the most common environmental problems of these factories is toxic emissions. These toxic gases have harmful effects on the vegetation, animal species, soils, and water resources around the factories. Phytoremediation can play an important role in the reduction of the adverse effects of environmental pollutions arising from copper smelting and refinery factories. In this paper, we first discuss different types of pollutions caused by copper metallurgical factories, and present the main research approaches and studies conducted on these factories. In the second part, we provide a summary and comparison of different remediation technologies used to reduce the environmental pollutions of these factories. Besides, the advantages and disadvantages of each method is also investigated. In the third part, we review the different aspects of the phytoremediation including the effective mechanisms, different types of plants, application environments, and the effective factors. The next part includes the selection of suitable plants for the phytoremediation process applied for copper metallurgical factories and investigation of the native and cultivated hyperaccumulator plants. In addition, different efficiency indices are introduced for evaluating the phytoremediation efficiency and selecting an appropriate hyperaccumulator plant. At the final stage, some appropriate plant species for various types of phytoremediation are introduced. The effects of different environmental stresses and the possibilities of integrating phytoremediation with other remediation technologies as well as the advantages and disadvantages of phytoremediation are eventually investigated.

Phosphorus (P) loss in runoff can promotes weed and algae growth in water systems as a result of high concentrations of surface water P. As a result, relationship between available soil P and P concentrations is necessary for management of P concentrations in surface waters and for critical soil P determination. For this purpose, from 30 points of Talkherood Watershed surface soil samples with widely available P contents were selected. After determining some of general properties, four soil P tests including Olsen, Mehlich-3, Iron oxide and Soltanpour were measured. Then, soil samples were poured with imperative compaction and rainfall was applied onto 30×60 cm soil boxes on a 5% slope for 30 minutes by applying 75 mm h-1 rainfall. Their runoff was sampled in different times and their dissolved P concentration was measured. Significant correlation was obtained between dissolved runoff P and the four methods of available P for the soils. Critical concentrations of phosphorus for Olsen, Mehlich-3, Iron oxide, and Soltanpour methods were 86, 140, 52 and 49 mg l-1, respectively. Also, the four methods showed critical dissolved runoff P concentrations in narrow range of 0.38 to 0.4 mg l-1.

Disturbance in nitrogen cycle balance has a negative impact on the overall trend of sustainable development and the use of soil amendments is necessary to reduce these hazards. In order to investigate the effect of some amendments and irrigation water salinity on mass nitrate balance, a factorial experiment in a completely randomized design with three replicates was conducted. The treatments consisted of three levels of soil amendments (zero, 7.5 g/kg of raw pistachio residues and 7.5 g/kg of its biochar) and four salinity levels of irrigation water 0.5 (tap water), 5.5, 8 and 10.5 dS/m. Two pistachio seedlings were transferred to all columns and then in three stages and in each stage, 25 mg/kg N of potassium nitrate was added to the soil. After adding nitrogen, nitrate measurements were done in different times. The results indicated that the pistachio residuals and its biochar increased nitrate outflow from the soilby 9% and 52%, respectively. The nitrate concentration with the exit of about 60% of the drainage water (about 7 hours later) reached the lowest, then remained constant until complete exit.

The intensive and inappropriate use of pesticides caused environment to be contaminated. Quantifying the fate of applied herbicides in the soil is essential for minimizing their mobility in the soil and environmental pollution. The leaching and degradation of the metribuzin herbicide in three soils were investigated under laboratory conditions. Metribuzin was mobile in the soils when tested using non-aged and aged soil columns. The mobility of herbicide in the soil is related to the adsorption phenomenon in the same soil. It was found that the mobility of metribuzin in the soils 7 and 5 (with less organic carbon) was more than the one in the soil 1. The difference in the adsorption affinity of metribuzin in different soils appears to be due to differences in soil properties, such as clay content, organic matter content and pH value. The calculated half-life values in sterile and non-sterile conditions ranged from 37.92 to 105.74 days. Metribuzin persistent in the soil was corresponded to columns 1, 5 and 7 respectively.

Soil quality as "the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation. Soil quality cannot be directly measured, but it can be inference from the integration of soil physical, chemical and biological properties. This study was conducted to compare the effects of conservative, reduced, and conventional tillage on soil quality indices. Tillage treatments were no tillage, disc plow tillage, combination tillage, and conventional tillage, which have been performed for five years. The results showed that no tillage, disc plow tillage and combination tillage improved the integrated quality index of the soil (IQI) respectively as 32.79%, 21.78% and 16.82%, for the depth of 0-10 cm, 18.94%, 15.74%, 14.76% for the depth of 10-20 cm, and 17.32%, 11.62%, 16.82% for the depth of 20-30 cm as compared to conventional tillage. Also, nemero quality index (NQI) of the soil was improved in all conservation treatments as compared to conventional tillage. Also, it was revealed that the soil quality decreased as the soil depth increases. Regarding to the research findings, the no tillage system, due to improvement of the soil quality, is recommended as a beneficial practice for farmers to manage the soil in the proposed and similar areas.

There is critical need for a practical indicator to assess the potential of phosphorus (P) movement from a given site to surface waters, either via surface runoff or subsurface drainage. The Degree of P Saturation (DPS), which relates a measure of P already adsorbed by a soil to its P adsorption capacity, could be a good indicator of that soils P release capacity. For our country soils, there is not any report for DPS calculating. This study aimed to develop techniques of calculating the DPS for calcareous soils of western Azerbayjan, Uremieh Lake sub-watershed, obtaining DPS levels for calcareous soils, and evaluating DPS by use of soluble P as indicator of P runoff potential. For this purpose, 30 surface soil samples with widely P contents were selected and after determining some of general physico-chemical properties, useing of four measures of soil available P and four indices of P sorption capacity, sixteen different forms of DPS were obtained. Significant correlation was obtained between soluble P and different forms of DPS in this study. Threshold P concentration between four extractants, were obtained for Olsen, Mehlich-3, and Soltanpour ones, except in calculations with Mg as P adsorbed contributor in range of 0.4-33 percent, with 8.14 mean, and for FeO extractant, only in calculations with Ca + Mg as adsorbing one was obtained that was equal to 1.3 percent. Degree of P saturation in soils with higher than threshold P concentration values are sustainable to P runoff via surface runoff or leaching, and as a result eutrophication intensification, and for control this phenomenon should apply management practices with regard to different situations of watershed.

These days, one of the most important environmental problems is soil pollution due to the contamination by petroleum hydrocarbons. One of the methods for reducing of soil contamination is the use of the electrokinetic process for remediation of hydrocarbons contaminated soils. Electrokinetic process causes the movement of water, ions and charged particles in the soil by electric field voltage. In this study, the effect of pH control in catholyte and anolyte on electrokinetic for removal of petroleum hydrocarbons from a clay soil, was evaluated. For this purpose, two experiments; one without pH control and second with pH control (in the range of 6-9) in electrolytes were carried out. Initial concentration of petroleum hydrocarbons in soil was 5%. The amount and type of petroleum hydrocarbons in the soil samples were measured by GC-MS. The results of both experiments showed that after 30 days, and 1 Vcm-1 electric field voltage, the highest percentage hydrocarbons was near anodes with little movement in the middle column. The average of petroleum hydrocarbons removal of two experiments was 16.67% and 31.5%, respectively. In addition, in the second experiment, about 26% of paraffin hydrocarbon and 37% of naphthalene hydrocarbons were removed from the soil column.

In order to investigate the effect of urea with humic acid vermicompost and urea with humic acid mushroom compost substrate application on some nutrients concentration and some growth characteristics of maize plant (Zea mays cv. single cross 704 ), a greenhouse experiment was conducted in randomized completely design with three replications. This study compared five different types of treatments which were urea without additives (U), urea with pure humic acid vermicompost powdered form (U), urea with pure humic acid mushroom compost substrate powdered form (U), urea with impure humic acid vermicompost powdered form (U), urea with impure humic acid mushroom compost substrate powdered form (U). The results indicated that plant high, shoot dry and fresh weight were markedly higher when humic acid-urea fertilizers were applied. Also, the results indicated that the concentration of P, K and N in maize plant significantly increased by humic acid-urea experiment treatments. The greatest amount of phosphorus, potassium and nitrogen observed in treatment maize plants received urea with pure humic acid vermicompost powdered form (U), urea with pure humic acid mushroom powdered form (U), urea with impure humic acid vermicompost powdered form (U) and urea with impure humic acid mushroom compost substrate powdered form (U). The some agronomic characteristics of maize plant were markedly increased when humic acid- urea fertilizers were applied.

The environment is contaminated through intensive or inappropriate use of herbicides. Quantifying the fate of applied herbicides in the soil is essential for minimizing their mobility in the soil and environmental pollution. The adsorption behavior of the soil-applied herbicides is one of the most important factors governing its environmental impacts such as degradation, transition and leaching. To date, No studiy has been conducted to investigate the effects of DOM on the sorption of metribuzin by soils. The objective of this study was to investigate the impacts of DOM on metribuzin sorption by two defferent soils.
In this research, DOM (0, 10, 20, 40, 80 and 160 mg of OC/L) adsorption in two different soil samples was assayed under laboratory conditions at constant temperature. The effect of pH and DOM concentrations (0, 10, 40 and 160 mg/L) on metribuzin (1.5, 2, 3, 4, 5 and 6 mg/kg) adsorption was also studied. Soil samples were selected and collected from surface layers (0–20 cm). The soil samples were air-dried and passed through a 2-mm sieve. The DOM sorption in both soils was performed by adding 10 ml DOM solution with a series of initial concentrations in each 15 ml glass tube containing 1.00 g soil. All the DOM solutions contained 0.01 mol/L CaCl2 and 0.01 mol/L thymol, and the pH of the solutions were adjusted to 9.0 (about the pH of the initial extracted DOM solution) with 0.1 mol/L HCl or 0.1 mol/L Ca(OH)2. The tubes were shaken at 140 rpm for 24 h at 22°C. After centrifugation at 4,500 rpm for 15 min, the DOM concentrations in solutions (presented as OC) were measured using a total organic carbon analyzer. Sorbed organic carbon was calculated from the difference between the OC content of the DOM solution, which was initially added, and that found in equilibrium solution with the soil, of which the amount of native DOM released from the air-dried soil samples was subtracted. DOM solutions (10 ml) with different concentrations were added to the soils in 15 ml glass tubes with PTFE lined screw caps. The solid-to-solution ratios were adjusted to attain 20–80 percentage of the initially added metribuzin adsorption by the soils. All the DOM solutions contained 0.01 mol/L CaCl2 to maintain a constant ionic strength and 0.01 mol/L thymol to inhibit potential microbial activities, and the pH values of the solutions were adjusted to 9.0 with 0.1 mol/L HCl or 0.1 mol/L Ca(OH)2. Metribuzin was mixed at high concentration in acetonitrile before being added to the DOM solutions. Acetonitrile concentrations were always less than 0.1 percentage of the total solution volume to avoid the cosolvent effect. The tubes were shaken at 140 rpm for 24 h at 25°C. Preliminary studies showed that sorption equilibrium was approached within this time period. After mixing, the tubes were centrifuged at 4,500 rpm for 15 min, and 1.0 ml of the supernatant was removed into a sampling vial for analysis. All sorption samples were conducted in triplicate. The sorption experiments were conducted at different pH values in the absence of DOM by addition of HCl and Ca(OH)2 as required to solutions containing 0.01 mol/L CaCl2 and 0.01 mol/L thymol. The investigated pH values ranged from 4 to 9.5. The initially added concentration of metribuzin was 5 mg/L. After shaking and centrifugation, the pH values of the supernatants were measured using a pH meter. The samples were analyzed by gas chromatography equipped with a mass (6890N, Agilent, USA). Metribuzin sorption was calculated from the difference between the total amount of metribuzin initially added to the solution and the amount remained in the solution at equilibrium.
Dissolved organic matter (DOM) was adsorbed on the soils and the experimental data was better fitted to the Freundlich isotherm (R>0.999). The KF parameter amount of DOM sorbed on the soils were 3.82 and 0.95 L/kg for the soils of 1 and 2, respectively which suggested that the soils have low affinity to metribuzin . In the presence of DOM, the sorption behaviors of metribuzin by the soils were different. The effects of DOM on metribuzin sorption were dependent on the characteristics of soils and the concentrations of present DOM. Metribuzin sorption by soil 1 and soil 2 was inhibited in the presence of DOM. Metribuzin sorption was quantified by comparing the apparent distribution coefficient of metribuzin in the presence of DOM (Kd*) and the absence of DOM (Kd). The sorption was promoted when the ratio of Kd*/Kd was more than 1, and was inhibited when the ratio of Kd*/Kd was less than 1. The aqueous solubility, sorption, and bioavailability of metribuzin are pH dependent. The effects of pH on the metribuzin sorption by soils showed when pH increased from 4 to 9, metribuzin sorbtion by soils was decreased. When the pH was higher than 6.0, it was clear that the amount of sorbed metribuzin decreased as the solution pH increased in each soil in the absence of DOM. Metribuzin was present in both molecular and ionic forms owing to the ionization in the pH range examined in the study. As the solution pH increases, the protonic form decreases. Therefore, the sorption of metribuzin protonic form and the negatively charged surface of soils become more pronounced and the amount of metribuzin partitioned to soil decreases. In addition, an increasing pH may enhance the release of native organic matter from the soils into the solution that results in the decrease of metribuzin sorption. At the same pH, the amount of metribuzin sorbed by soil 2 was lower than soil 1 which was probably owing to the different organic matter content of the soils.
The effects of DOM on metribuzin sorption were dependent on the characteristics of soils and the concentrations of present DOM. In general, metribuzin sorption by the soils was inhibited in the presence of DOM. Metribuzin sorption by the soils also decreased with increasing the solution pH in the absence and present of DOM. The results of the study will be useful for the better understanding of the behavior of metribuzin in soils and its ecological risks.

Boron (B) is an essential plant micronutrient whose soil availability is influenced by many soil factors.Understanding the processes controling activity of boron (B) in the soil solution is important for soil fertility management. The reaction of adsorption and desorption of boron in soil determines the amount of boron that is available to plants. Adsorption–desorption processes play a major role on boron equilibrium concentration and therefore on its bio-availability. Ionic strength, pH and ionic composition in exchangeable phase are among themajor factors affecting B adsorption reactions.Reducedadsorption of boron at high pH is because of a surface potential decrease onminerals with pH-dependent charge. Ionic strength has also a considerable effect on B adsorption.Several studies have been performed inthe adsorption of boron and the effect of factors such as ionicstrength and cations has been understudied, however, the effect of sodium adsorption ratio and itsinteraction with the ionic strength on boron adsorption behavior has not been reported. In thisstudy, the adsorption isotherms of boron in the soils affected by the combined effects of ionic strengthand sodium adsorption ratio were investigated.
In order to assess the effects of ionic strength (IS) and Sodium Adsorption Ratio (SAR) on availability of B, the adsorption of B was investigated in a calcareous soil that hadlow levels of electrical conductivity, sodium adsorption ratio and available P. For this purpose, 5 g soil wasequilibrated with 20 mL of B solution (0, 2, 5, 8, 10, 15, 20 mg L-1) in 0.02, 0.06 and 0.12 M background solutions (prepared by NaC1,CaC12.2H2O, MgCl2.6H2O), at two SAR levels (20 and 100).The reaction temperature was 25◦C. The suspension was centrifuged, filtered, and a sample was removed and B was determined by Azomethine-H spectrophotometric method (at a wavelength of 420 nm). B adsorption in Soil was obtained by subtracting B in solution after filtration, from added boron.
The Langmuir isotherm waswell fitted to the adsorbtiondata based on the R2 and SEE.At different IS and SAR levels, the soil exhibited different adsorption behaviors. The effect of SAR on the boron adsorption was greater at high concentrations.The results showed the increase in sodium adsorption ratio,increased soil pH and Boron adsorption.An increase in sodium adsorption ratio up to 100 resulted in a small increase in Boron adsorption compared to SAR=20. With sodium adsorption ratio of 100, soil pHincreased from 8.3 to 8.7. At about PH=9.5, maximum adsorption occurs because boron dissociation is greater when pka = pH. Increasing ionic strength increased the boron adsorption; the absorption rate wasmuch higher at higher ionic strength.Model-predicted and experimental parameters obtained using the Langmuir equation pointed to the large effect of salt concentration on the boron adsorption which wasan increase of around 10% and 75% in q max as a result of an increase in salt concentration from 0.02 to 0.06 and 0.12 M respectively. We can ignore the effect ofsalt at very low equilibrium concentration; however, it increases gradually with increasing the equilibrium concentration of boron.
The results of the present study showed that sodium adsorption ratio was low, in low equilibrium concentration related to low boron concentration, but the equilibrium concentration of boron increased with increasing the sodium adsorption ratio.In sodium adsorptionratio of 100, increasing pH increased the adsorption of boron. Boron adsorption was increased with increasing ionic strength; the adsorption rate was muchhigher than the rate of increase in ionic strength.Increasing the ionic strength suppresses the DDL on planar surface and therefore more negative borate ions are able to move close enough to interact with the adsorption sites located on the edge surfaces. Assuming that this phenomenon affects the adsorption of boron, the effect of ionic strength on boron adsorption can be partly dependent on it. Due to the high variability of soil minerals and the differences in their chemical properties, interpretation of the effect of ionic strength on adsorption of boron is not easy, but we can say that it is the sum of the effects of the above-mentioned factors. The positive effect of ionic strength on boron adsorption may suggest that the formation of inner sphere complex is the dominant mechanism for boron adsorption.

Phosphorus deficiency is one of the major problems of calcareous soils in Iran and based on current statistics more than 70 % of all soils in Iran are under critical P levels of 15 mg kg-1 (51). Previous research results show that application of organic matter increases P availability (46) and changes the P distribution between various forms in calcareous soils.The aim of this study was to evaluate the effects of different levels of spent mushroom compost and sugar cane bagasse biochar as agricultural by products or crop residues on availability and phosphorus fractions in a calcareous soil from Karaj (Alborz provience, Iran).
The soil for the experiment was obtained from 0-30 cm depth of Agriculture Faculty farm of Tehran University at Karaj. Some physical and chemical properties were determined using standard methods (table 1). The spent mushroom compost (SMC) was from Malard mushroom factory and Sugarcane bagasse was from a farm in Khozestan. The Biochar (B) was prepared from the raw material heated to 500 degree celcius inside furnace for 3 hours. Some basic properties of SMC and biochar were also determined (table 2). The experiment was conducted in a completely Randomized design with 5 treatments, and 3 time periods with three replications of each treatment. Treatments included 2 biochar levels B1, B2 (15 and 30 Mg ha-1 respectively), 2 spent mushroom compost levels SMC1, SMC2 (20 and 40 Mg ha-1 respectively) and the control treatment (C). For each treatment, 300 grams of air dried soil was used in small pots and after application of materials and mixing they were moist to field capacity and kept inside an incubator at 28-29 ˚C for a period of 120 days. At 14, 60 and 120 days soils were sampled for analysis (by eliminating the pots). Soil properties such as pH, available P, water soluble P and various inorganic P fractions (23) were determined in soil samples. Statistical analysis of the data was done using SAS software and mean comparison using LSD method was also performed.
Results showed that the available P in the control increased significantly (p Based on the results of this experiment application of organic materials of different nature such as spent mushroom compost and sugarcane bagasse biochar to calcareous soils can affect the availability and various forms of phosphorus to the extent that it should be considered as a measure to improve P availability conditions.

Nitrate contamination of water resources is becoming a serious environmental problem worldwide. Application of natural materials to remove nitrate can be considered as the most valuable solution. This study aims to investigate the use of date palm fiber in the production of adsorbent material. Palm fibers were burned at temperatures of 450, 600 and 750 °C in a limited supply of oxygen condition. The produced biochar at temperature of 600 °C was chosen due to its high ability in removal of the nitrate from aqueous solution. Biochar made from these fibers washed with hydrochloric acid 0.5 N and then with distilled water to increase performance. The FTIR method was used to investigate groups of the adsorbent. Additional studies were performed to measure the effects of pH, adsorbent dose, time and temperature on nitrate sorption. The optimal conditions for removal of nitrate were found to be: 0.5 g of adsorbent in 20 ml solution, temperature of 10 °C, 30 min and neutral pH. Under these conditions, the nitrate removal efficiency was over 96 . The adsorption data were explained using the Langmuir and Temkin adsorption isotherms. Kinetic studies showed that the pseudo-second order was the best fitted model to the sorption data.

Phosphorus deficiency is a common disorder for agriculture in calcareous soils. To study the effects of spent mushroom compost (SMC) and sugar cane bagasse biochar (B) on alkaline phosphatase activity and phosphorus availability in three soil types (that is) loam, clay loam, and sandy loam, an incubation experiment was conducted. The treatments included levels of biochar B1 and B2 (15 and 30 ton.ha-1), levels of spent mushroom compost SMC1 and SMC2 (20 and 40 ton.ha-1) and the control (C). After applying treatments in 14, 60, and 120 days, T1, T2, and T3 respectively, available phosphorus and pH were measured and alkaline phosphatase activity at T3 period was also measured. The results indicated that in all soil samples SMC increased phosphatase activity, But biochar was ineffective in sandy loam soil. Average phosphatase activity in control treatment was 2090, 2931 and 2888 µg PNP.g-1Soil. h-1 at sandy loam, loam and clay loam, respectively and was increased to 3034, 3709 and 3533 µg PNP.g-1Soil. h-1 in SMC2 treatment, respectively. Both levels of SMC also caused increase in phosphorus availability, while biochar was less effective on that. SMC2 treatment showed the best effectiveness on increasing phosphorus availability. So that available phosphorus average was increased from19.4, 8.8 and 3.9 mg.Kg-1 in control treatments to 37, 28 and 22 mg.Kg-1 in SMC2 treatment for sandy loam, loam and clay loam soils respectively. Application of SMC reduced soils pH while biochar increased that. Results indicated that SMC has a positive effect on phosphorus availability and improves other properties including pH in calcareous soils.

The potential of activated carbon (a product of Merck) as an adsorbent has been studied for removal of nitrate from some polluted water sources. In line with this purpose, nitrate sorption kinetics and isotherms, as well as the effects of contact time, initial concentration, pH and temperature on nitrate sorption onto activated carbon were investigated. The surface characteristics of activated carbon were also studied, through FTIR and SEM techniques. Two simplified kinetics models, namely: pseudo-first and pseudo-second orders were tested to investigate the sorption mechanisms and while two isotherm models namely Freundlich and Langmuir employed to describe the equilibrium sorption of nitrate onto activated carbon. The results revealed that the amount of nitrate sorption increased with time and reached its maximum after ten minutes past. Maximum nitrate sorption occurred in a neutral pH figure, and with either increase or decrease in the pH level, the amount of sorption being decreased. The amount of nitrate sorption increased with a decrease in temperature, level, the depicting the exothermic nature of sorption. A comparison of the coefficient of determination of the fitted equations indicated that pseudo-second order equation (R2=1.000) was better fitting than pseudo-first order equation (R2=0.839) for description of nitrate sorption data. Sorption isotherm was proper, as described by Langmuier model (R2=0.998) and the maximum sorption parameter equaled 8.93 mg per gr of activated carbon.

Boron (B) is an important plant essential micronutrient whose availability is influenced by many soil factors. Adsorption–desorption processes play a major role in governing the solubility of boron in soil solution and، consequently، its availability to growing plants. To assess the effect of sodium adsorption ratio (SAR) on availability of B، adsorption of B was investigated in a sampled calcareous soils that had low levels of electrical conductivity. Boron adsorption experiments were carried out on the soil in batch systems to determine adsorption isotherms (amount of B adsorbed as a function of equilibrium solution B concentrations). To determine the quantity of adsorbed B، 5 g of soil were shaken for 12 h، in propylene 50 mL tubes، with 20 mL of B solution (0، 2، 5، 8، 10، 15، 20 mg L-1) (as boric acid) at ionic strengths of 0. 12 M (prepared by NaC1، CaC12. 2H2O، MgCl2. 6H2O) at five SAR levels (2، 5، 10، 15، 20). The reaction temperature was 25◦C. The suspension was centrifuged، filtered، and a sample was removed and B was determined by Azomethine-H spectrophotometric method (at a wavelength of 420 nm). Soil B adsorption was calculated by subtracting B in the solution after filtration from the added boron. Langmuir، Freundlich، linear Freundlich isotherms fitted well to the adsorbed data based on R2 and SEE. However، the fit of the Langmuir equation was closer to the experimental data. At different SAR values، the soil exhibited different adsorption behaviors. The effect of SAR on the boron adsorption was greater at high concentrations and the highest adsorption was at SAR 15، except for SAR 20 that had the lowest B adsorption. Effect of sodium adsorption ratio on adsorption of boron may be due to the dissociation of boric acid to borate anion and changes in the thickness of the diffuse double layer.

Changes in chlorophyll florescence is one of the physiological responses of plants to waterlogging stress. Due to easily measured in field and its inexpensive and non-destructive characteristics، it is one of the best ways to assess different genotypes tolerance to stresses. In this experiment، trends of chlorophyll fluorescence index (Fv/Fm) of ‘Satsuma’ mandarin (Citrus unshiu) on seven rootstocks (sour orange، Swingle citromello، Carizo citrange، Troyer citrange، C-35، Smooth flat sevil and Gou tou) were determined in some soils of East Mazandaran. The experiment was conducted as factorial in a randomized complete block design. The results showed that effect of different factors on changes of chlorophyll fluorescence were significant. Soils 7 and 1 had the highest and lowest index، respectively. The effect of different rootstocks on fluorescence index showed that with increasing duration of waterlogging، this index drops increasingly compared to the beginning of waterlogging. Gou tou and Sour orange had the highest and lowest fluorescence during waterlogging، and Swingle، Carizo، Troyer، Smooth and C-35 placed after Gou tou، respectively. In addition، tolerance of rootstocks to waterlogging was different in various soils of this area.

Arsenic (As) toxicity in soil، plant and water is a major global environmental problem. This research was carried out to measure the concentration of arsenic in soil and to compare the arsenic uptake by maize، wheat and rapeseed planted in a natural contaminated calcareous soil. The level of arsenic was identified in 20 naturally polluted soil samples which had been randomly selected in north of Qhorve using concentrated nitric acid، 0. 05 M (NH4) 2SO4، and water extractants. Then greenhouse experiments based on a completely randomized design were used to grow maize، wheat and rapeseed for 120 days in the selected As polluted calcareous soils with three replications. The maximum total As concentration in the selected soils was 3470 mg/kg and the level of As was significantly correlated with the clay، silt and CaCO3 contents. The average levels of concentrated HNO3، 0. 05 M (NH4) 2SO4- and water-extractable As in the soil selected for greenhouse planting were 990 mg/kg، 0. 4 mg/kg and 0. 5 mg/kg، respectively. The levels of As concentration were 7، 15 and 16 mg/kg in the maize، wheat and rapeseed shoots and 51، 102 and 84 mg/kg in their roots، respectively. In addition، the As uptaks by maize، wheat and rapeseed were 0. 728، 0. 350 and 0. 198 mg/pot respectively. The bioaccumulation factors were 0. 006، 0. 015، and 0. 016 and the translocation factors were 0. 129، 0. 148 and 0. 181، in maize، wheat and rapeseed respectively. The As concentration in maize was highly correlated with the water and 0. 05 M (NH4) 2SO4 extractable As compared to concentrated HNO3. Because of higher As bioaccumulation factor، wheat can create higher risk to animals and human than to maize in the agricultural lands of north of Ghorveh.

Use of electrokinetic technique for remediation of contaminated soils has recently been highly attended to, but there are still concerns regarding the effect of this process on soil microbial activity. In this study, changes in concentration of heavy metals extractable through 4N nitric acid, microbial biomass-C, and microbial coefficient, following electrokinetic remediation of a native soil contaminated with heavy metals (zinc, lead, nickel and cadmium) in and at a pilot-scale were evaluated. After 20 days of soil being imposed to a constant voltage gradient of 0.83 Vcm-1 of soil column, the results revealed that over 30 percent of heavy metals close to the anode were removed. However, removal of metals from a distance of 24 cm from cathode about some of the metals (cadmium and lead) is negative. The effect of electrokinetic remediation on biological parameters showed that the level of microbial biomass-C as well as microbial coefficient (following the electrokinetic process) decreased significantly (p< 0.01) with the highest reduction being observed near the cathode where heavy metals had been accumulated. A lack of pH control and its rising trend from anode towards the cathode has most negatively affected the process.

Contamination of soils with heavy metals is often resulted from human activities and phytoremediation is an effective and economic strategy to remove toxic metals from soils. In order to study the effects of different sources of potassium on phytoremediation of heavy metals from a polluted soil، an incubation test and a greenhouse experiment were conducted. The polluted soil was collected from the adjacent areas of Angooran،s Lead and Zinc mining in Zanjan province. In a randomized complete block design with three replication per treatment، four levels of potassium (K) (0، 50، 100 and 200 mg K2O per kilogram of soil as KCl or K2SO4) were added to pots planted with Azargoal variety of sunflower (Helianthus annuus L.). Results showed that K application significantly (p<1%) increased DTPA-extractable (Cadmium) Cd under incubation and the differences between K2SO4 and KCl effects were significant. K2SO4 application significantly decreased soil pH، however KCl increased it. In the greenhouse experiment effects of different treatments on dry matter production of shoot and root، shoot: root ratio (S/R)، Cd concentration، its uptake and translocation factor were significant. In this study the highest amount of Cd uptake (84. 57µgpot-1) was obtained by application of 200 mgkg-1K2O as KCl. Furthermore، cultivation of sunflower decreased concentration of DTPA-extractable Cd. Therefore، this crop is suitable for phytoremediation of Cd. Also phytoremediation efficiency is improved by K fertilizer utilization. More research on this subject under field condition can be very useful and is strongly recommended.