مجله تحقیقات آب و خاک ایران
سال پنجاه و دوم شماره 3 (پیاپی 63، خرداد 1400)

Water scarcity and subsequent social and economic crises have doubled the need to use new interdisciplinary knowledge-based approaches in reforming water resources management structures and policies and implementing water resources plans and projects. In the meantime, recognizing the interrelationships of the social sciences and their water resources systems has become a problem that its solution help us to correct existing dysfunctional structures. Therefore, the main purpose of this study is to prove the interrelationship of some social parameters and water resources on a continental scale with the use of software modeling tools. In this study, per capita data on renewable water resources and social parameters including the ratio of rural population to urban population, population density, number of Internet users and education index on an annual scale are considered. The statistical period of the data was 13 years (2005-2007) and this study was performed for 42 countries in Asia whose per capita water resources were declining. Then, using soft copmuting methods such as Artificial Neural Network (ANN), Decision Tree (M5) and Adaptive Fuzzy-neural Inference System (ANFIS), the interrelationship between per capita water resources and social parameters was modeled. Modeling results were evaluated by the criteria of determination coefficient (R2), root mean square error (RMSE) and mean absolute error (MAE) values. Finally, the results indicate the superior performance of ANFIS method compared to the other two models in evaluating the interaction of per capita water resources and social parameters. Also, after the ANFIS model, the M5 and ANN models had better performance, respectively.

In this research, the yield and evapotranspiration of maize were investigated under water stress at different growth stages. The experiment was performed as factorial in a randomized complete block design. Treatments included m water stress at growth stages of 4-leaf, 12-leaf, flowering, grains doughing and a control treatment under full irrigation. Daily plant evapotranspiration was measured based on soil water balance in the root zone. The total amounts of evapotranspiration in the control and the proposed treatments (water stress at growth stages of 4-leaf, 12-leaf, flowering, grains doughing) were estimated to be 462, 401, 322.5, 304.5 and 355 mm, respectively. Similarly, the dry biomass of maize was equal to 15025, 14422, 11384, 7746 and 13416 (kg. ha-1), respectively. Descending amounts of evapotranspiration and yield were correspond to control, 4-leaf, doughing, 12-leaf and flowering treatments, respectively. The reason was the sensitivity and different need of plant to transpiration, at different growth stages. To evaluate the yield response to maize evapotranspiration, the value of  coefficient in the mentioned growth stages was determined to be 0.3, 0.8, 1.42 and 0.46, respectively. At the flowering stage, the value of  coefficient was higher than one, which indicates that the yield of maize is reduced more than the evapotranspiration. The amount of water productivity in the control and stress treatments were calculated to be 3.25, 3.6, 3.53, 2.54 and 3.78 (kg.m-3), respectively. The highest to lowest values were corresponded to seeds doughing, 4-leaf, 12-leaf, control and flowering treatments, respectively. The results showed that the full irrigated plant (control treatment) was not a guarantee to increase the water productivity. Rather, by refusing to achieve the maximum yield and accepting the low reduction in yield, water productivity can be increased. Under these conditions, selecting the suitable plant growth stage for low irrigation was also important.

Submerged weirs are short-height structures that are completely beneath the water surface and are constructed to improve shipping conditions, create aquatic habitats, control the movement of bends, etc. The purpose of this study was to evaluate the patterns of erosion and sedimentation at a 90o sharp bend. To achieve this goal, a series of weirs with the relative heights of 30% and 70% and crest slopes of 0 and 7% were constructed on the outer wall of the bend. The angle, length, and distance between weirs were kept constant. The results showed that bendway weirs with a relative height of 70% and a flat crest slope had the best performance in protecting the bed near the outer bend wall. With the construction of these structures in the bend, 7% of sedimentation was done near the outer wall at a cross-section corresponding to the maximum scour location in the unstructured state. Changes in the height and crest slope of the bendway weir did not have a significant effect on reducing the maximum relative height of point-bar, and only at Froude number of 0.43 the average maximum relative point-bar height decreased by 10%. Moreover, with increasing the height and crest slope of the weirs, the maximum relative scours depth at the nose of the third weir increased by 11% and decreased by 6%, respectively.

Soil erosion is a global problem that threatens water and soil resources and land use change is one of the important factors in soil erosion. The purpose of this study is to evaluate the effect of land use change on soil erosion and sediment production in Ramhormoz basin in Khuzestan province. Landsat ETM+ (2002) and OLI (2019) images were used for this purpose. First, satellite images were classified using the Object Oriented Method (SVM) algorithm and the land use changes were studied during the years 2019-2002. Then the amount of soil erosion was calculated using the RUSLE model and the amount of sediment load in the area was estimated. The results showed that the residential areas, barren and rainfed cultivated lands increased by 3520.86, 7041.72 and 5281.29 hectares, respectively, and water bodies, pastures and irrigated lands have lost 1760, 43.02, 02.02. 12323 and 1760/43 hectars of their lands, respectively. The result of these changes in areas has been a decrease in natural soil cover and an increase in erosion in the region. Considering the landing limit of about one ton per hectare per year, it was found that the amount of erosion have been more than the acceptable level in 43.24 and 64.99% of the area in years 2002 and 2019, respectively. The results of calculations of sediment delivery ratio methods also showed that the rate of sediment delivery ratio varies from 0.07 to 0.28 and the maximum sediment load varies from 0.18 to 0.63 tons per hectare per year. Therefore, the results of this study clarify the need to address the issue of soil erosion in the region and to provide management solutions.

Soil salinity is a major abiotic constraint affecting crop yield and quality of ornamental plants. The current study aimed to investigate the melatonin and ascorbic acid regulator on the morphological and physiological characteristics of miniature roses under salinity stress, in the research greenhouse of Agriculture and Natural Resources Campus, University of Tehran, located in Karaj, on biennial cuttings of miniature roses, in plastic pots with a diameter of 14 cm containing cocopeat and perlite (1: 1), in the randomized complete block design with four replications, in the spring of 2018. The studied factors included foliar application of melatonin (at four concentrations of 0, 1, 10, and 100 μM) and ascorbic acid (at three concentrations of 0.5, 1.5, and 3 mM) and combined treatment containing two levels of melatonin 1 μM × ascorbic acid 0.5 mM and melatonin 1 μM × ascorbic acid 1.5 mM and salinity stress at three levels of zero, four and eight dS/m. The results showed that the salinity stress generally reduced morphological characteristics; in this study, the most effective treatment in the foliar application was observed with 3 mM ascorbic acid treatment, which increased the number of flowers and branch height by 36% and 86%, respectively, compared to the control. Foliar application of melatonin 100 μM showed the highest effect on the concentration of nitrogen and potassium equal to 43% and 11% as compared to the control, respectively. Accumulation of soluble sugars during salinity stress conserving osmotic potential and reducing dehydration, and the leaf soluble sugar increased by 11% as compared to the control and proline was observed in foliar application with 1 μM melatonin treatment. The results of this study showed that the ability of this antioxidant (Ascorbic acid 3 mM) can be used to improve the growth and development of miniature roses under salinity stress.

Studying the response of different plant cultivars to salinity stress and introducing the resistant cultivars is one of the most important strategies to increase cucumber yield under salinity stress. This study was done to investigate the effect of irrigation with different levels of salinity on growth and physiological characteristics of several cucumber cultivars. For this purpose, a factorial experiment with two factors including cultivar (Keyhan, 485 and Nahid 484) and salinity (0.5, 3.1 and 6.2 dS m-1), each at three replications was conducted. The results showed that salinity stress affected the plant growth and photosynthetic pigment content. At the highest salinity level as compared to the control, the chlorophyll a in Keyhan, Nahid 484 and 485 cultivars decreased by 47, 21 and 19%, respectively, while the total chlorophyll was reduced in Keyhan cultivar by 34% and in the other two cultivars by 22%. Under salinity stress, the highest amount of carotenoids was observed in Nahid 484 and 485. The results also indicated that with increasing salinity level to 6.2 dSm-1, the plant height in Keyhan, Nahid 485 and Nahid 484 cultivars decreased by 30, 23 and 11%, respectively. In addition, the percentage of leaf fall at the highest salinity level was observed in Keyhan cultivar with a 28% reduction as compared to the control. Cultivar 485 showed the highest reduction of root dry weight by 40%. In general, different cultivars showed different responses to salinity stress. Among the cultivars, Nahid 484 showed the hegighest resistance in response to salinity stress, therefore it can be introduced as a tolerance cultivar in terms of salinity stress.

Climate is an important influential element in the field of environment; So that the optimal management of aquatic and terrestrial ecosystems is not possible without serious attention to climatic conditions. In recent decades, water bloom of aquatic ecosystems has grown significantly. This risen growth is due to natural changes in climate patterns and distribution mechanisms of species, affected by environmental factors. The Goals of this study, as a retrospective research, are; a) evaluation of changes in the dominant pattern of phytoplankton communities in Aras Dam Lake in 2008 and 2013, b) investigation of the impact of meteorological, physical and chemical factors on phytoplankton population growth in the study area. Data sampling was carried out seasonally in three positions, namely Dam entrance, middle of lake and Dam output. At each gaging position, data were collected to identify and count phytoplankton and to analyze several water chemical factors. Satellite data were received from the MODIS sensor and chlorophyll a images were obtained. The highest levels of chlorophyll a in summer of 2008 and 2013 were 12.71 and 10 (mg/m3), respectively. Results showed that the abundance of phytoplankton had a high correlation with the concentration of chlorophyll. In summer, the high temperatures and pH affect bloom of Cyanobacterial communities. Usually, Cyanobacterial blooms were related to high values of temperature, pH and high concentration of the dissolved oxygen in summer. The results of principal component analysis and multiple regression showed that the air temperature is the most important factor in chlorophyll changes. The correlation coefficient between chlorophyll and air temperature was calculated to be 0.72. Change in the dominant pattern of phytoplankton communities towards Cyanobacterial pattern was observed in Aras Dam Lake, showing domination of Cyanophyta branch in all seasons of 2008 compared to 2013. This result may be caused by changes in the temperature and precipitation patterns over the study area.

Since the majority of water resources is used for agricultural purposes, irrigation and drainage networks become important. Moreover, these networks are threatened by various natural and unnatural hazards that each one can affect the performance of the network. This research seeks to develop a risk analysis model of agricultural water distribution systems with the help of hybrid Bayesian networks. The proposed hybrid Bayesian model evaluates the risk of agricultural water distribution system and its components with the following inputs: inflow of water distribution system and its fluctuation, and the demand of water. The hazards which threat the system are identified and the model nodes are determined according to these risks and the system components. This model was investigated on the distribution of Roodasht irrigation network located in Isfahan, which is under the threat of improper performance of the ditch-riders and operational losses. The average risk value of the distribution system was 14.8% and the risk of components was calculated in the range of 0.01-49.2%. The hybrid Bayesian network model shows a good accuracy and performance in training and test sets with root mean square error of 0.07% and 0.08%, and coefficient of determination of 0.65 and 0.63, respectively. The proposed model helps operators and decision-makers to be aware of the causes and potential failures of the system’s components. This can lead to better planning for the allocation of irrigation water based on the anticipated risks in the occurrence of various hazards.

Simultaneous application of biochar and chemical fertilizers has been shown to be a new sustainable and environmental friendly technology for the improvement of soil fertility, nutrient use efficiency and rice crop yield. However, simultaneous application of biochar and zinc have been rarely studied. Therefore, the current field study was conducted to investigate the effects of rice husk biochar and Zn-fertilizer applications on rice yield and the most important chemical properties of soils through factorial in randomized complete block design with three replications at farm stations of rice research institute of Iran, Rasht and Tonekabon in 2019. The experimental factors were biochar at three levels (0, 20 and 40 tha-1) and zinc at three levels (0, 10 and 20 kg ha-1). The highest plant height (144/33 cm), filled grain per panicle (81.65), 1000 grain weight (32.37 g) and grain yield (4112 kg ha-1) were recorded at 40 tha-1 biochar treatment. Moreover, the maximum grain yield with average of 4220 kg ha-1 was observed at 20 kg ha-1 Zn sulfate treatment (13% more than the control). The application of 40 tha-1 biochar of rice husks and 20 kg ha-1 Zn significantly increased the available P, K and Zn by about 2 times, 43.15% and 3 times, respectively.

Groundwater level prediction is an essential priority for planning and managing groundwater resources. This study aimed to compare the accuracy of the Neuro-Fuzzy Adaptive Inference System (ANFIS) model with the ANFIS model combined with particle swarm optimization algorithm (ANFIS+PSO) in predicting the monthly groundwater level of Golpayegan aquifer during 2002-2019. For this purpose, monthly data on rainfall, temperature, pan evaporation in the selected meteorological stations, discharge volume of exploitation wells and groundwater level of observation wells have been used. After spatial and temporal analysis, four observation wells with two input data structures (S1 and S2) were selected to predict the groundwater level. The results of trend and homogeneity tests show a 99% significance of groundwater level changes in the selected observation wells 4, 8, 19 and 20 with a sudden drop of 22, 17, 27 and 2 meters before and after June, September, July and August 2010, respectively. The highest and the lowest accuracy of groundwater level prediction is related to observation wells 20 and 4 with root mean square error values (RMSE) of 2.37 and 0.21 m, respectively, related to ANFIS_S1 and ANFIS + PSO_S2 models. Generally, the results of this study indicate that the selection of appropriate structure of input data is more effective than the combination of two models (ANFIS and PSO) in increasing the accuracy of groundwater level prediction. So, that the optimal structure of input data and the combination of optimized algorithm model have increased the accuracy of groundwater level prediction, 44% and 25%,  respectively.

Facing to drought in recent years has lead to focus on promoting the use of localized irrigation in the country. Due to the shortage of available water resources, farmers have also realized the need to use a drip irrigation system. Monitoring and evaluation of existing and operating systems is of particular importance that can prevent the waste of capital and achieve the main goals of the application of pressurized irrigation systems. Date is one of the garden products that play an important role in food security and national economy. Hence the purpose of this research is technical and hydraulic evaluation of the performance of localized irrigation system (bubbler) on palm trees located in Bastak city in Hormozgan province and also comparing water productivity of this method with the basin irrigation system, which is common in this area. For this purpose, two farms were selected and evaluation parameters were determinrd by measuring the flow rate and pressure of the bubblers in two stages. According to the results of this study, the potential application efficiency of low quarter (PELQ) and actual efficiency application of low quarter (AELQ), which represent the overall performance of the localized irrigation system (bubbler), were 29.21% and 32.44% on March 2019, and 32.64% and 36.26% on June 2019, respectively. Therefore, the performance of proposed irrigation system was evaluated to be in a poor condition. By training the operator to wash the filtration system properly and timely and to contorol the semi-main pipe valves adjustment, the performance of the localized irrigation system can improve. Water productivity of the date cultivar Khanizi was 0.18 kg/m3 for the garden irrigated with basin surface irrigation method. However, it was 0.33 kg/m3 for the garden irrigated with bubbler system. Therefore, the bubbler irrigation system had a higher water efficiency in comparison to the surface irrigation. The results showed due to lack of training to operator, absence of design engineer at the project site, lack of accurate information from the project site and also the lack of proper supervision over the implementation of the drip irrigation system, the performance of the system has not been at an acceptable level.

Management and planning in the field of water resources in different seasons, especially in spring, is very vital for exploitation in the agricultural, industrial and drinking sectors in arid and semi-arid regions of the world, especially Iran. Climate Teleconnection Indices (CTI) as large-scale indices can be important in hydrological behavior at the basin scale. In this study, the relationship between these indices and spring rainfall in the basins of Iran was investigated and the possibility of using them as predictor variables was identified. For this purpose, the correlation of 40 CTI in time delays of 6 to 1 month with spring rainfall was investigated. The results showed that the percentage of stations that have a significant correlation with spring precipitation, varies depending on the location of the basin, but in general, the indicators related to ENSO and SSTs have the most frequent significant correlations with spring rainfall in the northern half, northwest, northeast and sometimes southwest springs. These indicators in the Caspian Sea basin with a delay of 3 to 6 months, Persian Gulf-Oman Sea with a delay of 1 to 3 months, Lake Urmia with a delay of 3 months, Central Plateau with a delay of 1 to 4 months, Eastern border with a delay of 1 and 6 months, and Qarahqom basin with a delay of 1 and 3 months have the highest amount. In general, it can be said that the spring rainfall in many stations located in the watersheds of the northern half of Iran have a significant correlation with the CTI, but in the southern, the central plateau and the eastern part have the lowest correlation, which is due to the low rainfall in this season in the southern regions. The results showed that the efficiency of predicting spring precipitation by MLP model is better than MLR model.

Sustainable agriculture at arid and semi-arid areas depends on optimized usage of fresh water resources. Evaporation from soil surface and deep percolation categorized as unuseful losses at irrigation, so their reduction could increase the root water uptake efficiency and yield production. Subsurface drip irrigation could provide this situation. Proper depth for installing dripper is the place that reduces soil surface evaporation and deep percolation. The objective of this study was to investigate the effects of various dripper installation depth on soil water content distribution and root water uptake and to choose the proper depth. For this purpose, HYDRUS-2D software was used to investigate the effect of three factors on non-beneficial losses and consumed water in drip irrigation, numerically. These factors were soil texture (loam, clay loam and sandy loam), installation depth (0, 10, 15 and 20 Cm) and dripper discharge (1, 2, 4 and 8 l.h-1). The results showed, although increasing the installation depth could reduce cumulative evaporation up to 40%, but the best installation depth was 15 Cm with discharge rate of 1 l.h-1, according to the amount of deep percolation and consumed water. The effect of soil texture was more than the effect of installation depth on the amount of irrigation water, so that the amount of irrigation water in 2 l.h-1 discharge rate was 2.9, 3.1 and 4.6 m3.m-1 for loam, clay loam and sandy loam soil texture, respectively. Also, for clay loam texture, dripper discharge had the highest effect on root water uptake and the installation depth had the lowest effect on soil surface evaporation.

Optimization of monitoring network is a decision-making process through which, the best combination of existing stations is selected. Regarding the economic considerations and reducing monitoring costs, optimization approach in this study is to reduce the number of surface water quality monitoring stations in Dez basin in Lorestan province. In this regard, using an algorithm based on the principle of maximum entropy and water quality index of SO44, Cl, HCO3, K, Na, Ca, Mg, pH, TH, SAR, EC and TDS parameters, the optimization procedure was done for 18 existing monitoring stations during the statistical period of 1387-1396 (2008-2017). First, the average rank of each station in the mentioned 10 statistical years was obtained, then some models were proposed for the network entropy according to the number of stations and year. After fitting the best model, the results showed that based on SO4, Cl, HCO3, K, Na, Ca, Mg, pH, TH, TD, SAR and EC parameters, the number of sufficient stations as surface water quality monitoring network in the study area were 9, 9, 7, 11, 11, 11, 10, 7, 10, 10, 10, and 11, respectively. In order to validate the proposed network, by comparing the entropy of the proposed network with the entropy of random networks with the number of stations based on the 12 mentioned parameters in each year, the efficiency of the selected network was confirmed. Also, among the 12 evaluated quality indicators, chloride showed the highest entropy of weight. Therefore, chloride had the maximum entropy and was selected as the superior index.

Continuous monitoring of agricultural lands is imperative for managing water and soil resources in a watershed, due to its impact on ecosystem health and food security. Global Land Cover (GLC) maps can be used as a proxy for local and regional land use maps because of their availability, variety, and ease of use without complex processing. This study investigates the performance of three GLC products including MCD12Q1 LC, CGLS LC, and CCI LC against a reference land use/ land cover map of the year 2015 in the LUB. First, identical classes between the reference map and the GLC maps were determined based on the main land use/ land cover classes of the reference map of 2015 (rangeland, agricultural land, water, built-up areas, and bare land). To do so, different classes were merged accordingly to match the classes of the reference map. Subsequently, performance (Area and spatial consistency, and classification accuracy) of the GLC products was evaluated based on ground truth points. Results showed that MCD12Q1 LC and CGLS LC outperformed CCI LC in providing an overview of the surface cover of the LUB with 74% and 86% overall accuracy, respectively. Moreover, MCD12Q1 LC and CGLS LC had an acceptable performance in classifying rangeland and agriculture land as the dominant land cover types in the LUB with 81% and 92% classification accuracy, respectively. The CGLS LC can also be used to continuously monitor agriculture areas in practical applications to examine the overall trend of urbanization and agricultural development. Another important finding is that the GLC product with higher spatial resolution does not necessarily provide better classification accuracy for all types of covers. This study can also be used as a methodological reference in the performance evaluation of the GLC products at different scales and other parts of the country.

Models to explain water characteristic curve and liquid distribution in partially saturated porous media are abundant, mostly based on the “bundle of cylindrical capillaries” (BCC) representation of pore-space geometry. The assumptions in the BCC model are that 1- certain pore sizes are completely filled by liquid whereas larger pores are completely empty at a given saturation level and 2- the surface area and adsorbed liquid films are ignored. Tuller-Or (TO) model is among the few physical-based models that considers both the capillary and adsorption phenomena via introducing a new pore space geometry with angular central pores attached to slit-shape pores. However, the original TO model fails to describe experimental data in the intermediate saturation range because of the limited flexibility of the probability distribution invested for describing the pore size space. In this study a new enhanced form of TO model was proposed which is based on the numerical solution and is capable of using Gamma distribution for pore size distribution with arbitrary shape factor and |Weibull distribution. The results obtained from the optimized model for soils with different textures showed significant improvement compared to the original model, especially in mid-range saturations whereas the original TO model shows low accuracy. The new enhanced version also includes a global search algorithm for fitting the TO model that provides unique set of fitting parameters that are independent of initial guesses.

Fluoride is widely used in industries and release to the environment via their effluents. One method of fluoride removal is adsorption using inexpensive adsorbents. The purpose of this sturdy was to compare the efficiency of pistachio pulp biochar in fluoride removal from water.In this study, pistachio pulp biochar was produced through pyrolysis at 600 °C for 3 hours with a heating rate of 25 °C min-1. To determine the adsorption isotherms, 20 mL of fluoride solution with different concentrations (zero, 3, 6 and 9 mg L-1) of NaF salt was added to 0.5 g biochar and then the samples were shaken for 24 hours and finally the adsorption data were fitted to Langmuir, Freundlich and Temkin isotherm models. In order to investigate the effect of time on fluoride adsorption, 20 ml of fluoride solution with initial concentrations of  3, 6 and 9 mg L-1 was added to 0.5 g biochar and samples were shaken for different times (15, 30 , 45, 60, 90,75, 105, 120, 135, 165, 180, 195, 210, 225 and 240 minutes). Then, the concentration of Fluoride was measured. The results showed with increasing the retention time, the percentage of fluoride adsorption by biochar increased and after 240 minutes for concentrations of 3, 6 and 9 mg L-1 were obtained 70.89, 63.05 and 54.66, respectively. The pseudo-first-order and pseudo-second-order models were introduced as the best kinetic models of fluoride adsorption compared to other models. The results of fitting data to the Langmuir, Freundlich and Temkin isotherm models showed that Langmuir model provides a better description of the fluoride adsorption process by biochar. The maximum fluoride adsorption (306 mg kg-1) was obtained by biochar from the Langmuir model.

One of the remediation methods for soil contaminated with heavy metals is to use hyperaccumolator plants which is known as phytoremediation. The use of a new generation of biodegradable chelate agents is increasing the efficiency of phytoremediation and preventing environmental pollution. Vetiver is a good option for using the new generation of chelators. The aim of this study was to investigate the effect of different levels of biodegradable chelates EDDS and MGDA at four levels (0, 1, 2 and 4 mmol per kg of soil) on increasing copper extraction at three levels of copper pollution (100, 200 and 400 mg kg-1 of soil) which was carried out by Vetiver grass (Chyrsopogon zizanioides L.). The amount of copper uptake by vetiver in the presence of 4 mmol EDDS treatments at 100, 200 and 400 ppm levels of copper contamination were respectively 8281, 10125 and 10423 µg plant-1 after 120 days, which were 51, 84 and 89 percent more than the one in control treatment (absence of chelate). The amount of copper uptake in 4 mmol MGDA treatment at the aformentioed levels were 5679, 7688 and 8831 µg plant-1, respectively, which they were increased 19, 61 and 85 percent compared to the control treatment. Application of EDDS chelate increased the level of extractable copper with DTPA. The maximum amount of extractable copper at 4 mmol EDDS and MGDA and 400 ppm-copper treatment was 27.5 and 16.7% more than the one in control treatment, respectively. The mean values of bioconcentration factor (BCF) in 4 mmol of EDDS and MGDA were 0.51 and 0.37 respectively, and the mean value of translocation factor (TF) was 0.19. The results of this study showed that vetiver has a special ability to remediate copper-contaminated soils and 4 mmol EDDS per kg of soil treatment intensifies the uptake of copper in the roots. Consequently, vetiver grass could be considered as a candidate species for phytostabilization of Cu pollution, which not only protect the soil but also reduces the risk of food chain pollution and EDDS is introduced as a suitable biodegradable chelate that enhances phytorermediation of copper by vetiver.

Degradation of forest habitats and change of land cover can have significant effects on the variability of soil quality indicators. In the present study, different soil characteristics in forest habitat (almost intact) dominated by Zelkova carpinifolia, rangeland cover dominated by Festuca ovina and single trees of Zelkova carpinifolia and Ulmus minor, rangeland cover dominated by Dactylis glomerata and Thymus transcaspicus and rangeland cover dominated by Stachys byzantina in Zanus region of Kojoor district of Mazandaran province were examined. For this purpose, 36 soil samples (including 12 samples at spring, summer and autumn) were taken from each land cover from a depth of 0-10 cm and transferred to the laboratory. The results indicating the variability of most of the studied soil characteristics in different seasons of the year under different land covers. Based on the principal component analysis (PCA), higher amounts of clay, macro and micro aggregate, pH, total nitrogen, nitrogen in macro and micro aggregate have lead to increasing soil biochemical and microbial activities (i.e. ammonium, nitrate, carbon microbial ratio and nitrogen mineralization) under Zelkova and Festuca covers. While Stachys and Dactylis cover with higher amounts of sand, carbon in macro and micro-aggregate had the lowest soil biochemical and microbial activities. According to the results of this study, it can be claimed that the presence of tree cover (i.e. Zelkova carpinifolia and Ulmus minor) in habitats can provide better conditions for soil functions, which can be considered by managers to rehabilitate degraded lands.

One of the most important environmental hazards that is rising drastically in IRAN in the last decade is wind erosion causing the spread of soil particles. The present study aims to evaluate the effect of soil surface moisture on the wind erosion threshold velocity in three supercritical centers of dust, located in the regions of south and southeast of Khuzestan province. For this purpose, 11 soil samples from the selected regions were collected. The soil samples were prepared in terms of moisture contents (air-dry, 4, 7, and 9%). Then they were tested in a wind tunnel based on a completely randomized design. The results of comparing the mean values of wind erosion threshold velocity using Duncan method at a probability level of 5% confirmed that the effect of moisture on the erosion threshold velocity is significant for all samples. In addition, the two parameters of moisture and erosion threshold velocity was strongly correlated in all soil samples, so that with increasing moisture levels, the wind erosion threshold velocity also increased. The findings also confirmed that the amount of increase in velocity is different depending on the levels of moisture, indicating that increasing the moisture content from air-dry to 4% level yielded the largest change in threshold velocity, which could have a substantial effect in controlling the erosion phenomenon in the study regions.