فصلنامه پژوهش های فرسایش محیطی
سال سیزدهم شماره 3 (پیاپی 51، پاییز 1402)

Considering that there are no accessible works and evidence regarding the nature and extent of environmental changes caused by climate changes in the future, it is possible to reconstruct past climatic events through the archives of lake sediments left over from these climatic periods. Reconstruction of the past climate is a guide to understanding what can be expected in the future under similar conditions. According to the geographical location of Iran, climatic and environmental changes are a suitable platform for paleoclimatological research in order to reconstruct ancient environments and their shaping factors. Climatic conditions and their changes have played a significant role in the formation of the first human civilizations. The rise and fall of some ancient civilizations have been directly related to climatic changes. There is no comprehensive information about the conditions of Iran during the Holocene. Although the Middle East has always been an interesting place for researchers because it was the first place for agriculture and domestication of animals, compared to other places, this region has been less studied. However, the studies conducted on the climatic changes of the Iranian Plateau during the Holocene present evidence that shows that the climate of this land has changed intermittently, which has played an important role in the creation and destruction of ancient civilizations and their migrations.

In order to reveal the changes in climatic conditions in the past and present, this research investigates the paleoclimate in this region through the evaluation of laboratory analyses (i.e., granulometry, elemental analysis and its indices) on sedimentary data and the interpretation of paleoclimate conditions. The method of this research is a field, laboratory and analytical method conducted based on collecting data from the surface of the earth, performing the analysis, analyzing them and examining the influencing factors by integrating the results. The research data consists of library data and written sources, image data, sediment data collected during the field visit of the region and laboratory analyses.

  According to the study of sedimentary cores in Jazmurian playa which were taken from the northern margin, the sedimentary type of the samples of the first core is generally closer to the mountains than the sandstone type, and in some samples, it is sandstone with a little Gravel is formed, and the samples of the second borehole, which is closer to the center of the playa, are generally composed of sandy silt. The process of sandification in these sediments is the same from the surface to the depth, and in the middle facies of the sedimentary core, it shows a periodic increase and again follows a decreasing trend, which indicates a wetter period compared to the previous period. It is self-dimensional and this facet is clear in both cores. Of course, it should be mentioned that the first core, because 13 facies are investigated, shows more fluctuations than the second core, which has 6 layers at a depth of 200 cm. Fluctuations in facies have become less apparent. The S/M index shows that in core number 1, the sediments from the middle surface of the core are muddy and it shows calmer environmental conditions, it becomes a little sandy in the middle, and then up to a depth of 180 cm, the trend is muddy again, and after that, the conditions are more humid and the S/M index is sandy. In core number 2, the range of changes is less, but almost in the middle of the core and at a depth of 170 cm, sands flow, which indicates a humid environment, similar to core number 1. The elemental analysis of ICP and climatic indicators in sedimentary cores determine the fluctuations of humidity, dryness and ambient temperature in different sequences in the Jazmurian region. For example, the high level of Mn indicates a reductive environment, while the calcium element, like sodium, indicates the dryness of the environment. Also, the two elements of manganese and magnesium indicate regeneration conditions, more precipitation, more water entering and less evaporation. The increase in Al values in the sediments indicates an increase as a result of more debris entering the environment.

The results show that these elements and indicators well determine the paleoclimate fluctuations in the Jazmurian sedimentary environment in the sedimentary cores collected from the region during the Holocene period and in general, the range of climatic fluctuations in Jazmurian is very high. Also, the grain size and sediment indicators have been very useful in the interpretation of the sedimentary environment in the Jazmurian region and they have clarified the ancient climatic conditions in this sedimentary environment.

The natural hazards are impossible to avoid, and infrastructure elements and communities cannot be made totally invulnerable. The only viable solution is the complex risk analysis and subsequent development of combination of mitigation and adaptation strategies Floods are the most common natural disaster type worldwide. Between 1995 and 2015, 2.3 billion people were affected by floods, con siderably more than any other type of natural disaster event. In general, the Givi Chai basin includes two cities, Khalkhal and Kausar. In recent years, floods have caused damage to gardens and facilities due to spring and summer rains to the extent that the villages that are located under the Sangur Chai basin because of being located at the source of the rivers and mainly in the course of the rivers are affected by floods; also in the whole basin due to droughts and the destruction of vegetation and the increase of man-made areas, the amount of impermeability has increased. Considering that Khalkhal is a mountainous area and is one of the areas sensitive to landslides in Azariaijan region, heavy rainfall and floods can wash away the slopes of this area.

The Givi Chai basin in the south of Ardabil province with an area of 1554 square kilometers is one of the 3rd degree basins of Sefidroud, which is located in the geographical coordinates of 48°4' E longitude to 48°38' E longitude 37°27' N latitude 37°55' N latitude. In order to achieve the goals of this research, firstly, the theoretical foundations and the works done in connection with flood zoning of basins in Iran and outside Iran were examined. Many variables are effective in the flood of basins. In this research, from the 1.100000 geological map, the slope maps were obtained using the digital height model map; the land use map was obtained through the classification of the  Maximum Likelihood  in ENVI software. In addition, using the digital model of the height of resolution  to extract, a drainage density map was prepared using the Line density tool. In this research, using the FAHP fuzzy hierarchical analysis model, Expert CHOISE software was used for weighting the layers, and finally, a map was prepared in the Arc GIS environment using gamma 0.5, 0.7 and 0.9The basin was flooded.

After preparing the effective factors for zoning the flood potential of the basin, the gamma fuzzy operators of 0.5, 0.7 and 0.9 were used. 37 floods have occurred in the studied basin from 1365 to 1399 in different parts and villages, which caused the destruction of rural houses, gardens, agricultural lands and livestock. In order to determine the final flood map, points were randomly selected on the zoning map, then the correlation level was obtained based on the specified points with each of the criteria in the ARC GIS software. Based on the results obtained from the correlation, the highest correlation level is related to gamma 0.9. Vegetation has the highest correlation of 0.5 and lithology has the lowest correlation with gamma of 0.9 and 0.062. Also, the last flood occurred in the studied basin in the villages of Mustafa Lo, Bolokan, Morestan and Khoda Qeshlagi, which are located in the high-risk zone according to the final flood zoning map.

In this research, using the FAHP model, flood potential zoning has been evaluated in Givi Chai basin. The data of height, slope, lithology, precipitation, vegetation, soil hydrology, distance from the river, drainage density and land use have been used for flood zoning. After preparing the zoning map, the studied basin was divided into five classes based on the severity of flooding: very low, low, medium, high, very high. The results obtained from the flood zoning of Givi Chai basin have shown that the largest area of the studied basin, which is 0.9 gamma scale, has the highest correlation. The strata with very low, low and medium potential, gamma 0.5  0.7, were showed. cover the area of Givi Chai basin. Also, the final flood map of the basin was validated with the villages that have been damaged by floods in recent years. The areas which are more exposed to floods are in the regions that have very low permeability in terms of lithology and hydrology of the soil and in the areas where the vegetation cover as less as.

Heavy metals are elements that have an atomic mass of more than 55.8 g/mol; these elements have little biodegradability, but their ability to bioaccumulate is very high, and when their concentration exceeds the threshold, they threaten the health of the environment with the risk of toxicity and pollution. West Bandar Abbas industrial area consists of several industrial complexes located less than 5 km from Shahid Rajaei wharf, and the high-traffic transport axis passes through these industries. The concentration of these industries and traffic of the transport road have caused severe pollution of the environment and ecosystems in this area, but the level of pollution in various aspects remains unknown. Although studies have been conducted on air pollution or environmental assessment, the assessment of soil pollution, heavy metals and their effects on the plants of the region, which are biological markers, have not been investigated since it is possible to reveal the level of environmental pollution by evaluating the level of pollution in plants. Therefore, the main approach of the current research is to evaluate the level of environmental pollution in the industrial area of west of Bandar Abbas by examining heavy metals in the soil and leaves of Acacia in the area, and also investigating the reaction of Acacia, which are native to this area, against pollution.

The experiment was implemented in the RCBD plan. From each location, 10 soil samples (replicates) were taken at a depth of 0 to 10 cm and placed in an envelope and labeled. Soil samples were transferred to Bandar Abbas soil laboratory to measure the concentration of heavy metals including lead (Pb), cadmium (Cd), zinc (Zn), copper (Cu), chromium (Cr) and nickel (Ni), which were evaluated by Igeo, CF, PLI, BCF, MAI and RI indexes. Biochemical reactions of Acacia, including its photosynthetic pigments, proline, ascorbic acid and relative leaf water against pollution were measured. Finally, APTI was obtained for Acacia.

In this study, the level of heavy metal pollution caused by industries in the target area was evaluated by inspecting some pollution indicators. According to the Igeo index, the areas close to the industries and the area of industrial factories and Bandar Abbas oil refinery are the most polluted areas and contain much higher heavy metals than the standard heavy metals in the soil. Evaluation of Igeo for zinc and copper metals is low and it is in the class of non-pollution to moderate pollution, but for cadmium, lead, chromium and nickel in the measured points, it is mostly moderate to very severe pollution, and in the places close to the industries, mainly for all metals, the level of pollution is moderate to severe. Away from the industrial factories, the concentration of pollutants and the risk of pollution decrease. The CF is also high for cadmium, lead, chromium and nickel, and the pollution level is significant, moderate and severe. The PLI in this study showed that the points near Shahid Rajaei industries and wharf have high pollution loads, but with the distance from the industries, the numerical value of this index decreases and the pollution load also decreases. In this study, the biochemical reaction of Acacia against heavy metal contamination was also measured. Pollution has an effect on the content of photosynthetic pigments of Acacia in the industrial area of west of Bandar Abbas to the extent that the amount of chlorophyll a, b and total chlorophyll in the polluted areas and near the industries compared to the clean and control areas and the areas far from the industries showed a significant decrease at 99% level. The results of this research also indicated that pollution can reduce photosynthesis in plants by reducing pigments. In addition, it was found that in Acacia under the stress of heavy metal pollution, the concentration of ascorbic acid and proline differed by 99% and increased compared to the control condition. This increase helps the Acacia to continue its physiology and mechanism and survive under the stress of pollution. Furthermore, APTI was calculated in the Acacia in the studied locations and the results showed that in the highly polluted sites in Shahid Rajaei Wharf, Bandar Abbas Oil Refinery and Industrial Area, the concentration of heavy metals in the soil as well as the air pollution is very high. APTI is reduced and reaches 7; however, in the eastern slope of Salt Dome, Shahid Bahonar Wharf and Point Shahid, the APTI of Acacia plant is more than 9 which is evaluated as good and suitable.

By absorbing heavy metals in the soil and accumulating elements in the plant organ, which is a medium accumulator, Acacia plays a crucial role in removing the pollutants from the ecosystems of the region and can be useful in phytoremediation. In this study, the biochemical response of Acacia to heavy metal pollution was investigated and the results showed that although the concentration of chlorophyll in infected Acacia decreased compared to the control condition, the amount of ascorbic acid and proline in the plant increased which strengthens the plant's resistance against pollution; in fact, it can be said that Acacia trees have the ability to react optimally against heavy metal pollution. Nevertheless, in Bandar Abbas, unfortunately, the invasive species of American Acacia has been planted among native Acacia, and due to the deep roots of this invasive species, the health of the native species has been endangered. On the whole, the results of this research showed that Acacia, which is a native species, has the ability to absorb heavy metals and remove them from the environment. Therefore, it is suggested that by spreading Iranian Acacia and removing the invasive American species, we can revive the ecosystem of the industrial area, prevent environmental pollution and take positive steps towards environmental protection.

  Wind erosion is affected by climate change and several droughts have caused environmental degradation in arid regions. This process causes sand and dust storm (SDS) phenomenon which is one of the most important challenges in fragile areas. This phenomenon is harmful for human health and causes socio-economic problems. Over the past two decades, SDS have been increasing in Iran, particularly in the south-east of the country. Therefore, in order to manage this environmental phenomenon in arid areas, it is an urgent need to identify the dust storm sources. The changes of factors such as vegetation, soil moisture, slope, land temperature, and geological units have effective roles in the occurrence of dust storms. So, investigating the changes in these factors is an effective solution to identify dust storm sources. In this regard, using remote sensing data is one of the effective methods for the detection and mapping of dust storms resource, which combined with field methods, provides a coherent approach to manage and control this phenomenon. This study aimed to identify dust sources and storms in the southeast of Iran with emphasis on the Sistan dust storm by using field work and remote sensing data.

The study area is located in the south east of Iran and contains some of the border areas of Iran and Afghanistan (including some parts of the south Khorasan and Sistan and Baluchestan province in Iran as well as Farah and Nimroz province in Afghanistan with coordinates of 60˚ 16′ - 61˚ 36′ east longitude and 29˚ 8′ - 32˚ 32′ north latitude). In north of the study area, the mountainous and low-altitude areas are intertwined but the southern area is mostly flat and lacks topography and natural features. The most important characteristics of this area is 120-day winds, which sometimes reach speeds of more than 120 kilometers per hour and is accompanied by high intensity of sand and dust storms. In this study, to identify dust storm sources, the combination of remote sensing, field study and wind analysis methods are used. To achieve this purpose, at first effective factors in the occurrence of dust storms such as vegetation, soil moisture, slope, land temperature, and geological units were prepared. In this regard, by using Modis satellite images, map of vegetation, soil moisture and land temperature were prepared by applying Soil Adjusted Vegetation Index (SAVI), integrating temperature vegetation dryness index (TVDI) and Land surface temperature (LST), respectively. Also slope map (using Aster satellite) and geological units were prepared. In the next stage, the fuzzy logic method was employed to combine layers and prepare the map of dust storms source, which is assessed by an error matrix and available dust source map. Detection of sand dust storms were performed by using BTD dust detection indicator. For winds analysis, we used WRplot view 8 Software. In the field study, several dust storms sources were determined and their characteristics were recorded.

    The results showed that the ranges of SAVI index are + 0.6 to -1 and the highest amount of this index coordinate with highest soil moisture (TVDI) and the lowest land surface temperature (LST) area. This area is mostly related to rangeland, combination of wetland-rangeland, hand-planted forests and agricultural lands. The amount of SAVI index and soil moisture reaches its minimum value in the salt marsh lands, abandoned agricultural lands, desert areas and degraded rangeland. By merging the layers and preparing the map of dust storm sources, it was found that the critical dust storms resources coordinate with high land surface temperature and low vegetation and soil moisture areas. In addition, the highest dust source area is in the slopes of 0 to 4 % with geological units such as playa deposits, eolian deposits, alluvium sediment and wet playa deposit. According to the results, the incoming dust storms into the study area come from the east and southeast of south Khorasan province in Iran and the southwest of Farah province in Afghanistan.

  In this study by using effective factors including vegetation, soil moisture, land surface temperature, slope and geological units, the sources of dust production were identified. According to the results, poor vegetation and low soil moisture in flat areas with sensitive formations are the key factors to create dust storm resources in the study area. Also, the most important active hot-spot areas for dust storm is concentrated in the southwest of Afghanistan and north of sistan region (dry lake bed of Hamoon). Therefore, it can be concluded that using satellite images and the studied factors, the dust sources can be properly identified. Furthermore, by using Time series images of modis and the updated dust source maps, a coherent approach can be provided in order to manage and control this phenomenon.

Urmia Lake, which has been located in the northwest of Iran, is the largest saltwater in the Middle East. Unfortunately, nowadays various factors have exposed it to dryness and wind erosion, the result of which is the increase in soil salinity, the thinning of solute crystals, and the occurrence of dust storms. If this lake becomes dry, the climate of the area will change to hot climate and salt storms will start. Therefore, we must find new ways to control and prevent the occurrence of wind erosion. Identifying the nature of these dusts, especially their morphology, is important in providing solutions to deal with the crisis. Investigating the characteristics and morphology of dusts in the region is also useful in predicting ways and controlling factors to reduce their damages, and dust morphology is a practical method to determine their origin. Investigation of the properties and characteristics of rising dusts from this area can be useful in predicting and controlling ways to contrast/withstand their damages.

For this purpose, three flat sites without vegetation and prone to fine dust production were selected from the eastern shore of Urmia Lake. Each site was divided into 3 layers based on the height from sea level, but the first layer was omitted from the studying areas because of the high soil moisture due to low distance to lake, which results in decreasing dust production by this layer, and eventually 2 random samples (0-5 cm) were picked up from each layer. This research study was carried out based on 12 selected soil samples from 3 sites and their layers. The soil samples from 0 to 5 cm depth, as a surface soil of layers, were transferred to trays with dimensions of 3 x 40 x 30 cm in the wind tunnel of agriculture faculty of Tabriz University, with 370cm length, 50cm width and 70cm height. Subsequently, wind erosion was simulated by applying the maximum wind speed of 45 meters per second for 15 minutes at each height. Then, the dust particles released at 2 heights of the wind tunnel (10 and 30 cm from the floor of the device) and the control soil sample were sent to SEM to get their images. After processing these row images, the quantitative amounts of morphological properties were obtained. Finally, the statistical analyses were performed on these properties. Using a nested design to find the effect of factors such as the location, layer and height of the wind tunnel on the morphological characteristics of soils in the windblown dust.

The images which had been adopted from SEM were analyzed in Image J application and 5 parameters (perimeter, circularity, roundness, accept ratio and solidity) were calculated for each particle in samples and the average of these parameters for each soil sample was listed. The presented data were analyzed in Minitab application by using the fully nested method and for conducting these analyses, the test of normality of data was performed on data list. The results for each parameter were presented in a table which showed the effect of site, layer and location height of the sediments in wind tunnel.

The obtained results in this research (Table 3) revealed the significant effect of site (5%) on circularity and solidity properties. Also, the effect of height in wind tunnel from floor was significant in 5% just on roundness, and the effect of other factors on morphological properties were not significant. In other words, the size of particles, the area and their parameter in soil samples did not have significant differences and even the wind erosion with given speed in explained time duration didn’t act optional on the size of particles. There were no significant differences between size of diameter, area and parameters of particles before and after the wind erosion. The reason of these results can be dependent on the preparing method of samples for SEM study, in which the samples were rubbed on pin of device and the great grains were separated. Also, the effect of site and height of wind tunnel on roundness and circularity were significant, respectively. As for other morphological properties, the effects of site, layer and the wind tunnel height were not significant and there were no significant differences between the samples.

Soil surface sealing is mostly influenced by the specific prevailing conditions during its formation, and the variables affecting soil surface sealing are the physical characteristics of the soil, the chemical conditions of the soil-water system, the characteristics of rain, and the initial and boundary conditions of the flow (Mualem et al, 1990). It is a common phenomenon in most soils of Iran due to arid and semi-arid climate, weak vegetation and loose soil aggregates. In Kowar plain, as an important Agricultural pole of Fars province, it is very important to determine the factors affecting the formation of surface sealing, to identify the most important characteristics of the soil in controlling the surface sealing formation, and to provide a suitable index to determine the sensitivity of the soil to this formation based on the characteristics of soil erosion, which are very important issues and have been addressed in this research study.

To carry out this research, 80 samples (0-20 cm) were selected from Kowar plain with a variety of physical and chemical characteristics, and after sampling, the samples were air dried and passed through a 2 mm sieve. Then, the parameters of particle size distribution, humidity, organic matter, electrical conductivity and pH of saturated soil extract were measured. In addition, the average weight and geometric mean diameter of soil aggregates, calcium carbonate equivalent, fractal dimensions of one-centimeter soil particles (Bartoli, et al, 1991), percentage of moisture saturation, sodium, calcium and magnesium were determined. The saturated hydraulic conductivity of the samples were measured and the evaluation of soil sensitivity to the surface sealing with seven different indices of SI, RSI, CI, WAS, PR (Permeability Resistance), CSI,   C5-C10 had been performed. Also multivariate statistical methods (cluster analysis, discriminant analysis and canonical correlation) were used for conducting the required analyses.

 After conducting the multivariate statistical method investigations, the results of cluster analysis led to the creation of a discriminant function with a chi-score of 12.73 reaching significance at the probability level of 0.001. This function completely showed the power (ability) to create separation between the two cluster analysis result groups. The organic matter was the most important primary variable that separated these two groups from each other and was significant at the probability level of 0.001. Based on the structure matrix, it was determined that CI, SI and CSI indexes with coefficients of 0.85, 0.58 and 0.30, respectively, are among the most important indices in the separation of these two groups. The performed canonical correlation provided a canonical function with a correlation of 0.99 and a chi score of 626.2. The highest canonical correlation belongs to primarily organic matter and then to clay. Two indices of Soil Stability Index (SI) and Crusting index (CI) were the most important indices having the highest correlation level among the indices. The most important variables influencing the evaluation indices of the sealing surface in the two group’s separation were organic matter and clay, which provided a function with high capability and the highest canonical correlation, respectively.

  The highest coefficient of variation is related to the mass of soil particles with a length of one centimeter (Bartoli model) and the highest canonical correlation in the first degree belongs to the organic matter and clay, it also shows the most important variables, with the highest correlation between these two variables with the mentioned indicators (CI,SI). In addition, two indices of SI and CI were the most important indices having the highest correlation among the indices. The results of cluster analysis, the discriminant function analysis and canonical correlation showed that the most important variables affecting the sealing surface evaluation indices in separating two groups and providing a function with high capability and the highest canonical correlation are organic matter and clay, respectively.  Also based on the structure matrix, the crusting index and aggregate stability are the most important indices that separate the two groups. In fact, the main samples differentiating factors in terms of the sealing surface are the above named indices. Organic matter and soil stability indexes have become significant with a very high correlation and showing a better justification of this indicator (SI) with the characteristics of the soil in determining the sensitivity of the soil to the seal structural formation layer.

   The increasing trend of land destruction in many parts of the world is a serious threat to humanity. Desertification, which is one of the manifestations of this destruction, has affected most of the countries. What is certain is that today the phenomenon of land degradation and desertification in the world and especially in Iran is progressing rapidly and every day it is taking over more areas. The intended method in this research includes the laboratory use of 10 micron bentonite clay through a wind tunnel and determining its hardness by preparing a suspension on the surface of the windy sand; also using different percentages of this clay along with the cultivation of seedlings of Nitraria schoberi, which is resistant to salinity and dehydration. This method is of interest and can be a suitable moisture absorber for storing soil moisture and plant establishment, and also a good alternative to oil mulches that are harmful to the environment. Considering the importance of the problem of dust phenomenon as well as the crisis of drought and lack of water in Sajzi region of Isfahan city, the aim of this research is to establish vegetation cover in critical areas where there is no possibility of fighting except oil mulch or it is difficult to do so. More specifically, the experiment is done by using 10-micron bentonite clay in the pit of Nitraria schoberi seedling cultivation and sprinkling it on the surfaces of the harvesting and transportation area, while reducing the frequency of irrigation and reducing the amount of wind erosion.

In this research, which investigates the use of processed bentonite clay in moisture storage to control soil erosion, by adding this material to the soil, its ability to control wind erosion was investigated in the form of statistical analysis. Bentonite clay can be used with less volume and longer shelf life to control desertification. The 10-micron bentonite clay used in this research is homogeneous in water and can be used to control wind erosion on the soil surface; it reduces water consumption, increases seed germination and increases crop yield. Vegetation can be an effective factor in increasing the roughness of the soil surface and reducing the wind speed. The higher the density of vegetation and the longer its duration on the soil surface, the greater its role in preserving and maintaining the soil.

Effect of bentonite treatments on moisture content In the field experiments, a randomized complete block design was implemented, in which 10-micron bentonite with percentages of 2, 4, 6, 8 and control were used in the cultivation pits with the symbol of Nitraria schoberi seedling cultivation. Also, in 7 time stages of irrigation stress after cultivation (6 periods of alternating irrigation with intervals of 18 and 32 days) and the last irrigation period with an interval of 54 days, the soil sampling of the cultivation pits was done with an auger, and after being transferred to the laboratory, the percentage of moisture was determined. In this experiment, the effect of bentonite on the moisture level at the depths of 0-10 and 10-20 was statistically significant at the level of 1%. The results of comparing the averages showed that in the first stage of sampling to determine the percentage of moisture in the depths of 0-10 and 10-20 cm, with the increase of bentonite, the amount of soil moisture increased significantly. The highest percentage of soil moisture was observed in treatment 8 and the lowest in the control treatment. The amount of soil cell resistance According to the results of variance analysis of the data, the effect of bentonite treatments on soil hardness and erosion was significant at the level of 1 and 5%. Speed 5.7 was obtained in the bentonite treatment of 4 grams per liter and the lowest amount was obtained in the control treatment. In speeds 11 and 28, the highest soil cell resistance was observed in the treatment of 4 grams of bentonite and the lowest amount was observed in the control treatment.

Today, the phenomenon of wind erosion and its consequences is considered as one of the processes of land degradation in arid and semi-arid regions. The preliminary economic assessment of the use of 10-micron bentonite clay instead of other moisture absorbents in maintaining moisture and reducing irrigation frequency shows that this material is easier to access and the cost of its preparation is much lower. The positive effect of bentonite in reducing soil erosion can be due to the fact that bentonite is a clay mineral from the montmorionite family with expansion properties that is created by the weathering of volcanic ash. Also, due to its unique properties, it can be used in increasing the pulp index of the source soils. According to the results of this research, bentonite mineral can be effective in controlling the internal erosion of materials, so that the amount of erosion decreases with the increase of bentonite percentage. The results of this research on the reduction of erosion rate by increasing the bentonite percentage of the soil are consistent with the results of the research of Zumardian and Khushkho (2013). The results of this research showed that according to the method applied in random complete blocks, different treatments of bentonite had an effect on the moisture level and also on the hardness and erosion of the soil in the wind tunnel and shear vane stage. The effectiveness of the soil depends on the amount of bentonite used, the amount of moisture and wind speed, so with the increase in the amount of bentonite in the soil, the hardness and moisture of the soil increased as well.

Organic matter is one of the factors affecting soil fertility and quality. The presence of organic matters increases the stability of aggregate, increases water retention in soil, reduces bulk density and thus reduces soil erosion. Biochar is one of these organic matters which is a carbon-containing and porous solid produced by the chemical heating of organic matter in an oxygen-free atmosphere. It has good physicochemical characteristics for long-term storage of carbon and its preservation in the environment. Different types of raw materials such as plant residues (rice bran, soybean forage, and cotton residues), fertilizers and wood waste (sawdust) are used to produce biochar. The presence of this matter in the soil increases fertility, reduces climate change, reduces nutrient leaching from the soil, increases the soil moisture retention and increases the cation exchange capacity, resulting in increased soil quality. Given the importance of biochar and its role in improving soil quality indices, the present study was conducted with the aim of investigating the effect of different levels of biochar prepared from pistachio and walnut hulls and shells on some physical and chemical indicators of soil.

The effect of four types of biochar prepared from hull and shell of pistachio and walnut, at three levels (zero, two and four percent by weight) on two soils with sandy loam and clay loam textures and with three replications were examined in a completely randomized factorial design. To produce biochar, pistachio and walnut hulls and shells were collected from pistachio and walnut orchards in Iran-Kerman Province-Rafsanjan region. These materials were converted to biochar under pyrolysis conditions. The temperature used in this process was 400 C° and the conversion time of raw materials to biochar was four to five hours. Particle size selection was different according to different articles and in this study; therefore, a particle size smaller than 45 meshes was selected. Biochar (at the mentioned levels) was added to five kilograms of soil and poured into pots. The samples remained intact for four months. During the period, the moisture content of the samples was maintained within the field capacity. At the end of the period, the soil was sampled and the physical and chemical characteristics of the soil were examined.

The results showed that with increasing the levels of biochar, no significant effect was observed on the electrical conductivity of soils. In relation to the changes in pH, the effects of the biochar obtained from the hull of walnut and shell of pistachio were significant, so that the application of the first increased and the second decreased the soil pH in a significant manner. On the other hand, after adding biochar, the soil bulk density decreased. Furthermore, the application of the biochar obtained from the hull of pistachio and shell of walnut in clay loam soil and that of shell of pistachio in sandy loam soil had significant positive effects on aggregation. Moreover, the use of the biochar obtained from the hull of walnut increased the soil water holding capacity in sandy loam soil. Finally, in both clay loam and sandy loam soils, the biochar obtained from the hull of walnut resulted in the highest values of S index among the used biochar types.

In general, the results of this study mainly indicate the positive effects of the use of biochar on soil properties, and it seems that the amount of their impact is a function of the type of biochar and soil texture. Also, based on the results of this study, using walnut hull biochar in sandy loam soil increases the water retention capacity of the soil, and this is due to the micro porosity of biochar. This can be a good solution, especially in arid and semi-arid regions. However, it should be noted that increasing biochar level leads to increased soil salinity, so appropriate levels of this material in the soil should be used. Also, the biochar produced from the walnut hull in both clay loam and sandy loam soils yielded the highest values of S index among the biochar types used. Dexter index, as one of the indices of physical quality of soil, has a special effect on root growth capacity of plants. Finally, it is recommended that the combined effect of these biochar types (hull and shell of each biochar together) be investigated in the soil to determine whether their functional groups compete with each other or complement each other.

One of the important issues in the sustainable management of soils in order to optimize the agricultural production and preserve natural resources is the assessment of soil quality.  Soil quality is the capacity of a specific kind of soil to function to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation. It is also considered one of the most important factors investigated in the assessment of soil management. Knowledge of quality changes is necessary for sustainable soil management. Since soil quality cannot be measured directly, it must be obtained from the relevant characteristics. Soil quality characteristics are sets of measurable soil characteristics that are sensitive to land use change, management, or conservation operations. Using soil quality indicators is a useful tool to determine and compare soil quality. The purpose of this research is to quantify the soil quality index using multivariate analysis in different soil types in Urmia Plain.

In this research, according to the semi-detailed soil studies of Urmia plain, 24 soil profiles from different soil units of this area, which are mostly under garden and agricultural use, were excavated, described, sampled, and classified, and 96 samples were also collected from soil solum. 2 profiles in Typic Haploxerepts (TH1) soil type, 4 profiles in Fluvaquentic Endoaquepts (FE) soil type, 6 profiles in Typic Calcixerepts (TC) soil type, 2 profiles in Typic Endoaquepts (TE) soil type, 5 profiles in Fluventic soil type Haploxerepts (FH) and 2 profiles were located in Typic Halaquept (TH2) soil type. At a certain distance from the excavation site of the profiles, four soil samples were taken from four directions of the profile. Using principal component analysis (PCA), among 22 characteristics affecting soil quality (TDS), the minimum characteristics affecting soil quality (MDS) were determined. Then the soil quality in different soil types of region was evaluated using two cumulative soil quality indices (IQI) and Nemuro Quality Index (NQI) and each of them was evaluated in two sets of TDS and MDS in different soil types.

Among the measured parameters, pH had the lowest (2.5%) and salinity (EC) had the highest coefficient of variation (154.6%) in the region. Among the 22 measured soil properties, sodium absorption ratio (SAR) in the first component, nickel element (Ni) in the second component, cation exchange capacity (CEC) in the third component, sand percentage in the fourth component, active lime (ACCE) in the fifth component and absorbable phosphorus (PAW) in the sixth component were selected as MDS. The examination of the soil quality index showed that the soils of this region mainly have quality grade II (57%). The highest average value of selected soil quality index related to MDS mode in IQI model was calculated with a value of 0.79 in Fluventic Haploxerepts soil type and the lowest average value related to TDS mode in NQI model was calculated with 0.28 value in Typic Halaquepts soil type. The correlation coefficient between the soil quality index with the total category and minimum data in both IQI and NQI models was equal (R2=0.48).

The sequence order of both soil quality indices (IQIa, NQI) in both TDS and MDS conditions in the types of the studied area was as FE>TE>TH1>TC>FH>TH2. Therefore, the highest soil quality was observed in the Fluventic Endoaquepts type and the lowest soil quality was observed in the Typic Halaquepts type. Based on the results, both indicators were classified in three classes (good, medium and poor) in TDS and MDS sets. In the case of TDS, 57.83% of land (equivalent to 19731 hectares) had good class (II), 30.48% of land (equivalent to 10400 hectares) had medium class (III) and 11.69% of land (equivalent to 3990 hectares) they had poor class (IV); (very good (I) and very poor (V) class were not observed). In MDS mode, 18.56% of lands (equivalent to 6333 hectares) had very good class (I), 27.15% of lands (equivalent to 9264 hectares) had good class (II) and 54.29% of lands (equivalent to 18524 hectares) They had medium class (III); (weak class (IV) and very weak (V) were not observed). The degrees of IQIa and NQI indices were similar and were divided into three classes (good, medium and poor). As a result, 39.3% of land (equivalent to 13412 hectares) was in good class (II), 24.59% of land (equivalent to 8392 hectares) was in medium class (III) and 1.36% of land (equivalent to 12317 hectares) was placed in poor class (IV); (very good (I) and very poor (V) classes were not observed). In general, the soils of the region were limited in terms of the studied indicators in the parts leading to the lake, and there was a significant correlation between IQITDS and IQIMDS, and between NQITDS and NQIMDS. This shows that the determined MDS set can be a good representative of TDS in soil quality assessment in Urmia Plain.

Carbon dioxide emissions caused by human activities, industrial activities and other sources are increasing day by day. The increase of this gas as an important greenhouse gas can cause fundamental changes in global temperature and climate change. Soil respiration is one of the main natural ways of releasing carbon dioxide into the atmosphere in terrestrial ecosystems, and by studying it, one can gain a lot of knowledge about the global carbon cycle. Tree species can influence soil microbial respiration by affecting biogeochemical processes through the amount of litterfall. On the other hand, the different directions of the trees, due to the changes in the radiation angle, which affects the amount of moisture and temperature, probably cause different responses of soil microbial respiration.

In this research, spatial changes of soil microbial respiration by integrating geographical aspects (north, west, east, south) and five different distances (0.5, 1, 1.5, 2 and 2.5 meters) from the tree trunk for the study of soil microbial respiration in three different oak species (Quercus infectoria Oliv., Quercus brantii Lindl. and Quercus libani Oliv.) were carried out in Baneh, Armardeh forests. Three oak trees were selected in the types with the dominant percentage of the desired species (almost identical in terms of height, diameter at breast and canopy). Soil microbial respiration was recorded using Anderson method and moisture in the laboratory and the temperature of the soil were also recorded at the same time sampling at the sample site (soil samples were taken from a depth of 0-10 cm). One-way analysis of variance and Tukey's test were used to check the significance of the difference in the measured characteristics between different oak species.

   The results showed that there was no significant difference in the parameters of microbial respiration and moisture between the different aspects of each of the different oak species. The results of soil temperature also showed a significant difference in Quercus brantii species between different aspects, and no significant difference was observed in Quercus infectoria and Quercus libani species. On the other hand, there were significant differences between different distances from the trunk. Also, the results of comparing the average soil microbial respiration between different species were not significant, but the results of comparing the average between different oak species at different distances showed differences between the three species. The main environmental factors in this study included soil temperature and soil moisture, which were significantly affected by spatial heterogeneity. The average soil temperature related to Quercus brantii species had a significant difference in different aspects, which could be due to the difference in the intensity of lighting during the day and the aspects of the sunlight and the change of shade over time. There was a difference in soil temperature at different distances in all three species, and this could be due to the low canopy density of the Zagros forests.

 Single trees affect the substrates on which they grow and may leave their traces on the soil through the influence of the canopy and roots. The "single-tree influence" concept envisions the soil landscape as a mosaic of small patches that are spatially and genetically linked to individual trees. There are two aspects to this concept: first, within the circle of influence of each tree, soil properties vary predictably in relation to distance from the trunk and crown edge, and second, at any location relative to the trunk and crown, the degree of feature development varies as well. Soil properties are different among tree species. In other words, the organic matter produced by any tree species is different and the related grass cover contains different proportions of nutrients, lignin and secondary metabolites, which determine the quality of organic matter and the rate of decomposition. This study also showed that the spatial heterogeneity in soil temperature and moisture content may be intrinsic mechanisms that drive differences in soil microbial respiration. These findings can deepen our understanding of changes in microbial respiration and soil respiration and clarify the ecological role of different species for us.

Groundwater is one of the most important water resources that is always used by humans in different sectors. The composition and chemical quality of groundwater sources are always threatened by natural factors such as climate, soil type, geology, topography, precipitation and evaporation, as well as human factors such as population growth, extensive agricultural activities, and industrial development. Hence, hydrogeochemical researches can provide very detailed information about the effect of the aquifer materials of the study area, the route of recharge and discharge, the areas of evaporation from the groundwater, the effect of surface water on the groundwater of the region, as well as its quality in various uses for decision makers. This research  was conducted to 1) compare and determine the significant difference (using the paired samples t-test) between physicochemical parameters in the statistical period under review (between wells and springs), 2) use geochemical ion ratios in order to discover the origin of ions and influencing processes that are responsible to alter the concentration of ions in the studied water resources, 3) investigate and identify the ion exchange process (normal and reverse) using chloro-alkaline indices and some hydrogeochemical graphs, and 4) identify saline water intrusion from subsurface layers or human pollution into the groundwater sources.

 In this study, 14 piezometric wells in the eastern part of Gorgan plain and 8 springs located in the heights between the cities of Ramyan, Minoodasht, Kalaleh and Gonbad were selected for hydrogeochemical study for which hydrogeochemical processes and qualitative changes of physicochemical parameters results (including Ca, Mg, Na, K, HCO3, Cl, SO4, TDS, pH and EC) were used over a period of 10 years. To compare and determine significant differences between physicochemical parameters in the statistical period under study between wells and springs, paired samples t-test and analysis of variance were performed in Minitab software. Before performing the paired sample t-test, normality of the data was checked using the Anderson-Darling test. In  paired samples t-test, if the p-value estimated by the software is greater than or equal to 0.05, with a probability of 95%, the hypothesis H0, which means that there is no significant difference between the average of the investigated treatments, is accepted and the hypothesis H1 is rejected. However, if the calculated p-value is less than 0.05, the hypothesis H0 is rejected with a probability of 95% and the hypothesis H1, which means that there is a significant difference between the averages of the investigated treatments, is accepted. Next, the maps related to the spatial changes of the groundwater parameters were plotted in the GIS environment and by using the IDW method, and then the trend of their changes in the studied area was interpreted. Aq.QA software was also used to better analyze the hydrogeochemical data and to draw the stiff and piper diagrams. Finally, to identify the factors governing changes in groundwater quality and also to investigate the relationships between variables, Gibbs diagram, ion ratios, and compositional diagrams have been used. All the mentioned graphs were prepared using Excel software.

   The spatial distribution of hydrochemical parameters showed that the concentration of most physicochemical parameters due to groundwater flow (from west to northwest) is increasing. The results of the investigation of the water type in the springs showed that magnesium bicarbonate (Mg-HCO3) is the dominant type of water in the studied springs. Unlike springs, a wide range of water type is observed in piezometric wells (Mg-HCO3, Mg-Cl, Na-Cl and Na-HCO3). Also, Ca-Mg-CO3-HCO3 bicarbonate facies and then mixed Ca-Mg-Cl-SO4 facies are the most abundant in water resources. Based on the distribution of water source samples in the Gibbs diagram, the chemical composition of all the samples, except for one sample related to the well, is controlled by the reservoir rock of springs or piezometric wells in the plain. Since the main ions show a linear relationship with TDI, it can be concluded that there is a possibility of intrusion of saline water containing sodium and chlorine ions or dissolution of halite minerals in the groundwater of the plain. The results of ion ratios showed that groundwater is recharged by dolomite, dolomite-limestone, and lime-dolomite formations associated to different geological periods is the main factor controlling hydrogeochemical parameters in the springs. But in the observation wells of the plain, in addition to the above cases, the weathering of silicates and the small intrusion of saline water into the ground water table have caused changes in hydrogeochemical parameters. The results of ion exchanges showed that the normal ion exchange process has a more effective role than the reverse ion exchange process in final concentration of main elements in the groundwater of studied water sources.

The changes in the concentration of ions in the springs are much less than the observed wells in the plain. Bicarbonate is the dominant anion in both well and spring water sources. Nevertheless, in the two wells no. 3 and 10 chloride ions prevail, which can be caused by the intrusion of saline water from the lower layers into the groundwater. Based on the spatial distribution of the physicochemical parameters, the concentration of most of the parameters in the direction of the groundwater flow is increasing due to the presence of layers with poor quality, the infiltration of urban sewage and agricultural effluents, as well as the intrusion of saline water from the subsurface layers. The investigation of the water type of the springs shows that magnesium bicarbonate is the predominant water type. Therefore, it can be concluded that the reservoir rock that recharges the springs is more than dolomite limestone. Similar to the springs, all the wells drilled on the edge of the highlands have the dominant type of magnesium bicarbonate. But by moving away from the mountain front and changing the concentration of some ions due to environmental and human factors, the type of groundwater becomes more diverse. Based on the composition graphs, it can be concluded that there is a possibility of intrusion of saline water containing sodium, magnesium, sulfate and chloride ions or the dissolution of some minerals such as halite and gypsum sulfate, especially in the groundwater of the plain. The results the ionic ratios related to the intrusion of salt water in water resources show the good quality of the groundwater and the recharge of the aquifer by limestone formations. Considering that the springs are located in the groundwater recharge area (fresh water), they are less affected by human pollution and, as a result, they have better chemical quality. On the other hand, the wells situated in the plain, due to human activities such as the excessive use of nitrogen fertilizers for agricultural products and the infiltration of urban or domestic sewage into the aquifer along with the intrusion of saline water into the groundwater in some areas of the plain show a greater tendency to become salty.

Soil erosion is one of the main factors of land degradation and desertification in large areas of the earth's surface, which is the result of the interaction of human and natural factors causing the destruction of natural ecosystems such as rangeland, forests, and agricultural ecosystems. Factors such as topographical settings, land use and land cover change, intensity of rainfall, soil properties, and wind can also be accelerated by human activities of intensive agriculture, deforestation, and tillage on steep slopes. Many models have been suggested for estimating water erosion such as USLE, RUSLE, WEEP, and EPM.  According to previous studies, the global model of soil erosion has been used in the zoning of areas with high erosion risk, but very few studies have used the USPED model, which unlike the RUSLE model that only identifies the erosion areas, this model identifies also the amount of sediment. In a study conducted by Zakerinejad and Maerker, 2015, they assessed and zoned water erosion in the Mezayjan watershed in Fars province by combining the USPED model and the Strean Power Index (SPI). The results indicated the high capability of the proposed model. It is also used to identify high erosion risk areas. The Khasuye watershed is one of the sub-watersheds located in the south of the country and in the territory of Fars province, which is affected by the severe types of water erosion leading to the loss of surface fertile soil, filling of reservoirs of dams and the reduction of water quality. Therefore, planners can consider the preparation of the potential map of the rate of erosion and sedimentation in the identification of susceptible areas in order to prioritize the implementation of soil protection and watershed management operations.

The parameters of the USPED model were estimated using different data sources by ArcGIS 10.8. The rainfall erosivity factor (R value) was estimated from the annual rainfall data of six meteorological stations located throughout the study area. The soil erodibility factor (K value) was derived from the soil samples collected from our study area. The topographic factor was calculated by analyzing a digital elevation model (DEM) with a spatial resolution of 12 m from TanDEM-X. The crop factor (C) weas derived from Sentinel-2 satellite images and conservation practice factor (P) was considered 1 because of no special soil practice in the study area. Since the spatial resolution of the applied factor maps is different, it requires resampling of the factor maps. So, in this study, the nearest neighbor re-sample sub-tool of the data management toolbox in the ArcGIS platform was used.

The study used the GIS–USPED interface model for analyzing the spatial distribution of water erosion in Khasoue watershed in Fars province. Also, according to the classification result tables of the erosion and sedimentation model of the Khosoye watershed, about 39% of the studied area is in the low and insignificant erosion class, which is mostly in the central and low slope areas of the basin, and about 24% corresponds to the low and very low sedimentation class.  It is possible that these areas are better next to areas with low erosion and low areas with a higher slope of the basin (Table 2). It should be noted that this interval is due to the change of vegetation and physiographic factors and human activities. The lowest rate of erosion is in the center of the basin, and the highest rate of erosion is in the western and northern steep areas of the studied basin. The final results obtained from the application of the USPED erosion-sedimentation model in the studied basin showed that the amount of erosion and sedimentation varies from 0.1 to more than 30 tons per hectare per year, that signify erosion areas with a negative number and sedimentation areas with a positive number (without sign) area.

Among the several fundamental approaches for calculating soil erosion rate, the USPED model is a critical tool for conducting improved conservation planning. The implementation of this erosion model can help to identify the places that are affected by erosion, especially the inaccessible areas, and by identifying these places, the necessary management can be applied to control and reduce soil erosion in these areas.