h. r. karimzadeh

Environmental pollution is one of the consequences of unsustainable development, which has been intensified by population growth, urban expansion, industrialization, and the consumption of fossil fuels. This research aims to monitor potentially toxic elements (PTEs) in some areas of Isfahan province using a dendrochemistry approach, which analyzes the annual core rings of Tehran pine tree (Pinus elderica). Trees with a minimum age of about 50 years were selected in three regions including Isfahan, Zarinshahr and Ardestan, and then sampling was conducted on three trees in each station using an increment borer. The samples were separated with a time interval of 10 years and analyzed to measure the elements with potential toxicity. The thickness of the growth core rings of plants in recent decades has decreased by 33, 26 and 22% in Ardestan, Zarinshahr and Isfahan, respectively, compared to earlier decades. In most samples, the enrichment factor calculated from tree rings in the two locations of Isfahan and Zarinshahr was greater than one and an increasing trend over time was observed for Fe, Zn and Cr elements. The higher concentration of Fe and Pb in tree rings of Zarinshahr and Isfahan, especially in the most recent decade, could be related to the existence and expantion  of industrial activities such as metal smelting and casting.

Recognition of the influential environmental factors in natural ecosystems plays a significant role in the success of the life cycle of existing plant species. This study was conducted to investigate some of the dominant ecological features affecting the morphological alterationsof the reproductive organs of Gundelia tournefortii L. in 11 major habitats of this species in the central Zagros region, Iran. Two influential features of vegetation (canopy cover percentage and density per unit area), 14 environmental factors in three groups of physiography, soil and climate along with nine morphological features related to reproductive organs of G. tournefortii L. (inflorescence and seed) were assessed in its major habitats, following the relevant assessment methods. Results were analyzed using Pearson's correlation test, Principal Component Analysis (PCA) and cluster analysis. The environmental factors, including absorbable potassium, soil shear strength, electrical conductivity, length of dry period, average annual temperature, average number of frost days and average altitude were the most important dominant ecological features in the morphological variations of plant reproductive organs.  Identifying the relationship between vegetation and the affecting ecological features plays  a very efficient role in achieving accurate information sources in the management of natural habitats.

In order to make decisions for regional planning and achieve sustainable development, it is necessary to quantify land use and land cover changes. In this study, the land use and land cover maps of the Zayandehrood Dam watershed were prepared for the period of 1991 to 2021, using Landsat satellite images, and the changes that occurred in this period were revealed. Using the land change modeler (LCM), land use and land cover and their future changes for 2051 were modeled and predicted. The results showed that in the period between 1991 and  2021, the coverage of poor rangelands with 51,871 hectares of change had the largest decreasing trend, and the agricultural class had the largest increasing trend with 71,478 hectares of change. The largest decline in the period from 2021 to 2051 is related in the coverage of the fair rangelands class with 66192 hectares, and the agricultural class potentially has the largest increasing trend with 70328 hectares of change. The findings of this research will be useful for policymakers and planners. They can use the findings of this study for spatial planning in the region, managing the process of land use and land cover changes for sustainable development.

Habitat degradation is one the important reasons of plant species extinction. Modeling techniques are widely used for identifying the potential habitats of different plant species. Thus, the purpose of current study was to determine potential habitats of Zalzalak in Lorestan Province. Species presence data and 23 environmental variables were collected in Lorestan Province. Correlation analysis was then applied to reduce the environmental variables into nine effective ones and potential habitat of the species was determined using five models including Maximum Entropy (MAXENT),Generalized Linear Models (GLM), Generalized Additive Models (GAM), Multivariate Adaptive Regression Splines (MARS) and Generalized Boosting Model (GBM). Models were evaluated with receiver operating characteristic (ROC) plots, true skill statistic (TSS) and Kappa coefficients. Results showed that ROC and Kappa coefficients were excellent for all models and TSS values were excellent for GBM and MAXENT, good for MARS and GAM and medium for GLM model. According to the combined model, 40% of the province was classified as suitable and 60% as unsuitable. The precipitation of the three coldest months of the year, annual rainfall and elevation were the most effective environmental variables in Zalzalak habitat mapping. The maximum presence of the species occurred at the rainfall and elevation range of 160–220 mm and 1300–1850 m, respectively. Due to the high accuracy of the Zalzalak suitable habitat map, it can be used by related organizations, as an appropriate tool for reclamation of degraded regions and conservation of current habitats.

Stabilizng sand dunes has been one of the main challenges in the arid regions. So far, different kinds of mulches have been used extensively for sand dune stabilization. This study was carried out to determine the optimum composition, concentration and thickness of clay mulch for sand dune stabilization. For this purpose two soil samples from clay flats of a playa with different amount of salinity from Ardestan area were used to make clay mulches. A sand dune sample was selected as bed for applying the mulch. To select the right ingredient and treatments, clay samples were mixed with sand and different amount of water, and sprayed on sand dune bed. In addition, wheat straw was added to some mixture to test its effect on stability of the mulch. Treatments with lowest crack and highest penetration of mulch in sand bed were selected for the experiment in this study. Mulch treatments contained (1): 250g sand dune + 250g clay + 25g straw (2) 250g clay + 25g straw (3) 250g sand + 250g clay (4) 250g clay (5) 125g sand + 125g clay and (6) 125g clay. All treatments were mixed with 500ml water. The experimental design was a CRD with a 6(mulch) * 2(thickness)* 2 EC factorial method with 3 replications. The results showed that clay mulch were resistant to wind erosion, but erosion took place when they had been bombarded with sandblast. The mulches with straw showed the highest resistance to erosion as compared to other treatments. With increasing the number of mulch layers, resistant to erosion also increased. The added stability of mulch was due to the increase in mulch thickness and also increases in clay and silt content. The overall result of this study shows that the mulch with two layers and higher mixture of clay and sands was the best treatment for the stabilization of sand dunes.

Clay minerals deserve special attention as they play a crucial role in many soils. The clay mineralogy of five gypsiferous soils from different landforms in eastern Isfahan was investigated using X-ray diffraction (XRD). In addition, soil aggregates and wind-deposited sediments were examined by scanning electron microscope (SEM) and analyzed by energy dispersive X-ray analyzer (EDX). The results indicate the presence of palygorskite, mica, kaolinite, chlorite, and quartz with a trace amount of vermiculite and randomly interstratified layers in all soils. Smectite occurs in soils of both the piedmont plain and old river terrace, but not in the alluvial fan soils. Mica, chlorite, quartz, and kaolinite were probably inherited from the parent material. Palygorskite seems to increase with depth in the alluvial fan, whereas, in the old terrace soils, this clay mineral decreases with depth. Palygorskite present in alluvial fan soil appears to have been formed authigenically when the basin was covered with shallow hyper-saline lagoons toward the end of the Tertiary. Palygorskite in the old terrace seems to be mostly detrital and an eolian origin of palygorskite is likely because a large amount of palygorskite is present in upper soil horizons. A higher proportion of smectite in deep soils of the old terrace, as compared with palygorskite, suggests the possibility of authigenic formation of smectite from palygorskite. .

For the study of field wind erosion and the design and evaluation of wind erosion control techniques, detailed observations of soil particle transport and vertical destribution of eroded soil particles are needed. The objectives of this study were: 1) To describe one device for soil transport particle measurement, i. e. the BSNE sediment catcher and 2) To assess vertical distribution of wind–eroded sediment with height in eastern Isfahan. The BSNE sediment catcher is a wind erosion sampler that traps eroded material at seven heights of 0.24, 0.60, 1.08, 2.00, 3.00, and 4.00 m above the soil surface. Each trap consists of a steel container with an inlet and outlet, mounted on a wind vane that rotates about a central pole. Before using the sampler in the field, it was tested and calibrated in the wind tunnel. The results showed that the average trapping efficiency with speeds ranging from 5.2 to 7.2 m sec-1 for 4 different wind–eroded sediments was 0.44 to 0.68. However the trapping efficiency depended on wind speed, particle size distribution, particle density and type of sediment. The sampler had the lowest efficiency for particles < 44 μm. A BSNE sediment catcher was installed in Babaii Air Base. After a sampling period, the sediment in each trap was collected and weighed. The trapped materials were a mixture of saltation and suspension particles. Vertical distribution of wind–eroded sediment showed that the amount of soil collected decreased with increased height and the percentage of fine particles (<63μm) increased with height. The amount of trapped materials for each cm2 frontal intake with increased height were 12.00, 3.42, 1.44, 1.56, 0.75, 0.21, and 0.39 g cm-2, respectively, for the one sampling period.

Due to physiography and weak structure, the pasture soils in Boroojen are potentially degradable. Converting pastures to agricultural land accelerates the degradation processes. A study was conducted in 1999 to show the effects of almost 20 years of farming on originally pasture land on soil physical properties, fertility, and tilth index of pastures in Boroojen region in Chahar Mahal and Bakhtiari Province (central Zagrous). Soil texture, clay content, bulk density, organic matter, saturation moisture percent, cone index, plasticity index, mean weight diameter and aggregate size and distribution, nitrogen, phosphorus, and potassium were measured. After 20 years of cultivation, bulk density increased about 20% while organic matter decreased by 30%. Cone index was lower in the undisturbed pasture but nitrogen and phosphorus contents were higher compared to the disturbed pasture. The undisturbed pasture contained more larger (> 1 mm) aggregates, while the disturbed pasture had more smaller aggregates. Sustainable use of natural resources will lead to their long term workability, while negligence of conservational practices including appropriate farming management practices will result in the destruction of these resources.