جستجوی مقالات مرتبط با کلیدواژه « ایران مرکزی » در نشریات گروه « آب و خاک »

Mineralogical composition, soil morphological properties, and magnetic susceptibility were affected along soil evolution in soils. That is why micromorphology helps in performing soil classification and evolution studies, as well as making soil management practices much more efficient. Clay mineralogy is a useful tool that helps in better understanding soil forming factors and processes. Soil magnetic properties are complex reflections of chemical, geological, and biological soil characteristics. Thus, knowledge about factors affecting magnetic susceptibility can help in better understanding and interpreting the results obtained in an area. Assessment of soil magnetic behavior might be used in pedology, soil mapping, investigation of soil process variations, parent material composition, sedimentary processes, soil drainage conditions, soil pollution, and separation and identification of soil unit boundaries. The present study was performed to investigate the effects of magnetic susceptibility, clay mineralogy, and micromorphology on soil characteristics, genesis, and evolution.

Seven representative pedons were selected in sedimentary and igneous sections in uncultivated land use and physiographic units: hill, piedmont plain, alluvial plain, and lowland. Physicochemical properties measurements were performed on the collected samples from representative pedons using standard methods. The pedogenic (Fed) and amorphous (Feo) iron concentrations of the extracts were determined using a Vario Atomic Absorption Spectroscope (AAS) instrument. Undisturbed soil samples were selected for micromorphology studies and thin section preparation. Additionally, three soil samples were used for X-ray diffraction (XRD) analyses after carbonates, organic matter, and Fe were removed using Jackson (1965) and Kittrik and Hope (1963) procedures. Finally, the mass-specific magnetic susceptibility of soil samples was determined using a Bartington MS2 meter equipped with the MS2B Dual Frequency sensor, capable of taking measurements at both low (χlf at 0.46 kHz) and high (χhf at 4.6 kHz) frequencies.

Salinization, leaching, and illuviation processes of gypsum and carbonates were observed in the studied pedons. The soils were classified as Aridisols (Soil Taxonomy system) and Solonchacks, Solonetz, Gypsisols, and Calcisols RSGs (WRB system) due to the presence of calcic, gypsic, salic, argillic, and natric diagnostic horizons. The presence of gypsum, carbonates, salt, clay accumulation, and argillic horizon reduces χlf values. The calcite coating located on the clay coating could probably be attributed to the presence of a climate with more available humidity in the past. The range of soil magnetic susceptibility was from 4.3×10-8 to 1264×10-8 m3kg-1. Gypsum infillings, different forms of gypsum, clay accumulation and coatings, and weathered calcite crystals were among the dominant micromorphological features observed in the studied pedons. Montmorillonite, chlorite, illite, kaolinite, quartz, and vermiculite minerals were observed in the studied pedons. Chlorite and illite minerals were dominant in the clay fraction of the studied soils, whereas a portion of these minerals was probably converted to vermiculite. Discontinuities observed in pedon 2 could be accounted for as proof of more available humidity in the past compared to the present time periods. Moisture has caused the removal of potassium and transformation of illite and chlorite to vermiculite. The dominance of illite and chlorite can be proof of initial weathering and evolution in the other studied pedons.

The χlf variations was related to depth trend and physicochemical properties. The χlf values showed a noticeable negative correlation with argillic horizon, gypsum content, carbonate calcium, and salinity. It seems that most of the clay minerals originated from the parent material in the present study, and pedogenic source has rarely taken place. Besides, the χlf and Fe contents were directly correlated. In general, the results indicated young soils with primary development stages in the area under study. Pedon 2 with buried polygenetic soils is an exception.

The present research performed to investigate soil evolution in soils developed on sedimentary and igneous parent materials, northern Kerman. Four representative pedons were selected. Physicochemical properties and Micromorphological features investigated in soil samples. The principal oxides content measured using ICP-OES. Color, clay accumulation, Fe content, and geochemical indices were used to assess soil development in the studied pedons. Studied profiles classified in Aridisols order and Calcite, Gypsic and Argillic horizons were dominant. Mean of pedogenic, free, crystalline, and active Fe contents were determined as 9.4, 0.5, 8.8 g/kg and 0.06, respectively. The values of clay and Fe accumulation indices were obtained 17 (in pedon 3) to 76.5 (in pedon 2) and 24344 (in pedon 2) to 2788 (in pedon 3), respectively. The results showed the correlation between Fe contents and color indices at the 99% level. The mean weight of principal oxides noticeably increased in pedons 1 and 3 compared to other studied pedons. All of geochemical indices, except WIP, showed higher weathering in pedons 1 and 3.The results of color, Fe oxides and clay accumulation and CIW, CIA, PWI, V, PIA, STI and R geochemistry indices demonstrated higher evolution of pedon 3 compared to other studied soils. No significant difference in development rate reated to parent materials change was found. Likely, various evolution of studied pedons was due to intractions among geochemical indices and soil-forming factors and processes.

The main purpose of this research was to study the effect of soil physicochemical properties on aggregate stability and magnetic susceptibility in two aeolian geomorphic units (desert pavement and aeolian clay flat) of Davarn plain in Rafsanjan. After taking 50 samples from the surface soil (0 to 10 cm) of desert pavement and 43 samples of aeolian clay flat, the magnetic susceptibility, mean weight diameter of aggregates and some of their most important physical and chemical characteristics were determined. Results showed that the mean magnetic susceptibility in desert pavement was 842.53 and in clay flat was 632.13 (*10-8 m3 kg-1) which is very high compared to those in soils of Iran and its main reason could be attributed to the parent material of the area. The low mean frequency-dependent magnetic susceptibility in the both study units also confirms this issue. The mean weight diameter of aggregates in the desert pavement varied from 1.20 to 1.93 mm and in the clay flats from 0.54 to 1.80 mm. The findings of this research showed a direct correlation between iron forms (Fed and Feo) with aggregate stability in the both of studied geoforms; however, the level of this correlation was high and significant for Fed. The results also indicated that there is a negative correlation between magnetic susceptibility with electrical conductivity (EC), organic matter (OM) and calcium carbonate equivalent (CCE) in the both of studied units. A positive and significant correlation was seen between total silt, total sand and its fractions with magnetic susceptibility in both geomorphic units. In addition, a negative correlation was seen between the mean weight diameter of aggregates and magnetic susceptibility, which its possible reason can be the presence of a large amounts of sand resulted from aeolian losses and its adverse effects on aggregate stability. The results of regression model indicated that dithionate iron and sand had a significant effect on the magnetic susceptibility; and sand, clay and electrical conductivity had a significant effect on aggregate stability.

Soil magnetic properties reflect the complex chemical, geological and biological interactions occur in the soil. Thus, knowledge about the factors affecting soil magnetic properties helps better understanding and interpreting the results.. The lithogenic magnetic minerals are often found in the coarse soil fractions (sand and silt) and they have inherited from parent rocks. Weathering and soil formation factors may lead increasing or decreasing of magnetic susceptibility. Climate and vegetation type are among the other factors affecting magnetic susceptibility too. Amount and distribution of magnetic susceptibility may also be affected by land use. The main objective of this research was to study the effect of different land uses and vegetation types on the magnetic susceptibility of topsoil related to soil properties.
The study area was located in MahoonakeZiba around the Bardsir region, Kerman Province. The moisture and temperature regimes of the study area were sub aridic and mesic, respectively. The study area is located in the alluvial plain with igneous parent material originated from andesite, volcanic tuff, anddacite. Four land uses including farmland, well-covered pasture, disturbed pasture and degraded dryland farm with similar climate, topography, and parent material were selected. Overall, 60 complex surface samples were collected from the depth of 0-15 cm. The physicochemical analyses were done on the samples after that the soils were air dried, crushed, and passed through a 2 mm sieve. The soils magnetic susceptibility (ᵡ) in low (0.46 kHz) and high (4.6 kHz) frequencies were measured using the Bartington MS2 dual frequency sensor in two replications. The frequency depended magnetic susceptibility (ᵡfd %) was calculated as a development index of soil forming factors reflecting ferrimagnetic particle sizes.
The pH of studied soils were in the range of neutral to alkaline and had the lowest coefficient of variance between measured parameters. The average of soil EC was 1.76 dS/m with a high coefficient of variance. The lowest amount of organic matter was in land use ofdegraded drylandfarm (0.26 %) and the highest was in farmland (2.15 %). The lowest amount of calcium carbonate with the coefficient of variance 12.37 % measured in the degraded pasture and its maximum was in the farmland. The loamy sand and sandy loam textural classes were found in the area under study. The minimum and maximum amounts ofᵡlf were determined in farmland (134.8× 10-8 m3 kg-1)and well-coveredpasture (1778.9 ×10-8 m3 kg-1 ), respectively and the relatively high mean value was 695.83 × 10-8 m3 kg-1. The topsoil of the study area was formed on alluvial deposits with a parent material originated from igneous andesite, tuff and dacite rocks. The high values of magnetic susceptibility of all soils under study could be attributed to the existence of initial magnetic minerals inherited from the parent material. The statistical analysis revealed a significant difference among ᵡlf values (p

Wind erosion is the most important geomorphic process and the main cause of the landscape change in arid and semi-arid areas. This paper focuses on the Dust Storm Index (DSI) with the aim of monitoring wind erosion in Central Iran using meteorology data. The trend of standardized DSI and its three factors which are sever dust storm, moderate dust storm and local dust events were studied using Man-Kendal non-parametric test. It was found that wind erosion is accelerating in recent years. Compared to primary 20 years (1965-1985) DSI rate has been three times more than 30 years ago (1985-2014). The central and southern parts of Central Iran show the highest severity of wind erosion and the severity of DSI decreases by approaching the north. Therefore, considering the sensitivity of these areas, in addition to taking into account prevention programs, they should also be considered in regeneration and control programs.

Soil genesis and development in arid and semi-arid areas are strongly affected by geological formations and geomorphic surfaces. Various morphological, physical, and geochemical soil properties at different geomorphic positions are usually attributed to different soil forming factors including parent material and climate. Due to variations in climate, geological formations (Quaternary, Neogene and Cretaceous) and geomorphology, the aim of the present research was the study of genesis, development, clay mineralogy, and micromorphology of soils affected by climate, geology and geomorphology in Bardsir area, Kerman Province.
The study area, 25000 ha, starts from Bardsir and extends to Khanesorkh elevations close to Sirjan city. The climate of the area is warm and semi-arid with mean annual temperature and precipitation of 14.9 °C and 199 mm, respectively. Soil moisture and temperature regimes of the area are aridic and mesic due to 1:2500000 map, provided by Soil and Water Research Institute. Moving to west and southwest, soil moisture regime of the area changes to xeric with increasing elevation. Using topography and geology maps (1:100000) together with Google Earth images, geomorphic surfaces and geologic formations of the area were investigated. Mantled pediment (pedons 1, 3, 7, and 8), rock pediment (pedon 2), semi-stable alluvial plain (pedon 6), unstable alluvial plain (pedon 5), piedmont plain (pedons 9 and 11), intermediate surface of alluvial plain and pediment (pedon 4), and old river terrace (pedon 10) are among geomorphic surfaces investigated in the area. Mantled pediment is composed of young Quaternary sediments and Cretaceous marls. Rock pediments are mainly formed by Cretaceous marls. Quaternary formations are dominant in alluvial plains. Alluvial terraces and intermediate surface of alluvial plain and pediment are dominated by Neogene conglomerates. Siltstone, sandstone, and Neogene marls together with Neogene conglomerates are among dominant geological formations of piedmont plain. Eleven pedons affected by young Quaternary sediments, Neogene and Cretaceous marls in aridic, aridic border to xeric, and xeric moisture regimes on above-mentioned geomorphic surfaces were described and sampled using Natural Resources Conservation Service (2012) guideline. Physicochemical properties, clay mineralogy, and micromorphology of soil samples investigated and soils were classified by Soil Taxonomy (2014) and WRB (2015) systems.
Calcic, gypsic, argillic, and cambic diagnostic horizons investigated after field and laboratory studies. Typic Calcigypsids, Lithic Torriorthents, Typic Haplogypsids, Typic Haplocalcids, Typic Torrifluvents, Sodic Haplocambids, Typic Calciargids, and Xeric Haplocalcids subgroups were found using Soil Taxonomy (2014) system. Gypsisols, Calcisols, Luvisols, Cambisols, and Regosols reference soil groups identified by WRB (2015) classification system. Developed Alfisols, formed on piedmont plain geomorphic surface in xeric moisture regime. On the other hand, Entisols formed on rock pediments with aridic moisture regime. Soils in aridic moisture regimes were little developed with gypsic horizon, and where calcic horizon was formed, it was near the surface. Moving to the west with increasing humidity, gypsum was leached from the pedon and clay illuviation caused argillic horizon to be formed. Formation of Btk horizon in pedon 9 was attributed to a more paleoclimate. The maximum gypsum content of 44.7 % (gypsiferous soils) was found in soils affected by Quaternary formations and Cretaceous marls, but the maximum calcium carbonate (44 %, calcareous soils) was investigated in soils formed on Neogene conglomerate formations. Moreover, the maximum sodium adsorption ratio (SAR) content (29.2 (mmol(±) L-1)0.5) was determined for soils on unstable surface of alluvial plain. Smectite, vermiculite, illite, kaolinite, and chlorite clay minerals were investigated and smectite to illite ratio increased moving from aridic to xeric moisture regimes that prove the pedogenic source of smectite from weathering of illite. Coating and infilling of calcium carbonate, lenticular and interlocked plates and infillings of gypsum, and clay coatings were observed during micromorphological investigations. Micromorphological observations also showed that gypsum crystals decreased and calcite crystals and thickness of clay coatings increased from aridic to xeric moisture regimes. The minimum amount of gypsum crystals was found in Neogene formations. The results also showed that gypsum pedofeatures are dominant in Cretaceous formations, but calcium carbonate pedofeatures are the main features of Neogene formations. Due to presence of animal voids (channel, regular and star-shaped vughs, chamber, and vesicles), spongy microstructure was formed in agricultural lands.
Results of the research showed the important role of parent material, climate, and geomorphic surface on genesis and development of soils in Bardsir area.

Zeolite is a group of anionic hydrated aluminosilicates with a tridimensional structure which has great implications in remediation of water, sediment and soil resources. The present research aims at physicochemical investigation, clay mineralogy and micromorphology of soils along Rafsanjan-Sarcheshmeh lithotoposequence, southeastern Iran.
The study area starts from mantled pediments, southern west of Rafsanjan and extends to Sarcheshmeh town. Soil moisture and temperature regimes of the area were aridic and mesic, respectively. Topography and geology maps together with Google Earth images were used to investigate different landforms and geological formations in the area. Mantled pediment (pedon 1), rock pediment (pedons 2 and 3) and mountain (pedons 4, 5, 6 and 7) were among dominant landforms recognized in the area under study. Mantled pediment is composed of younger gravel sediments. On the other hand, arkose and tuff are dominant in rock pediment. Besides, mountain geomorphic surface show high proportion of tracky basaltic and doloritic rocks. Seven pedons affected by geological formations on different landforms were described and sampled. Physicochemical analyses together with clay mineralogy and micromorphological observations performed and Soil Taxonomy and WRB were used for soil classification.
Calcic, gypsic, argillic and cambic diagnostic horizons were identified according to field and laboratory investigations. Soils were classified as Typic Haplocalcids, Typic Calciargids, Typic Torriorthents and Typic Haplocambids using Soil Taxonomy. Cambisols, Calcisols, and Regosols were also found according to WRB classification system. Presence of Btk horizon in pedons 4 and 5 was attributed to more available humidity of paleoclimate. Micromorphological observations showed grey radial (fan shape) zeolite crystals with parallel extinction. Calcite coatings, hypocoatings and nodules were among calcium carbonate pedofeatures identified. Lenticular and interlocked plates of gypsum and clay coatings were also observed during micromorphological investigations. Kaolinite, illite, palygorskite and smectite clay minerals were determined. Chabazite with first, second, and third order peaks of 0.64, 0.59, and 0.29 nm and natrolite with first and second order peaks of 0.42 and 0.3 nm together with calcite and quartz impurities were investigated in zeolitic geological formations of the area using X-ray diffractometers. Natrolite was the only zeolite found in soils under study and showed a decreasing trend with distance from zeolitic geological formations. Zeolite in soils of the area seems to be inherited from parent material.
Results of the study showed role of topography and parent material on variability of soil properties in the area.

The Palmer Drought Severity Index (PDSI), which uses hydrometeorological variables to solve a simple water balance equation in the soil and considers the drought or wet conditions as dynamic phenomena, is used for the assessment of drought conditions in many parts of the world. The main goal of this study was to assess the PDSI based on its original assumptions, its regionalized status, using the outputs of already calibrated and validated SWAT model in central regions of Iran. The PDSI was assessed through five 1) original Palmer Index without calibration in which the climate coefficients and the severity equation were derived for Kansas and central Iowa; 2) original Palmer Index in which the coefficients of severity equations were adjusted; 3) the Palmer Index with the calibration of equations in central areas of Iran; 4) the Palmer Index using the soil moisture and potential evapotranspiration from SWAT model; and 5) the Palmer Index using the soil moisture, potential evapotranspiration and runoff from SWAT model. The evaluation was conducted for 17 major basins covering the entire country with a monthly time step for the period 1990-2002. Then, using all five methods, the severity of the drought for 160 sub basins located in central Iran was calculated and evaluated. The results of this study indicated that method 4 provides more acceptable results. Also, the results of this research showed these methods clearly demonstrated (1992) as the wettest year and (2001) as the driest year. The approach used in this study is applicable to regional calibration of Palmer Index and the outputs of other hydrological models.

In order to classify and determine the plant communities in Karkas mountainsides, central Iran, quantitative data of 46 environmental characteristics including climate (12 characteristics), soil (26 characteristics), geology and physiology (8 characteristics), were analyzed based on partial Euclidean distance indicator using minimum variation method. The results showed the clustered separation of studied sites at 68% similarity level with three different growth places. Of these 46 factors, 24 factors (8 climate characteristics and 16 soil characteristics) were effective in this classification at 95% certainty level. Only 24 of these 46 factors were effective in this classification at 95% certainty level. These 24 effective factors were divided into 8 climate and 16 soil characteristics. In another classification, combinational percentage index of 17 plant species were investigated as an effective factor in separating growth place and determining the plant communities. Result of cluster classification indicated that the studied sites cold be classified to 3 habitats.

Gypsiferous Aridisols are of great importance and extent in arid and semi-arid environments. There is a close relationship between soil genesis and landscape positions. This study aimed to determine the genesis and classification of gypsiferous soils and to investigate the relationship between micro-and macro-morphology of gypsum crystals and geomorphic positions in Rafsanjan area. The study area is located in Nough, 30 km north of Rafsanjan with a mean annual precipitation of 60 mm. Seven representative pedons were selected on different geomorphic positions. Physico-chemical, micromorphological, XRD, and SEM observations were performed on soil samples. Rock pediment geomorphic surfaces, that are in fact peripheries of old closed water bodies in central Iran, are the source of gypsum in the area. Large gypsum pendants and microforms of lenticular, vermiform, platy, and interlocked gypsum plates are found in rock pediment. The amount of gypsum and the size of pendants decrease moving down the slope. Lenticular and interlocked gypsum plates are found in a transition of pediment and playa. Puffy ground is observed on the saline surface of playa. Lenticular and vermiform gypsum crystals increase down the slope, but alabastrine gypsum is the most dominant form of gypsum in the playa surface. Large amounts of soft gypsum nodules are found on the rock pediment surface (western slope). In addition, spindle form of gypsum and palycrete bundles are observed in this position. Wind action played a significant role in the genesis and development of soil in rock pediment. A close relationship was found between morphology of gypsum crystals and geomorphic positions.