Moghbeli Z.; S. Sanjari; E. Adhami
Abstract
Introduction: In sustainable agriculture, it is essential to know soil various characteristics for increasing the soil productivity. The relationship between soil and geomorphology in arid and semi-arid regions has been considered by many researchers. Faryab plain is located in arid region of Kerman ...
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Introduction: In sustainable agriculture, it is essential to know soil various characteristics for increasing the soil productivity. The relationship between soil and geomorphology in arid and semi-arid regions has been considered by many researchers. Faryab plain is located in arid region of Kerman Province and has diversity in geomorphic positions and parent materials. No previous study has been conducted in this region. Therefore, the objectives of the present research were 1) to study the genesis and development of soils related to different geomorphic surfaces in Faryab region, 2) to study the physicochemical properties, clay mineralogy and micromorphology of soils, and 3) to classify the soils according to Soil Taxonomy (ST) (2014) and World Reference Base (WRB) (2015) systems and compare them.
Materials and Methods: Faryab region with a mean elevation of 630 m above sea level is located in Kerman province, south-eastern of Iran. Mean annual rainfall and temperature of the area are 160 mm and 23.8 oC, respectively. Soil temperature and moisture regimes of the area are thermic and aridic, respectively. From geological point of view, the studied area is a part of west and south west zones and Flysch zone of east of Iran. Ten representative pedons on different geomorphic units including hill, alluvil-colluvial fan, alluvial plain, and lowland were selected, sampled, and described. Routine physicochemical analyses, clay mineralogy, and micromorphological observations performed on soil samples. Soil pH, texture, electrical conductivity, calcium carbonate, Na, Ca, Mg, cation exchangeable capacity and gypsum were identified. Eight samples were selected for clay mineralogy investigations. Four slides including Mg saturated, Mg saturated treated with ethylene glycol, K saturated, and K saturated heated up to 550 oC were analyzed. A Brucker X-Ray diffractometer at 40 kV and 30 mA was used for XRD analyses. Undisturbed soil samples from some representative pedons were selected for micromorphological observations. A vestapol resin with stearic acid and cobalt as hardener was used for soil impregnation. A Lite petrographic microscope was used for micromorphology investigations.
Results and Discussion: The results of the present study indicated that the soils with more evolution were located on the geomorphic surfaces of the lowland and alluvial plain and the soils with lower development on the hill and alluvil-colluvial fan. The most important pedogenic processes of the soils were the eluviation of salt, gypsum, calcium carbonate as well as clay, and the formation of calcic, gypsic, petrogypsic and natric horizons. The soils of the region were classified using ST as Aridisols with three suborders of Argids, Calcids and Gypsids and classified according to the WRB as three soil reference groups of Solonetz, Gypsisols and Calcisolos. A new subgroup of Calcic Natrigypsids is suggested for inclusion to ST for the soils with aridic soil moisture regime and three horizons of gypsic, calcic and natric. The WRB system, due to its flexibility in the use of principle and supplementary qualifiers, prepare a better qualification than ST for the soils of the region. According to mineralogical results, the observed minerals consisted of illite, palygorskite, chlorite, smectite, kaolinite, vermiculite and quartz. The highest amount of palygorskite was observed in the gypsic horizons of hill and alluvil-colluvial fan. By moving to the central part of the plain (lowland), the amount of palygorskite was greatly reduced and the amount of smectite was increased. Two origins of inheritance and transformation (illite and palygorskite) are suggested for the occurrence of smectite in the soils. Due to the lack of the conditions for the formation of kaolinite, illite and chlorite, these minerals are inherited from parent materials. SEM observations suggested a pedogenic pathway for the occurrence of large amounts of palygorskite in the soils of the region. Calcareous and gypsiferous media seems to prepare a favorite environment for the pedogenic formation and stabilizing of this mineral in the studied soils. Coating and infilling of gypsum and calcite crystals in voids and channels, clay coating along chanels as well as Fe and Mn oxide nodules were among the common pedofeatures observed in the thin sections of the studied soils. Occurrence of variable habits of gypsum crystals in different geomorphic surfaces suggested a dynamic soil environment. Larger lenticular gypsum crystals were found in the soils with lighter texture located on more stable geomorphic surfaces.
Conclusion: Different geomorphic situations in the region affected the development and evolution, physicochemical properties, clay mineralogy, micromorphology and soil classification and caused the differences in these characteristics in the Faryab region.
Farsila Mahmoudian; Ali reza Karimi; Amir Lakzian
Abstract
1- Abdelkhalik Ibrahim M.A. 2011. Argillic horizons and clay-sized particles - an alternative interpretation of their dynamics in sola development and across catenas. Ph.D. Thesis, Iowa State University, 127p.
2- Bayat O., Karimzadeh H.R., Karimi A., Eghbal M.K., and Khademi H. 2013. Pedogeomorphic ...
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Mahmoud Enjavinejad; Hamidreza Owliaie; Ebrahim Adhami
Abstract
Introduction: Magnetic susceptibility measurements can serve a variety of applications including the determination of changes in soil-forming processes, the study of parent material effects, understanding sedimentation processes, soil drainage conditions, and even the separation and identification of ...
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Introduction: Magnetic susceptibility measurements can serve a variety of applications including the determination of changes in soil-forming processes, the study of parent material effects, understanding sedimentation processes, soil drainage conditions, and even the separation and identification of soil delineations. The technique is especially attractive since it is relatively rapid, non-destructive, and can be applied to both intact and disturbed samples of soils. Magnetic susceptibility is defined as the ratio of the total magnetization induced in a sample relative to the intensity of the magnetic field that produces the magnetization. Iron oxides are the most abundant of the metallic oxides in most soils; they are present in all climatic regions, in several mineral forms, and at variable concentrations. Typically, selective dissolution techniques are used to quantify the relative proportion of Fe oxides. Due to the large contribution of iron-bearing minerals to magnetic susceptibility, their presence in most soils, and the effects of the biophysical environment on them, pedologists have been paying growing attention to magnetic susceptibility as a means to understand soil and landscape processes. The effects of topography on χ were studied for example by many workers. They found that soil susceptibility changes with the position of a soil profile on a slope. Texture and drainage class assumed to be the main reasons. The soils of the Beshar Plain formed on the relatively same parent materials and are mainly affected by topography and land use. The objective of this study was to examine the role of topography and land use on pedogenic processes and their relation to soil χ, as well as, profile distribution of secondary Fe oxides, and the χ profiles.
Materials and Methods: This study was conducted on the Beshar Plain, Kohgilouye Province, in southwest of Iran. Physiographically this plain comprises hill, piedmont plain, river traces, and plateau. Eleven representative pedons were dug along a transect crossing the main physiographical units. Five pedons demonstrated aquic soil moisture regime. The mean annual temperature and precipitation at the site was 14.7°C and 800 mm, respectively. Soil moisture and temperature regimes of the study area were xeric and thermic, respectively. The soils were classified according to soil taxonomy and WRB. The soil pH was measured in a saturation paste and electrical conductivity (EC) in a saturation extract. Cation exchange capacity (CEC) was determined using sodium acetate (NaOAc) at a pH of 8.2. Soil texture was determined using the pipette method. Calcium carbonate equivalent (CCE) was measured by acid neutralization. Organic carbon was determined by wet oxidation method. Pedogenic Fe (Feo) and pseudo-total Fe (Fen) were extracted with the CBD method and HNO3, respectively.The magnetic susceptibility of bulk 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.
Results and Discussion: The soils were classified as taxonomic orders of Entisols, Mollisols, Inceptisols and Alfisols, according to the world reference base for soil resources (WRB) as reference soil groups of Kastanozems, Regosols, Gleysols, Luvisols, Fluvisols and cambisols. The dominant pedogenic processes in the soils were the accumulation of organic matter, the leaching of carbonates, and formation of calcic horizons, the mobilization of clay and development of argillic horizons. The results indicated that the soils are affected mainly by topography, drainage class and land use. Most pedons exhibited maximum of χ at the soil surface, suggesting preferential loss of diamagnetic components, as well as more pedogenic formation of antiferromagnetic minerals. Magnetic measurements showed that the χ values of aquic soils were much lower than those of non-aquic soils (43%). The highest value of χ was noted in pedons which are located on stable physiographic units and the lowest belong to those which are located on river lower terraces. Fed and fen was also positively correlated with χ in the soils studied. Aquic condition also decreased Fed and Fed/Fen, 44 and 65 percent, respectively with no clear effect on Fen. Low to medium amounts of χfd in the studied soils indicated that superparamagnetic gains are not too dominant in the soils. Higher values of χfd were typically observed in the A horizons than at depth, suggesting a greater proportion of ultrafine grains at soil surface. A positive correlation existed between χfd and χ in the soils.
javad seyedmohammadi; leila esmaeelnejad; hassan ramezanpour; kamran eftekhari
Abstract
Introduction: Paddy soils are important and the base of agriculture in Guilan province. It is necessary to recognize these soils for understanding of their limitations and optimum use. Unsaturated soil submerging is the cause of collection of chemical and electrochemical process that has significant ...
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Introduction: Paddy soils are important and the base of agriculture in Guilan province. It is necessary to recognize these soils for understanding of their limitations and optimum use. Unsaturated soil submerging is the cause of collection of chemical and electrochemical process that has significant effects on soil fertility. Eh, rH and pH are important indexes that are used to investigate oxidation and reduction condition in submerged soils and have abundant effects on activity and sorption rate of nutrients. Decrease of Eh and rH in poorly drainage of paddy soils affects availability and solubility of nutrient. Different Fe forms are used for analysis of soils evolution trend and submerging influences on changes of Fe forms. The aim of the present study was conducted to investigate the effect of redox potential changes on soil characteristics and analysis of soils evolutional trend in different physiographic units.
Materials and Methods: The study area with 40000ha (at the east of Rasht city) is located between 49° 31' to 49° 45' E longitude and 37° 7' to 37° 27' N latitude in North of Guilan Province, Northern Iran, in the southern coast of the Caspian sea with different water table depth. The climate of the region is very humid with the mean annual precipitation of 1293.6 mm. The mean annual temperature is 15.8°C. The soil moisture and temperature regimes are Aquic, Udicand Thermic, respectively. The parent materials are derived from river sediments. The soils formed on the plateaues and upper terraces, river alluvial plain and lowland physiographic units were classified as Inceptisols and the soils formed on coastal plain physiographic unit as Entisols. Air-dried soil samples were crushed and passed through a 2mm sieve. Particle-size distribution, organic carbon and cation exchange capacity were determined by hydrometric, wet oxidation and ammonium acetate methods, respectively. Eh by Eh electrode, total iron, free iron and amorphous iron were determined using nitric acid, dithionite-citrate-bicarbonate and ammonium oxalate methods, respectively. The means of different Fe forms values compared through LSD test.
Results and Discussion: It can be seen especial morphological and physicochemical characteristics in studied paddy soils with high groundwater table due to artificial submerging in rice growing seasonDifferent Fe mottles such as orange mottles include lepidocrocite mineral was observed in studied soils. Low redox potential with average 145/7mV and rH with average 19.6 in lowland and coastal soils implicate intense reduction condition. In lowland soils Eh was lower than other units and it was lower in top horizons than to sub horizons in all of units. Eh index had inverse relationship with organic matter, because of high organic matter amount caused high activity of anaerobic micro-organisms, increase of iron reduction and reduction soils degree decrease. rH index amounts showed that studied soils had reduction condition and presence of brown iron and black manganese minerals proved this condition. CEC was high in top soil of physiographic units due to high amount of organic matter and clay content. Clay particles in plateaues were lower than other units because of alteration and suitable aeration and showed high evolution in these soils. Clay coatings were not observed due to high ground water table and its alternative fluctuation. Results showed amorphous iron in surface horizons with average amount of 24.3g kg-1 was higher than subsurface in all soils and had positive correlation with organic matter, because of high activity of anaerobic micro-organisms that prevent from transformation of amorphous iron to crystallized iron, therefore amorphous iron amount increased in presence of organic matter. Pedogenic iron was high in A and B horizons with regard to BC and C horizons due to aeration and weathering. In lowland and coastal land Fed was lower than plateaues and upper terraces and river alluviums units because of ground water presence and its alternative fluctuation. Fed-Feo index showed crystallized iron oxides, high amount of Fed-Feo index proved soils evolution and high weathering. Feo/Fed ratio was related to amorphous pedogenic iron and high amount of this index showed few evolution of soil. Fed/Feo and Fed-Feo indexes indicated the lower rate of crystallized iron with average 6.8g kg-1 in lowland and coastal soils and implicated the lower evolution of these units' soils, due to higher surface groundwater and its more fluctuation than soils of plateaues, upper terraces and river alluviums unites with average amount of crystallized iron 15/8g kg-1.The comparison of different Fe forms using LSD method showed significant difference at the 0.01 level for different Fe forms values in different physiographic units.
Conclusion: Submerging, high groundwater table and severe fluctuation caused noticeable changes in morphological, physical, chemical and electrochemical properties of studied paddy soils. Noticeable organic matter amount added to soil and their burial by puddling operation and slow decomposition were effective factors in redox potential changes of studied wet soils. In equal anaerobic condition, more organic matter caused to decrease redox potential in surface horizons of soils with aquic condition and reverse, lower organic matter caused increasing in redox potential. lower amount of Eh and rH proved severe reduction condition in lowland. Investigation of Fed-Feo and Feo/Fed showed that their amount in lowland and coastal land were lower than plateaus and river alluviums, therefore lowland and coastal soils had lower evolution. Mean comparison of different Fe forms values using LSD method showed significant difference at the 0.01 level for different Fe forms in different physiographic units.
N. Sadri; H.R. Owliaie; E. Adhami; M. Najafi Ghiri
Abstract
Introduction: The optimum and sustainable use of soil is only possible with a correct and complete understanding of its properties. Potassium (K+) is an essential element for plant growth and is a dynamic ion in the soil system and its importance in agriculture is well recognized. According to increasing ...
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Introduction: The optimum and sustainable use of soil is only possible with a correct and complete understanding of its properties. Potassium (K+) is an essential element for plant growth and is a dynamic ion in the soil system and its importance in agriculture is well recognized. According to increasing order of plant availability, soil K exists in four forms: mineral (5000-25000 ppm), nonexchangeable (50-750 ppm), exchangeable (40-600 ppm), and solution (1-10 ppm). K cycling or transformations among the K forms in soils are dynamic. The objectives of the present research were to study the relationship between different forms of potassium and clay mineralogy as well as soil evolution of 14 surface soil samples from some selected locations of Fars Province.
Materials and methods: Fars provinces, with an area of 122000 km2 located in southern Iran. The elevation varies from 500 m to 4400 m above mean sea level. Mean annual precipitation ranges from about 350 mm to 850 mm. Mean annual temperature ranges from 10°C to 24°C. According to Soil Moisture and Temperature Regime Map of Iran, the soils comprise xeric, and ustic moisture regimes along with mesic, thermic and hyperthemic temperature regimes. Based on the previous soil survey maps of Fars province, 14 surface soil samples were collected. Routine physicochemical analyses and clay mineralogy were performed on soil samples. Soil reaction, texture, electrical conductivity, calcium carbonate, and gypsum were identified. Soluble potassium, exchangeable potassium, non exchangeable potassium, and mineral potassium were measured. The amounts of K forms in each sample were determined. Total K was determined following digestion (110°C) of soil with 48 % HF and 6 M HCl. Water soluble K was measured in the saturated extract. Exchangeable K was extracted with 20 ml 1.0 M NH4OAc (pH 7.0) for 5 min. Nitric acid-extractable K was measured by extraction of a soil sample with boiling 1.0 M HNO3 for 1 h. Potassium was measured on all filtrated extracts by flame photometer. The content of clay minerals was determined semi-quantitatively, using peak areas on the diffractograms of ethylene glycol solvated specimens.
Results and discussion: The soils are all calcareous (average of 43% calcium carbonate equivalent) with relatively high clay contents (average of 34 %). The different forms of K including water soluble, exchangeable, HNO3-extractable, and mineral K are also relatively high in the studied soils. Mineralogical analysis indicated that smectite, illite, palygorskite and chlorite, were the major minerals in the clay fractions. The results also showed that exchangeable, non-exchangeable and total potassium were in the range of 230 to 436, 282 to 1235, and 2312 to 9201 mg/kg-1, respectively. The soils categorized into three groups based on the soil evolution, clay mineralogy, and total potassium. Well developed soils (Alfisols), slightly developed soils (Aridsols and Inceptisols), and non developed soils (Entisols), were categorized in groups of1, 2, and3. Except for soluble K, maximum of the other potassium forms were observed in group 1. Moreover, there was a high correlation between allpotassium forms andillite content, except for soluble potassium. Mineralogical results revealed that smectite and illite were the major clay minerals in Alfisols resulting high amount of available potassium. The differences among the soil groups in terms of clay percentages may be the results of differences in parent material. K concentration is greater in soils with higher content of calcium carbonate and this is resulted in the greater leaching of K in these soils. This is in consistent with the finding of the other authors, who concluded that calcite and gypsum have a positive effect on the concentration of K in soil solution and leaching of this element from soil.
Conclusion: The results of the present study indicated that the arid and semiarid soils of southern Iran have a relatively high content of K pools. Exchangeable and HNO3-extractable K exist in equilibrium with each other, but the exchangeability of HNO3-extractable K is greater in soils dominated with illite and montmorrilonite than other soils dominated with chlorite and palygorskite. It found that calcium carbonate content had a negative effect on different soil K pools except for water soluble K. The relationship obtained in this study will be allowed determination of soil K pools from clay mineralogy and chemical and physical properties such as exchangeable K, clay content and calcium carbonate content.
Mohammad Ghasemzadeh Ganjehie; Ali reza Karimi; Ali Zeinadini; Reza Khorasani
Abstract
Introduction: Playa is one of the most important landscapes in arid regions which covers about 1% of the world's total land area. Study of playas is important from different points of view especially pedology, sedimentology, mineralogy, environmental geology, groundwater and surface water chemistry. ...
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Introduction: Playa is one of the most important landscapes in arid regions which covers about 1% of the world's total land area. Study of playas is important from different points of view especially pedology, sedimentology, mineralogy, environmental geology, groundwater and surface water chemistry. More than 60 playas have been identified in Iran. Considering the fact that playas and surrounding landforms are important archive of landscape evolution and paleoenvironmental variations, it seems that less attention has been paid to them so far. Soils are known as indicators of the landscapes evolution. Previous studies in arid regions of Iran imply different periods of deposition and soil formation in playa and alluvial fans or pediments. Bajestan playa is one of the known playa in northeastern Iran, and the largest clay flat exists in this playa. There is no information on the soils and their evolution in Bajestan playa. The objective of this study were to 1) identify the soils in different landforms along a transect from alluvial fan to clay in Bajestan playa 2) determine the morphological, micromorphological and mineralogical characteristics of these soils 3) determine the periods of soil and landform evolution and 4) comparison of soils evolution of the study area to other arid regions of Iran.
Material and Methods: The study area of approximately 20000 hectares is located in southeastern of KhorasanRazavi province. The climate of the study area is hot and dry with mean annual temperature and rainfall of 17.3 °C and 193 mm, respectively. Soil moisture regime is aridic with subdivisions of weak aridic and soil temperature regime is thermic. Firstly, landforms and geomorphic surfaces of the study area were recognized based on Google Earth images interpretations and field observations. Four main landforms were recognized in the study area. The landforms from north to the south of the study area were alluvial fan, intermediate alluvial fan- clay flat, pediment and clay flat. Considering the diversity of geomorphic units, 11 soil profiles were described and diffrenet soil layers and horizons were sampled. Undisturbed soil samples were taken micromorphological studies. Some horizons were selected for clay mineralogy analysis. The mineralogy of clay fraction was determined using X-ray diffraction method.
Results and discution: All studied soils except the profiles in the pediment were classified in the Aridisols order. There were two geomorphic surfaces in alluvial fans. In the first geomorphic surface a soil with the Bk horizon buried a soil with red Btk horizon. In the second geomorphic surface, it seems that the erosion has been removed the overlying soil. The Bk horizon showed the maximum soil development in the clay flat and intermediate alluvial fan-clay flat landforms. Clay coating on sand in thin section was the evidence of clay illuviation in Btk horizon. Carbonate nodules associated with clay coating are the compound pedofeature in Btk horizon. These evidences reflect polygenetic nature of the soils and different period of climate change and soil formation. Smectite, mica, chlorite and palygorskite are the clay minerals in the studied soils. Similar to soils in arid regions of Iran, palygorskite was found in Bk, Bt and Bz horizons. The existence of Bk horizon in overlying soils, buried Btk horizon, removal of surface horizon in alluvial fan are the evidences of regressive and progressive of pedogenic processes in the study area. Btk horizon represents a warm and wetter and Bk horizon indicates a relatively wetter period in comparison to present time.
Conclusion: Btk was the most developed horizon in the study area that occurred as buried paleosol in alluvial fan. Bk, Bw, By and Bz were the common horizon in other landforms. Clay coating and red color of Btk horizon might seem as indicators of hot and humid conditions in the past, during the argillic horizon formation. Covered carbonate nodules with clay coating can also be mentioned as sign of a hot and wet period which is suitable for clay illuviation and weathering after a period of carbonate accumulation. The buried Btk horizon under alluvial layers in the alluvial fan indicates that after apedogenic period, alluvial processes have been responsible in burying this horizon. Bk horizon in overlying soil of all landforms represents a less intense period of soil formation. The dominant clay minerals in the study area were Illiite, cholorite, kaolinite, and palygorskite. The sequence of Bk and Btk horizons in this research and the occurrence of these soils in central, eastern and northeastern Iran imply the similar pedogenetic conditions in arid regions of Iran.
M. Zarinibahador; - K. Nabiollahi; M. Norouzi
Abstract
Introduction: Spatial variation of soil properties is significantly influenced by numerous environmental factors such as landscape features, including position, topography, slope gradient and aspect, parent material, climate and vegetation. Soil properties vary spatially in south- and north-facing hill ...
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Introduction: Spatial variation of soil properties is significantly influenced by numerous environmental factors such as landscape features, including position, topography, slope gradient and aspect, parent material, climate and vegetation. Soil properties vary spatially in south- and north-facing hill slopes. This factor (different slope aspects) can affect the distribution of soil organic matter, the presence or absence of a layer, pH, nutrient levels, soil mineralogical and micromorphological properties. Topographic factors such as the orientation of the hill slope and the steepness of the slope affect microclimate, vegetation establishment, water movement and erosion. Aspect and slope control the movement of water and materials in a hill slope and contribute to differences in soil properties. Temperature, precipitation and climate vary with elevation and influence pedogenic processes. Accelerated rates of weathering and soil development were found to occur in soils on south-facing slopes. Slopes with a south aspect are dominated by stone and bare soil patches, while slopes with a north aspect are dominated by biotic components. Northern slopes have higher productivity and species diversity compared to Southern slopes. Slope aspect has a significant effect on the composition, species richness, structure and density of plant communities, differed significantly between North- and South- facing slopes.
Materials and Methods: In the present study, the effects of two slope aspects on some soil properties and soil evolution was investigated in Northern Rostam Abad region in the Guilan Province. Five profiles in Southern hill slope(South-facing hill slopes) and five profiles in Northern hill slopes(North-facing hill slopes) with 40% slope and same parent material (basaltic andesite) and same plant cover were dug. The elevation of two slope aspects was 240 meters from the sea level. Average annual temperatures and precipitation are16 degrees centigrade and 1359 mm, respectively. Thus, the soil moisture and temperature regimes are udic and thermic, respectively. The physical and chemical analysis were carried out on soil samples including particle size distribution, bulk density, pH, organic carbon, total nitrogen, available phosphor and cation exchange capacity. This study was done in a completely randomized design several observational with five replications. The total of 34 soil samples were collected in the two slope aspect of the profile and all samples were tested and statistical analyzed. For the micromorphological study, thin sections were prepared from undisturbed samples. The samples were impregnated with polyester resin and later sectioned. The thin sections were prepared and analyzed in petrographic microscope equipped with polarized light.
Results and Discussion: The results of multivariable analysis of variance (MANOVA) and Hotteling's T2 showed that there is significant different in soil properties between two hill slopes(p≤0.01). Also, the results of t-test showed the values of pH, content of sand, sand to clay ratio and available phosphorous significantly was higher in Southern hill slope in comparison with Northern hill slope(p≤0.01). Whereas, clay content and cation exchange capacity significantly were higher in Northern hill slope in comparison with Southern hill slope(p≤0.05). Also observed micromorphological studies showed biological activity was stronger in Northern hill slope in comparison with Southern hill slope. Properties observed in thin sections of Northern slope aspect include fungal hyphae, spherical and ellipsoid excrement of microorganisms in root residual (related to oribatid mites) which indicated stronger biology in Northern slope aspect soils as compare to Southern slope aspect soils. Also, more accumulates* of clay inside voids, nodules, fragmented of coating of well-oriented, micro laminated, reddish-brown clay, chamber voids in Northern slope soils toward Southern slope soils were observed. B-fabricobserved in Northern hill slope soils is stipple speckled in surface horizons and in subsurface horizons is grano-striated and stipple speckled and b-fabric observed in Southern hill slopes soils in surface horizons and subsurface horizons is stipple speckled.
Conclusion: Higher content of clay, Cation exchange capacity, Accumulation of clay in pores, Fragments of clay coating (papule), chamber pores, Fe/Mn oxide nodule and micro-laminations in Northern hill slope and higher values of pH, higher content of sand, sand to clay ratio and available phosphorous, lithorelict in Southern hill slope showed that weathering was higher in Northern hill slope in comparison with Southern hill slope. Generally, Southern hill slope had less developed soils (Entisols and Udorthents great group) and Northern hill slope had high developed soils (Alfisols and Hapludalfs great group).
Sh. Nosratipoor; M. Nael; Mohsen Sheklabadi; A.A. Sepahi Garo
Abstract
To determine the origin of heavy metals, the effects of parent materials, soil genesis, and human activities on the content and distribution of selected metals in soils near Mofateh Martyr powerhouse, Hamedan, were assessed. Six types of parent materials including shale, schist, limestone, alluvial ...
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To determine the origin of heavy metals, the effects of parent materials, soil genesis, and human activities on the content and distribution of selected metals in soils near Mofateh Martyr powerhouse, Hamedan, were assessed. Six types of parent materials including shale, schist, limestone, alluvial plain, alluvial terraces and fan deposits were identified and soil genesis were studied. Total content of Cd, Cu, Mn, Ni, Zn, Pb, Fe were determined in soil horizons and parent materials. Concentration of the metals in four different chemical phases, including acetic acid extractable, reducible, oxidizable and residual fractions, was determined with four-step sequential extraction procedure. Soil development is limited in the studied region so that the discrepancy between solum and parent material in terms of heavy metal content is not great in general. Calcareous soils and limestone have the lowest amount of copper, manganese, nickel, zinc, lead and iron. Independent of soil types and parent materials, most of the heavy metals, except Mn, were present in the residual fraction. The concentration of Mn in all profiles is highest in reducible fraction. Low degree of soil development and the prevalent presence of metals in residual fraction show the influential role of parent materials in controlling metal concentration and distribution; pedogenic processes have minor effects. The role of human activities is limited for most of the selected metals; however, the tangible presence of Pb and, in some cases, Cd in acetic acid extractable fraction, reflects the impact of human activities on the concentrations of these two metals.
