پذير رفتاري مغناطيسي مهم ترين گروه هاي بزرگ خاك هاي مسير اصفهان- چلگرد و نقش برخي خصوصيات خاك بر آن

چكيده انگليسي :

Magnetic Susceptibility of Major Soil Great Groups along the Isfahan Chelgerd Transect as Affected by Selected Soil Properties Elham Mogharehabed emogharehabed@yahoo com January 14 2014 Department of Soil Science Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi H Khademi hkhademi@cc iut ac ir Abstract Magnetic susceptibility approach as a simple relatively inexpensive fast and non destructive method has been used in a wide range of rocks and soils studies in the past few decades Although the measurement of magnetic susceptibility is simple but interpretation of results is complicated and typically requires knowledge of the effective factors controlling it This study aimed to examine the vertical distribution of magnetic susceptibility to determine the changes in magnetic susceptibility after removing some of the effective factors and to estimate minerogenic magnetic susceptibility in soils path along the Isfahan Chelgerd transect having an arid to semi arid climate Major soil great groups along the transect including 7 pedons in the Isfahan region with an aridic soil moisture regime and a thermic temperature regime and 8 pedons in the ChaharMahalVaBakhtiari region with a xeric moisture regime and a mesictemperature regime were selected and sampled to the depth of 150 centimeters Samples were taken for laboratory analysis from70 genetic horizons belongingto 15 profiles To determine the effect of diamagnetic materials on magnetic susceptibility desalination and degypsification treatments were carried out on soils from Isfahan using successive washing with distilled water and organic matter was removed from soils of ChaharMahalVaBakhtiari using H2O2 30 Decalcification treatment using the buffer solution of acetic acid sodium acetate with pH 5 and removal of iron treatment by citrate dithionite bicarbonate solution were performed on all the soils The results showed that the organic matter usually added to the soil surface as well as salinity gypsum and carbonates due to their diamagnetic behavior and also because of their mobility in soil would influence the magnetic susceptibility They normally reduce the amount of magnetic susceptibility through dilution The effect of desalination treatment on the increase of magnetic susceptibility was not statistically significant indicating that the contribution of soil salinity to magnetic susceptibility was not significant due to the small mass of soils occupied by soluble minerals Also iron removal resulted in the instability andelimination of maghemite and thus reduced the magnetic susceptibility Due to the lack of discontinuity the vertical distribution of magnetic susceptibility in pedons fromChaharMahalVaBakhtiary is uniform In contrast soils from Isfahan showed great changes in magnetic susceptibility with depth which could be attributed to their non uniform parent materials and anthropogenic influence Unexpectedly the amount of magnetic susceptibility after the removal of carbonates as a measure of soil development was higher in soils from Isfahan as compared to those fromChaharMahalvaBakhtiari The removal of iron shows that the high magnetic susceptibility of soils in Isfahan is not the result of soil development but also it depends on differences in mineralogy of parent material in the studied landscapes While a great portion of magnetic susceptibility in ChaharMahalvaBakhtiary soils seems to originate from pedogenically formed minerals such as maghemite In future studies investigators are encouraged to remove the effect of each controlling factor to more satisfactorily determine the real role of soil components on soil magnetic susceptibility to be used in soil development interpretation To remove the effects of diamagnetic materials and to compare real changes minerogenic basedmagnetic susceptibility should be calculated Key Words Magnetic susceptibility Maghemite Diamagnetic materials magnetic properties Salinity Gypsum Carbonats Organic

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پذير رفتاري مغناطيسي مهم ترين گروه هاي بزرگ خاك هاي مسير اصفهان- چلگرد و نقش برخي خصوصيات خاك بر آن

مگهميت , مواد ديامغناطيسي , پارامترهاي مغناطيسي , شوري , گچ , كربنات ها