The magnetic susceptibility of soils in Kohgilouye, Iran

Abstract

. 2006. The magnetic susceptibility of soils in Kohgilouye, Iran. Can. J. Soil Sci. 86: 97-107. Soil magnetic susceptibility (MS) and Fe were examined for several soils on calcareous parent material, reflecting key climatic conditions and drainage classes in southwestern Iran (Kohgilouye Province). Alfisols, in the eastern and northern parts, contained more pedogenic (citrate dithionite extractable) Fe (up to 60 g kg -1 on a minerogenic basis; 70% of total Fe, as determined by lithium tetraborate fusion) and poorly crystalline Fe (up to 6 g kg -1 ammonium oxalate extractable) than the Inceptisols in the southern parts. Soil MS (χ lf ) ranged from 5 to 120 × 10 -8 m 3 kg -1 , with A horizons exhibiting greater values than B horizons, and Alfisols higher than other soils. Pedogenic enhancement of χ lf corresponded with preferential leaching of diamagnetics (primarily carbonates), as well as weathering of primary paramagnetics and neoformation of antiferromagnetics. Frequency dependence of MS (χ fd ), indicating ultrafine superparamagnetics, followed trends similar to χ lf . Sequential heating of well-drained samples, from 25 to 500°C, resulted in enhancement of χ (average of 21%), attributed to the conversion of antiferromagnetics to ferrimagnetics; between 500 and 700°C, χ typically decreased (average of 15%). The χ fd of well-drained soils increased by an average of 5.3 percentiles by 700°C. Gleysolic soils exhibited less weathering (<51% of total Fe), higher proportions of poorly crystalline Fe (>0.15), lower χ lf (<25 × 10 -8 m 3 kg -1 ) and χ fd (<2%), as well as greater average enhancements of χ lf (265% at 500°C) and χ fd (8.4 percentiles at 700°C) on heating.Key words: Calcareous, iron oxides, citrate dithionite, ammonium oxalate, frequency dependence, thermal enhancement Owliaie, H. R., Heck, R. J. et Abtahi, A. 2006. Sensibilité magnétique des sols de Kohgilouye, en Iran. Can. J. Soil Sci. 86: 97-107. Les auteurs ont examiné la sensibilité magnétique (SM) et le fer de plusieurs sols reposant sur une assise calcaire, reflet des conditions climatiques et classes de drainage qu'on retrouve habituellement dans le sud-ouest de l'Iran (province de Kohgilouye). Les alfisols des parties est et nord de la région contenaient plus (jusqu'à 60 g par kg sur la base minérogénique; 70 % du Fe total mesuré par fusion avec du tétraborate de lithium) de Fe pédogénétique (extractible au citrate de dithionite) et de Fe peu cristallin (jusqu'à 6 g par kg extractible à l'oxalate d'ammonium) que les inceptisols de la partie sud. La SM du sol (χ lf ) variait de 5 à 120 × 10 -8 m 3 par kg, les valeurs étant plus élevées dans l'horizon A que dans l'horizon B et dans les alfisols que les sols d'un autre type. L'amélioration de la χ lf par pédogenèse vient principalement de la lixiviation préférentielle des substances diamagné-tiques (des carbonates surtout) ainsi que de l'altération des substances paramagnétiques primaires et de la néoformation de substances antiferromagnétiques. La fonction de la fréquence de la SM (χ fd ), signe...

Magnetic imprints of pedogenesis in Planosols and Stagnic Alisol from Bulgaria

“…Removal of well crystalline phases is typically done by dithionitecitrate-bicarbonate (DCB) extraction (Mehra and Jackson, 1960). Usually a good estimate of the degree of transformation of primary to secondary Fe is considered the ratio Fe d /Fe t , while Fe d reflects the total amount of pedogenic Fe (Owliaie et al, 2006;Schwertmann, 1988). Table 2 gives an overview of the chemical extraction data for Planosols and the Alisol.…”

“…Since the pioneering study of Le Borgne (1955), much research is devoted to establishing a model describing pedogenic magnetic enhancement and its relation to climatic factors (temperature, precipitation) (Fine et al, 1989, Guyodo et al, 2006, Maher and Thompson, 1995, lithology (Shenggao, 2000), topography (Sandgren and Thompson, 1990), and bacterial production of magnetite (Fassbinder et al, 1990, Weber et al, 2006. Studies in this direction are concentrated on soils of Chernozem type (Guyodo et al, 2006, Jordanova et al, 1997, Jordanova et al, 2010, Maher, 1998, Maher et al, 2003, well-drained soils from Iran (Owliaie et al, 2006), Luvisols . However, only few studies deal with soils, subjected to intense long-term water-logging, leading to destruction of iron minerals (Dearing et al, 1995, Sandgren andThompson, 1990;de Jong et al, 2005, Grimley andArruda, 2007).…”

Distribution of iron oxides forms on a transect of calcareous soils, north-west of Iran

“…Primary Fe-bearing minerals (biotite, feldspars, amphiboles, pyroxenes, pyrite etc.) are thermodynamically unstable in soils, eventually being transformed to secondary minerals (Owliaie et al 2005). The weathering of phyllosilicates mainly micaceous minerals is known as one of the important sources of Fe release by several studies.…”

Synergistic co-processing of Red Mud waste from the Bayer process and a crude untreated waste stream from bio-diesel production

“…Samples with a low frequency dependence (<2%) contain virtually no superparamagnetic grains while those exhibiting high dependence (>10%) are dominated by them. 48 The magnetic susceptibility values are shown in Table 6. The standard used was 1% magnetite in aluminum oxide dispersed in an epoxy resin matrix.…”