Iron oxides in tropical soils on various parent materials

Wiriyakitnateekul, Wanpen; Suddhiprakarn, A.; Kheoruenromne, Irb; Smirk, Michael; Gilkes, Robert

doi:10.1180/claymin.2007.042.4.02

Cited by 20 publications

(18 citation statements)

References 33 publications

(69 reference statements)

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“…Similar observations were made in earlier studies on highly weathered Brazilian, Australian and Indonesian soils (Fontes and Weed 1991; da Motta and Kämpf Trace elements association with soil iron oxides Soil Research1992; Singh and Gilkes 1992;Prasetyo and Gilkes 1994). The MCD from XRD line-broadening indicated that goethite crystals had a smaller size than associated hematite, as is generally observed for tropical soils (Fontes and Weed 1991;Singh and Gilkes 1992;Prasetyo and Gilkes 1994;Muggler et al 2001;Trakoonyingcharoen et al 2006;Wiriyakitnateekul et al 2007). Aluminium substitution in Fe oxides increases structural strain, slows the rate of crystal growth and reduces crystal size (Schwertmann 1988 (Fontes and Weed 1991).…”

Section: Mineralogical Properties Of Fe Oxide Concentratessupporting

confidence: 70%

“…Hematite and goethite were the main constituents of Fe oxide concentrates from these Thai red soils (Trakoonyingcharoen et al 2006;Wiriyakitnateekul et al 2007). Maghemite, anatase and rutile were present in small amounts in most of the Fe oxide concentrates in the study.…”

Section: Mineralogical Properties Of Fe Oxide Concentratesmentioning

confidence: 97%

“…Singh and Gilkes (1992) suggested that some portions of the Co, Cr, Cu, Mn, Ni and Zn, associated with Fe oxides in soils from south-western Australia, may be present within the structure of the two commonly occurring Fe oxides-goethite and hematite. A close association of trace elements, including Mn, Ni, Cr and vanadium (V), with Fe oxides exists in Thai soils (Wiriyakitnateekul et al 2007). The nature of the association between trace elements and Fe oxides in soils has not been established for several other environmentally important trace elements.…”

Section: Introductionmentioning

confidence: 99%

“…The distribution of Fe oxides in soils is also varied, ranging from a uniform distribution throughout the soil matrix to concentrated forms in segregations such as concretions and mottles (Schwertmann 1991;Singh and Gilkes 1992;Wiriyakitnateekul et al 2007). Because of the variability of the chemical environment in soil during the precipitation of Fe oxides, and their ability to incorporate other trace elements into their structures, Fe oxides are an important source and sink of environmentally significant trace elements.…”

Section: Introductionmentioning

confidence: 99%

“…Trace elements are commonly associated with Fe oxides in soils; however, it is not known whether these elements occur within a separate phase or substitute for Fe 3+ in the structure of Fe oxides (Singh and Gilkes 1992;Trolard et al 1995). The substitution of aluminium (Al) in soil goethite and hematite has been well established; however, the association of trace elements has received only limited attention (Fontes and Weed 1991;da Motta and Kämpf 1992;Singh and Gilkes 1992;Trakoonyingcharoen et al 2006;Wiriyakitnateekul et al 2007). Singh and Gilkes (1992) suggested that some portions of the Co, Cr, Cu, Mn, Ni and Zn, associated with Fe oxides in soils from south-western Australia, may be present within the structure of the two commonly occurring Fe oxides-goethite and hematite.…”

Section: Introductionmentioning

confidence: 99%

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Association of trace elements and dissolution rates of soil iron oxides

et al. 2014

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Abstract. In this study, nine Oxisols and five Ultisols from Thailand were used to determine the association of major and trace elements with iron (Fe) oxides. The Fe oxides were concentrated and the association of elements (Al, Ca, Cu, Cr, Mg, Mn, Ni, Pb, P, Si, V, Ti, Zn) with Fe was evaluated using batch dissolution in 1 M HCl at 208C. The dissolution behaviour of Fe oxide concentrates was determined using batch dissolution and flow-through reactors. In addition to Fe, both Al and Ti were present in significant amounts in the Fe oxide concentrates. Manganese was the most abundant trace element, and Cu, Zn, Pb and As concentrations were <250 mg kg -1 in most samples. The dissolution behaviour of Fe-oxide concentrates indicated that Al, Cr and V were mostly substituted for Fe 3+ in the structure of goethite and hematite. A significant proportion of Mn, Ni, Co, Pb and Si was also present within the structure of these minerals. Some Mg, Cu, Zn, Ti and Ca was also associated with Fe oxides. The dissolution kinetics of Fe oxide concentrates was well described by three models, i.e. the cube root law, Avrami-Erofejev equation and Kabai equation, with the dissolution rate constants (10 3 k) corresponding to the three models ranging from 0.44 to 6.11 h -1 , from 1.01 to 4.40 h -1 and from 0.03 to 4.12 h -1 , respectively. The k constants of Fe oxide concentrates in this study were significantly and negatively correlated with the mean crystal dimension derived from [110] and [104] of hematite, the dominant mineral in most samples. The steady-state dissolution rate of a soil Fe-oxide concentrate (sample Kk) was substantially higher than for synthetic goethite under highly acidic conditions; this is possibly due to the greater specific surface area of sample Kk than the synthetic goethite.Additional keywords: acid dissolution, batch method, Fe oxide concentrate, non-stirred flow through reactor method, total element concentration, tropical red soils.

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Section: Mineralogical Properties Of Fe Oxide Concentratessupporting

confidence: 70%

Section: Mineralogical Properties Of Fe Oxide Concentratesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Association of trace elements and dissolution rates of soil iron oxides

et al. 2014

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Dominance of goethite over hematite in iron oxides of mineral dust from Western Africa: Quantitative partitioning by X‐ray absorption spectroscopy

et al. 2014

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This paper reports on the X-ray absorption analysis of samples of mineral dust emitted from or transported to Western Africa. We found that iron oxides account, by mass, for 38% to 72% of the total elemental iron. They are composed of minerals in the Fe(III) oxidation state: goethite (FeO·OH) and hematite (Fe 2 O 3 ). The apparent fraction of iron oxide attributed to goethite is higher than hematite regardless of the source region from which the dust originated. The goethite percent content of iron oxides is in the range 52-78% (by mass), the highest values being measured for dust originating in the Sahel. The limited number of samples analyzed and the sample-to-sample variability prevent us from concluding firmly on the regional variability of the goethite-to-hematite ratio. Based on the experimental data on mineralogical composition and on concurrent measurements of the number size distribution, the optical properties of mineral dust have been calculated in a Mie approximation for homogeneous spherical particles. At 550 nm, the single-scattering albedo ω 0 ranges between 0.89 and 0.93, the asymmetry factor g ranges between 0.76 and 0.8 and the mass extinction efficiency k ext varies between 0.5 and 1.1 m 2 g À1 ; these values are all in the range of those from independent direct measurements. Neglecting the partitioning between hematite and goethite and the assimilation of iron oxides by hematite, as it is often done with models, lowers the single-scattering albedo and increases the asymmetry factor in the UV-visible spectral region below 550 nm. The mass extinction efficiency is insensitive to the nature of the iron oxides but rather responds to variations in the number size distribution. The mineralogy of iron oxides should therefore be taken into account when assessing the effect of mineral dust on climate and atmospheric chemistry, in particular via interactions involving photolysis.

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Estimating the concentration of aluminum‐substituted hematite and goethite using diffuse reflectance spectrometry and rock magnetism: Feasibility and limitations

Jiang

Liu

et al. 2016

JGR Solid Earth

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Hematite and goethite in soils are often aluminum (Al) substituted, which can dramatically change their reflectance and magnetic properties and bias abundance estimates using diffuse reflectance spectroscopy (DRS) and magnetic techniques. In this study, synthetic Al‐substituted hematites and goethites and two Chinese loess/paleosol sequences were investigated to test the feasibility and limitations of estimating Al‐hematite and Al‐goethite concentration. When Al substitution is limited (Al/(Al + Fe) molar ratio < ~8%), the reflectance spectrum provides a reliable estimate of the goethite/hematite concentration ratio. New empirical relationships between the DRS band intensity ratio and the true concentration goethite/hematite ratio are estimated as goethite/hematite = 1.56 × (I425 nm/I535 nm) or goethite/hematite = 6.32 × (I480 nm/I535 nm), where I425 nm, I480 nm, and I535 nm are the amplitudes of DRS second‐derivative curves for characteristic bands at ~425 nm, ~480 nm, and ~535 nm, respectively. High Al substitution (> ~8%) reduces DRS band intensity, which leads to biased estimates of mineral concentration. Al substitution and grain size exert a control on coercivity distributions of hematite and goethite and, thus, affect the hard isothermal remanent magnetization. By integrating DRS and magnetic methods, we suggest a way to constrain hematite and goethite Al substitution in natural loess. Results indicate that hematite and goethite in Chinese loess have Al contents lower than ~8% and, thus, that DRS can be used to trace hematite and goethite concentration variations.

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Iron oxides in tropical soils on various parent materials

Cited by 20 publications

References 33 publications

Association of trace elements and dissolution rates of soil iron oxides

Association of trace elements and dissolution rates of soil iron oxides

Dominance of goethite over hematite in iron oxides of mineral dust from Western Africa: Quantitative partitioning by X‐ray absorption spectroscopy

Estimating the concentration of aluminum‐substituted hematite and goethite using diffuse reflectance spectrometry and rock magnetism: Feasibility and limitations

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