Journal ArticleDOI
Iron Oxide Removal from Soils and Clays by a Dithionite-Citrate System Buffered with Sodium Bicarbonate
TLDR
In this article, the bicarbonate-buffered Na2S2O4-citrate system was used for removing free iron oxides from latosolic soils, and the least destructive of iron silicate clays.Abstract:
The oxidation potential of dithionite (Na2S2O4) increases from 0.37 V to 0.73 V with increase in pH from 6 to 9, because hydroxyl is consumed during oxidation of dithionite. At the same time the amount of iron oxide dissolved in 15 minutes falls off (from 100 percent to less than 1 percent extracted) with increase in pH from 6 to 12 owing to solubility product relationships of iron oxides. An optimum pH for maximum reaction kinetics occurs at approximately pH 7.3. A buffer is needed to hold the pH at the optimum level because 4 moles of OH are used up in reaction with each mole of Na2S2O4 oxidized. Tests show that NaHCO3 effectively serves as a buffer in this application. Crystalline hematite dissolved in amounts of several hundred milligrams in 2 min. Crystalline goethite dissolved more slowly, but dissolved during the two or three 15 min treatments normally given for iron oxide removal from soils and clays. A series of methods for the extraction of iron oxides from soils and clays was tested with soils high in free iron oxides and with nontronite and other iron-bearing clays. It was found that the bicarbonate-buffered Na2S2O4-citrate system was the most effective in removal of free iron oxides from latosolic soils, and the least destructive of iron silicate clays as indicated by least loss in cation exchange capacity after the iron oxide removal treatment. With soils the decrease was very little but with the very susceptible Woody district nontronite, the decrease was about 17 percent as contrasted to 35–80 percent with other methods.read more
Citations
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Journal ArticleDOI
Mineralogy and genesis of selected soils and their implications for forest management in central and northeastern British Columbia
Joselito M. Arocena,Paul Sanborn +1 more
TL;DR: In this paper, the authors examined pedogenesis on various parent materials to support studies of long-term forest productivity, and sampled nine pedons developed on till (Bobtail, Lucille Mountain, Skulow Lake, Log Lake, Topley, and Kiskatinaw), including mica, kaolinite, chlorite, smectite, and vermiculite.
Journal ArticleDOI
Chemistry and microbiology of the Critical Zone along a steep climate and vegetation gradient in the Chilean Coastal Cordillera.
Ralf A. Oeser,Nicole Stroncik,Lisa-Marie Moskwa,Nadine Bernhard,Mirjam Schaller,Rafaella Canessa,Liesbeth van den Brink,Moritz Köster,Emanuel Brucker,Svenja Stock,Juan Pablo Fuentes,Roberto Godoy,Francisco Matus,Rómulo Oses Pedraza,Rómulo Oses Pedraza,Pablo Osses Mc-Intyre,Leandro Paulino,Oscar Seguel,Maaike Y. Bader,Jens Boy,Michaela A. Dippold,Todd A. Ehlers,Peter Kühn,Yakov Kuzyakov,Peter Leinweber,Thomas Scholten,Sandra Spielvogel,Marie Spohn,Kirstin Übernickel,Katja Tielbörger,Dirk Wagner,Friedhelm von Blanckenburg +31 more
TL;DR: In this paper, the authors explored the Critical Zone, the Earth's uppermost layer, in four key sites located in desert, semi-arid, Mediterranean, and temperate climate zones of the Chilean Coastal Cordillera, with the focus on weathering of granitic rock.
Journal ArticleDOI
Advances in characterization of soil clay mineralogy using X‐ray diffraction: from decomposition to profile fitting
TL;DR: In this paper, the authors used X-ray diffraction (XRD) patterns to characterize the mineralogy and crystal chemistry of the <2 μm fraction along a profile typical of soils from Western Europe and North America (Neo Luvisol).
Journal ArticleDOI
Superfícies geomórficas e atributos de Latossolos em uma seqüência Arenítico-Basáltica da região de Jaboticabal (SP)
TL;DR: In this paper, soil and geomorphic surfaces were studied on a sandstone/basalt hillslope segment, commonly found in the Jaboticabal region (NW Sao Paulo State).
Journal ArticleDOI
Cation-ratio and accelerator radiocarbon dating of rock varnish on mojave artifacts and landforms.
Ronald I. Dorn,Douglas B. Bamforth,Thomas A. Cahill,John C. Dohrenwend,Brent D. Turrin,Douglas J. Donahue,A. J. T. Jull,Austin Long,Michael E. Macko,Edward B. Weil,David S. Whitley,T. H. Zabel +11 more
TL;DR: The first accelerator radiocarbon dates of rock varnish K+ + Ca2+/Ti4+ ratios with age in the Mojave Desert, eastern California are reported along with potassium/argon ages of lava flows and conventional radiocese ages of pluvial lake shorelines.
References
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Book
Soil Chemical Analysis
TL;DR: Soil chemical analysis, Soil Chemical Analysis (SCA), this paper, is a technique for soil chemical analysis that is used in the field of Soil Chemistry and Chemical Engineering.
Journal ArticleDOI
Iron Oxide Removal from Soils and Clays1
N. H. Aguilera,M. L. Jackson +1 more
TL;DR: In this article, a procedure is presented which employs sodium dithionite (Na2S2O4, hyposulfite, or "hydrosulfite") as the reductor, and 0.3 molar citrate with or without Fe-3 specific Versene as the chelating reagent.