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
More filters
Journal ArticleDOI
Si cycling in a forest biogeosystem – the importance of transient state biogenic Si pools
Michael Sommer,Hubert Jochheim,Axel Höhn,Jörn Breuer,Zbigniew Zagórski,J. Busse,Dietmar Barkusky,K. Meier,Daniel Puppe,Manfred Wanner,Danuta Kaczorek +10 more
TL;DR: In this article, the authors studied a forested site with absolute quartz dominance, and concluded that dissolution of a relictic, phytogenic Si pool seems to be the main process for the dissolved silica (DSI) observed.
Journal ArticleDOI
Magnesium retention on the soil exchange complex controlling Mg isotope variations in soils, soil solutions and vegetation in volcanic soils, Iceland
Sophie Opfergelt,Sophie Opfergelt,Kevin W. Burton,R. B. Georg,A.J. West,R. Guicharnaud,Bergur Sigfússon,Christopher Siebert,Sigurdur R. Gislason,Alex N. Halliday +9 more
TL;DR: In this paper, Mg isotope compositions are reported for parent basalt, bulk soils, clay fractions, exchangeable Mg, seasonal soil solutions, and vegetation for five types of volcanic soils in Iceland in order to improve the understanding of sources and processes controlling Mg supply to vegetation and export to the hydrosphere.
Journal ArticleDOI
Quantitative mapping of the soil rubification process on sand dunes using an airborne hyperspectral sensor
TL;DR: In this article, the authors used an airborne hyperspectral sensor to spatially map soil rubification on the surface of coastal sand dunes in Israel, which is defined as a pedogenesis stage in which iron is released from primary minerals to form free iron oxides that coat quartz particles in soils with a thin reddish film.
Journal ArticleDOI
Optical spectroscopic studies of the sorption of UO2+2 species on a reference smectite
TL;DR: The speciation of UO 2+2 (uranyl) on a reference smectite (SAz-1 from Cheto, Arizona, USA) has been investigated by electronic emission and Raman vibrational spectroscopies as mentioned in this paper.
Journal ArticleDOI
Potential use of Erica andevalensis and Erica australis in phytoremediation of sulphide mine environments: São Domingos, Portugal
TL;DR: The area around the Sao Domingos copper mine (Iberian Pyrite Belt) is subject of great environmental concern as acid mine water occurs several kilometres downstream of the mine and thousands of tons of mine waste are present as discussed by the authors.
References
More filters
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.