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
A comparison of several methods for the determination of iron hydroxides and associated orthophosphates in estuarine particulate matter
Marc Lucotte,Bruno d'Anglejan +1 more
TL;DR: In this article, five different methods commonly used for the extraction and determination of iron hydroxides and/or the associated phosphorus held in marine seston or in sediments have been tested on single-phase minerals (goethite and apatite), on reference minerals (SO1 and SO2), and on suspended-matter samples from the St. Lawrence Estuary and from the estuary of the Eastmain River, a major James Bay affluent in northern Quebec, Canada.
Journal ArticleDOI
Role of soil constituents in fixation of soluble Zn, Cu, Ni and Cd added to soils
TL;DR: In this paper, the role of Fe oxides and carbonates on fixation of Cu, Cd, Zn and Ni was assessed in 28 soils from 2 toposequences (Vietnam, Spain) and 13 European topsoils with different soil characteristics.
Journal ArticleDOI
Potassium fertilizer and other materials as countermeasures to reduce radiocesium levels in rice: Results of urgent experiments in 2011 responding to the Fukushima Daiichi Nuclear Power Plant accident
Naoto Kato,Nobuharu Kihou,Shigeto Fujimura,Masaharu Ikeba,Naruo Miyazaki,Yukio Saito,Tetsuya Eguchi,Sumio Itoh +7 more
TL;DR: In this article, the use of K fertilization was shown to be an effective and practical countermeasure to reduce radiocesium uptake by rice from several soil types in Japanese paddy rice culture.
Journal ArticleDOI
Isotopic fractionation of dissolved organic carbon in shallow forest soils as affected by sorption
TL;DR: In this article, the potential effects of sorption on the δ 13 C of dissolved organic carbon in field and laboratory experiments were investigated, and it was shown that selective sorption of organic C fractions changes δ13 C in a way that mimics metabolic transformation and decomposition.
Journal ArticleDOI
Intensification of monsoon, microclimate and asynchronous C4 appearance: Isotopic evidence from the Indian Siwalik sediments
Prasanta Sanyal,Anindya Sarkar,S. K. Bhattacharya,Rohtash Kumar,Sumit K. Ghosh,Shailesh Agrawal +5 more
TL;DR: In this paper, the D/H ratio of pedogenic clay and the 18 O/16 O ratio of carbonate nodules collected from Siwalik sediments in India indicates three episodes of monsoon intensification at ~11 Ma, 6 Ma and 3 Ma.
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.