Determining manganese oxidation state in soils using X-ray absorption near-edge structure (XANES) spectroscopy

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Soil Science Society of America Journal

DOI:https://doi.org/10.2136/sssaj1995.03615995005900060005x· OSTI ID:200376

Schulze, D G ^[1]; Sutton, S R ^[2]; Bajt, S ^[3]

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1. Purdue Univ., West Lafayette, IN (United States)
2. Univ. of Chicago, IL (United States)
3. Brookhaven National Lab., Upton, NY (United States)

The redox chemistry of soil Mn is important in Mn uptake by plants, the movement of trace elements absorbed on or occluded in Mn-oxides, and the etiology of some soil-borne plant fungal diseases. The objectives of this study were to develop calibration curves for determining Mn oxidation states in moist soil samples using micro-x-ray absorption near-edge structure spectroscopy and to test the method on selected soils. Oxidation-state standards were prepared by mixing dry powders and a synthetic Na-birnessite, to obtain various Mn{sup 2+} mole fractions f(Mn{sup 2+}). Corundum ({alpha}-Al{sub 2}O{sub 3}) was used as a diluent to prepare mixtures containing 50, 1000, and 100000 mg Mn/kg. Quantitative analysis of Mn oxidation state is possible using either the energy of the pre-edge peak at 6540 eV or a ratio based on the intensity of the Mn{sup 2+} white line peak at 6552.6 eV divided by the intensity of the Mn{sup 2+} white line peak at 6560.9 eV. The white line intensity ratio is more sensitive, with an estimated lower detection limit of 20 mg Mn/kg using a 300 by 300 {mu}m spot, and predicts f(Mn{sup 2+}) with an accuracy of {+-}0.1 mole fraction (95% confidence interval) through most of its range. The f(Mn{sup 2+}) for four air-dried Indiana surface soils ranged from 0.26 to 0.44 {+-}0.1. Saturation and reduction for 5 d resulted in complete reduction of Mn in the soil matrix. 39 refs., 9 figs., 1 tab.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY
• Sponsoring Organization: USDOE
• DOE Contract Number: FG02-92ER14244; AC02-76CH00016
• OSTI ID: 200376
• Journal Information: Soil Science Society of America Journal, Journal Name: Soil Science Society of America Journal Journal Issue: 6 Vol. 59; ISSN 0361-5995; ISSN SSSJD4
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
54 ENVIRONMENTAL SCIENCES
55 BIOLOGY AND MEDICINE
BASIC STUDIES
ABSORPTION SPECTRA
MANGANESE OXIDES
OXIDATION
REDOX REACTIONS
REDUCTION
ROOT ABSORPTION
SOIL CHEMISTRY
SOILS
UPTAKE
X-RAY SPECTRA