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The oxidation of Cr(III) to Cr(VI) in the environment by atmospheric oxygen during the bush fires by N. Panichev; W. Mabasa; P. Ngobeni; K. Mandiwana; S. Panicheva is a Environmental Science article available to read on EtoBox.

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The presence of Cr(VI) in soils and plants of remote unpolluted areas can be explained by partial oxidation of Cr(III) with atmospheric oxygen during seasonable bush fires, which are rather frequent event in South Africa. Experiments with thermal treatment of a veld grass, Hyperthelia dissoluta, in muffle furnace at high temperature, followed by electrothermal atomic absorption spectrometry (ETAAS) determination of chromium, show a remarkable increase in Cr(VI) concentration from initial 2.5 to 23.2% after the treatment of grass ash at 500 • C and to 58.1% at 900 • C. Before ETAAS determination, the two chromium species of interest were separated by the treatment of samples with 0.1 M Na 2 CO 3 . Thermodynamic calculations confirm the possibility of Cr(III) to Cr(VI) oxidation with atmospheric oxygen at high temperature in alkaline media, which is typical for vegetation ash. Analysis of field samples show that percent of Cr(VI), in respect to the total amount of chromium increased from initial 2.5% in grass to 9.3% in ash of grass. Without oxidation the percent of Cr(VI) in grass and ash of grass should be a constant value. After the fire Cr(VI) concentration in top soil (0-3 cm) i

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Author

N. Panichev; W. Mabasa; P. Ngobeni; K. Mandiwana; S. Panicheva

Publisher

Elsevier Science; Elsevier ; Elsevier BV (ISSN 0304-3894)

Published

2008

Language

EN

Field

Environmental Science (Physical Sciences)