| heal.abstract |
Three medicinal species, spearmint (Mentha spicata L.), lemon verbena (Lippia citriodora L.) and peppermint (Mentha piperita L.), were grown in pots to study the effect of trivalent (Cr (III) and hexavalent (Cr (VI) Chromium (Cr) on the total Cr concentration in the vegetative plant parts. A completely randomized block design with five concentrations (0, 1, 5, 10, 15 mg kg-1) of Cr (III) and Cr (VI) was laid out. Trivalent Cr was applied as CrCl36H2O and hexavalent Cr as K2Cr2O7. Total Cr concentration in the plant tissues was measured by two methods: dry ash method (DAM) and microwave-assisted acid digestion method (MADM). Increasing Cr additions to the soil resulted in an increase in the total Cr concentration in the vegetative parts of all the plants measured by both methods and irrespective of the Cr oxidation state (i.e. from 0.72 to 2.55 mg kg-1, from 0.78 to 10.12 mg kg-1, and from 0.43 to 7.41 mg kg-1, in lemon verbena, spearmint and peppermint, respectively, for Cr added as Cr (III) and from 0.82 to 6.02 mg kg-1, from 1.07 to 6.02 mg kg-1 and from 1.99 to 11.16 mg kg-1, in lemon verbena, spearmint and peppermint, respectively, for Cr added as Cr (VI)). Uptake of Cr was relatively low in all plants, but the total Cr concentration was significantly lower in plants exposed to Cr (III) than Cr (VI) in both methods of measurement. The total Cr concentration measured by the MADM was significantly higher than the total Cr measured by the DAM. |
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