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Title: Analysis of Arsenic Uptake by Plant Species Selected for Growth in Northwest Ohio by ICP-OES

Author
item ROFKAR, J - UNIVERSITY OF TOLEDO
item DWYER, D - UNIVERSITY OF TOLEDO
item Frantz, Jonathan

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2007
Publication Date: 12/15/2007
Citation: Rofkar, J., Dwyer, D., Frantz, J. 2007. Analysis of Arsenic Uptake by Plant Species Selected for Growth in Northwest Ohio by ICP-OES. Communications in Soil Science and Plant Analysis. 38: 2505-2517.

Interpretive Summary: Cleaning pollution from soils and water using plants, or phytoremediation, is a low maintenance, environmentally friendly alternative to more traditional clean-up techniques. Arsenic is a potential pollutant that could be cleaned up with phytoremediation. Hyperaccumulation of arsenic by plants is considered the most useful approach in phytoremediation, but the known hyperaccumulators are subtropical in origin with a potentially limited range of growth environments. To find additional species that may be useful in phytoremediation of arsenic, we assayed 22 plant species applicable to the environmental conditions prevalent in northwest Ohio. Species adapted to moist soils were grown from seedlings and grown without soil containing 0, 10, or 50 mg As L-1. Species adapted to dry or moderately moist soils were grown from seeds in potting mix and irrigated with water containing 0, 10, 25, 100, or 250 mg As L-1. After one and two weeks, respectively, stems and leaves were harvested, dried, and acid-digested. In addition, solutions (25 mL) containing 0, 10, 25, 100, or 250 mg As L-1 were added to potting mix (1 g); the mixtures were agitated for 24 h, filtered, and centrifuged. The samples were analyzed for arsenic using elemental analysis. Approximately 99% of arsenic added to the potting mix remained in solution, suggesting that the arsenic to which the plants were exposed was bioavailable. The accumulation of arsenic was greatest in plants grown in potting mix and irrigated with 250 mg As L-1 and included Rudbeckia hirta (660.6 mg As kg-1 dw), Lupinus perennis (333.3 mg As kg-1 dw), Echinacea purpurea (297.5 mg As kg-1 dw), Coreopsis lanceolata (258.1 mg As kg-1 dw), Lepidium virginicum (214.3 mg As kg-1 dw), and Linum lewisii (213.8 mg As kg-1 dw). The accumulation of arsenic in plants grown hydroponically was greatest in Helenium autumnale (127.8 mg As kg-1 dw) and Aster novae-angliae (132.2 mg As kg-1 dw). New tissues of H. autumnale contained four times as much arsenic (362.6 mg As kg-1 dw) than old tissues (88.7 mg As kg-1 dw) from the same plants, suggesting that newly developed tissues should be assayed separately to obtain true estimates of accumulation. This work begins to identify plant species that are already adapted to this region of the world and could be used for cleaning up arsenic-contaminated sites.

Technical Abstract: Phytoremediation of arsenic-contaminated soils and water is a low maintenance, environmentally friendly alternative to more traditional remediation techniques. Hyperaccumulation of arsenic by plants (e.g. Pteris spp. and Pityrogramma calomelanos) is considered the most useful approach in phytoremediation. However, the known hyperaccumulators are subtropical in origin with a potentially limited range of applicable environments. To expand the number of useful species, we assayed 22 plant species applicable to the environmental conditions prevalent in northwest Ohio. Species adapted to moist soils were grown from seedlings and assayed hydroponically in nutrient solution containing 0, 10, or 50 mg As L-1. Species adapted to dry or moderately moist soils were grown from seeds in potting mix; young plants (1 g fresh biomass), thereafter, were irrigated with water containing 0, 10, 25, 100, or 250 mg As L-1. After one and two weeks, respectively, stems and leaves were harvested, dried, and acid-digested. In addition, solutions (25 mL) containing 0, 10, 25, 100, or 250 mg As L-1 were added to potting mix (1 g); the mixtures were agitated for 24 h, filtered, and centrifuged. The resultant supernatant and the plant digests were analyzed for arsenic using inductively coupled plasma - optical emission spectrometry (ICP-OES). Approximately 99% of arsenic added to the potting mix remained in solution, suggesting that the arsenic to which the plants were exposed was bioavailable. The accumulation of arsenic was greatest in plants grown in potting mix and irrigated with 250 mg As L-1: Rudbeckia hirta (660.6 mg As kg-1 dw), Lupinus perennis (333.3 mg As kg-1 dw), Echinacea purpurea (297.5 mg As kg-1 dw), Coreopsis lanceolata (258.1 mg As kg-1 dw), Lepidium virginicum (214.3 mg As kg-1 dw), and Linum lewisii (213.8 mg As kg-1 dw). The accumulation of arsenic in plants grown hydroponically was greatest in Helenium autumnale (127.8 mg As kg-1 dw) and Aster novae-angliae (132.2 mg As kg-1 dw). New tissues of H. autumnale contained four-fold greater concentrations of arsenic (362.6 mg As kg-1 dw) than old tissues (88.7 mg As kg-1 dw) from the same plants, suggesting that newly developed tissues should be assayed separately to obtain true estimates of accumulation. Plant species that accumulated the greatest concentrations of arsenic are to be tested further in the field to determine the effect of seasonal and other environmental parameters on arsenic accumulation.