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Cd Tolerance and Accumulation in the Aquatic Macrophyte, Chara australis: Potential Use for Charophytes in Phytoremediation

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posted on 2011-06-15, 00:00 authored by Bernadette L. Clabeaux, Divina A. G. Navarro, Diana S. Aga, Mary A. Bisson
We investigated the potential use of the alga Chara australis (R. Br.) forphytore mediation of Cd-contaminated sediments in aquatic systems. Chara tolerated up to 20 mg added Cd (kg soil)−1 in laboratory culture. Chlorophyll a and b levels were not affected even at Cd concentrations that suppressed growth. Levels of glutathione were suppressed at 2–35 mg added Cd (kg soil)−1 to 200–350 nmol GSH (g DW)−1, while control levels were 660 nmol GSH (g DW)−1). Histochemical studies showed Cd occurred throughout cell walls and cytoplasm in plants grown in 5–20 mg Cd (kg soil)−1. Quantification using ICP-MS showed the maximum concentration in shoots was 72 mg Cd (kg DW)−1 at 35 mg added Cd (kg soil)−1, while the maximum in rhizoids was 116 mg Cd (kg DW)−1 at 25 mg added Cd (kg soil)−1. The bioconcentration factor (BCF, concentration in plant/concentration in soil) exceeded 1.0, the critical value for hyperaccumulators, for shoots exposed to 35 mg Cd (kg soil)−1 and rhizoids exposed to ≥25 mg Cd (kg soil)−1. Translocation factors (TF, shoot concentration/rhizoid concentration) did not exceed 1.0 for any treatment. While Chara cannot be considered a hyperaccumulator, it shows promise for use in phytoremediation efforts.

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