Modulation of antioxidant defense system after long term arsenic exposure in Zantedeschia aethiopica and Anemopsis californica.

Zantedeschia aethiopica (calla lily) and Anemopsis californica (yerba mansa) are plant species capable of accumulating arsenic (As) and therefore proposed as phytoremediation for removal of As from drinking water. The effects of a continuous 6 month As exposure (34±11 µg/L) from local contaminated groundwater on the antioxidant response of Z. aethiopica and A. californica were evaluated in leaves and stems of the plants bimonthly in a subsurface flow constructed wetland. As increased the activities of the antioxidant enzymes ascorbate peroxidase, glutathione reductase and catalase where higher levels were observed in Z. aethiopica than A. californica. No significant differences were detected on lipid peroxidation levels or antioxidant capacity evaluated by ORAC and DPPH assays or total phenol contents in any part of the plant, although in general the leaves of both plants showed the best antioxidant defense against the metal. In conclusion, Z. aethiopica and A. californica were able to cope to As through induction of a more sensitive enzymatic antioxidant response mechanism.

Growth response and tissue accumulation trends of herbaceous wetland plant species exposed to elevated aqueous mercury levels.

The impacts of elevated aqueous mercury levels (0, 2, and 4 ppm) on the growth status and mercury tissue concentrations of Eleocharis parvula, Saururus cernuus, Juncus effuses, Typha latifolia, and Panicum hemitomon were determined. Both short-term (net CO2 assimilation) and long-term (biomass) indicators of plant growth status suggest that Eleocharis parvula, Saururus cernuus, and Juncus effuses were relatively unimpacted by elevated mercury levels, whereas Typha latifolia and Panicum hemitomon were somewhat impacted at elevated mercury levels. Eleocharis parvula, Panicum hemitomon, and Typha latifolia generally had the greatest overall belowground tissue concentrations of mercury (2 ppm treatment: 7.21, 7.32, and 9.64 ppm respectively; 4 ppm treatment: 16.23, 18.23, and 13.98 ppm, respectively) and aboveground tissue concentrations of mercury (2 ppm treatment: 0.01, 0.04, 0.02; 4 ppm treatment: 0.26; 0.11; 0.17 ppm, respectively). However, the species investigated in this study demonstrated lower levels of mercury accumulation into tissues when compared with similar investigations of other aquatic plants, suggesting that the above species are not optimal for phytoremediation efforts.