Heavy Metal Accumulation by the Halophyte Species Mediterranean Saltbush (original) (raw)

2004, Journal of Environmental Quality

1. and their use for phytoextraction purposes has been recommended To identify Cd-and Zn-accumulating plants exhibiting a high 2003). Most hyperaccumulators, however, are difficult growth rate, seeds from the halophyte species Mediterranean saltbush to manage and have a shallow root system, and their (Atriplex halimus L.) were collected on a heavy-metal-contaminated interest is therefore limited in the case of deep contamisite in southeastern Spain (Llano del Beal, Cartagena). Seedlings from this ecotype were exposed for 3 wk to 0.1 mM Cd or Zn in a nutrient nation (Keller et al., 2003). solution in a fully controlled environment. All plants remained alive The use of deep-rooting halophyte species is of particand no significant growth inhibition was recorded until the end of ular interest in this context because these plants are the experiment. Mean Cd and Zn accumulation in aerial parts was naturally present in environments characterized by an 830 and 440 mg kg Ϫ1 , respectively, and the rate of metal translocation excess of toxic ions, mainly sodium and chloride. Several even increased with the duration of stress exposure. Resistance to studies demonstrated that some tolerance mechanisms heavy metals in this species may be partly linked to precipitation of Cd operating at the whole-plant level are not always specific in oxalate crystals in the stems. A Cd-induced decrease in glutathione to sodium and that other toxic elements such as copper, concentration also suggests that phytochelatins overproduction may zinc, or cadmium may accumulate in salt glands or trioccur in these conditions. We conclude that Mediterranean saltbush, chomes in tamaris [Tamarix aphylla (L.) Karst.], marshwhich is able to produce up to 5 Mg dry matter ha Ϫ1 yr Ϫ1 , may be an effective species for phytoextraction and should be tested for this daisy [Armeria maritima (Mill.) Willd.], and gray manpurpose in field conditions. grove [Avicennia marina (Forsk.) Vierh.] (Hagemeyer and Waisel, 1988; Neumann et al., 1995;). Among the halophyte flora, species * Significantly different from the values of the corresponding control at the 0.05 probability level according to the Scheffé F test. other C4 species, which need Na for efficient phospho-** Significantly different from the values of the corresponding control at enolpyruvate regeneration. the 0.01 probability level according to the Scheffé F test. † Each value is the mean of three replicates Ϯ standard errors.