Phytoaccumulation of Trace Elements by Wetland Plants: I. Duckweed
- Adel Zayed,
- Suvarnalatha Gowthaman and
- Norman Terry *
Dep. of Plant Production, College of Agric. at Saba Basha, Univ. of Alexandria, Bolkly 21531, Alexandria, Egypt; Dep. of Plant Cell Biotechnology, Central Food Technological Research Inst., Mysore 570013, India; 111 Koshland Hall, Dep. of Plant and Microbial Biology, Univ. of California, Berkeley CA 94720-3102. Abstract
There has been much interest recently in the use of constructed wetlands for the removal of toxic trace elements from wastewaters. Wetland plants play an important role in the trace elements removal process. It is not known, however, which wetland plant species absorb specific trace elements at the fastest rates. Such knowledge is essential to maximize the efficiency of trace element removal by wetlands. In this study, we investigated the potential of duckweed (Lemna minor L.) to accumulate Cd, Cr, Cu, Ni, Pb, and Se when supplied individually in a nutrient solution at a series of concentrations ranged from 0.1 to 10 mg L−1. The results show that under experimental conditions, duckweed proved to be a good accumulator of Cd, Se, and Cu, a moderate accumulator of Cr, and a poor accumulator of Ni and Pb. The highest concentrations of each trace element accumulated in duckweed tissues were 13.3 g Cd kg−1, 4.27 g Se kg−1, 3.36 g Cu kg−1, 2.87 g Cr kg−1, 1.79 g Ni kg−1, and 0.63 g Pb kg−1. Duckweed exhibited some symptoms of toxicity (e.g., reduced growth, chlorosis) at higher levels of element supply (except for Cr). The toxicity effect of each trace element on plant growth was, in descending order of damage, Cu > Se > Pb > Cd > Ni > Cr. We conclude that duckweed shows promise for the removal of Cd, Se, and Cu from contaminated wastewater since it accumulates high concentrations of these elements. Further, the growth rates and harvest potential make duckweed a good species for phytoremediation activities.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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