Selenium is an essential trace element for many organisms, including humans, but it
is bioaccumulative and toxic at higher than homeostatic levels. Both selenium deficiency
and toxicity are problems around the world. Mines, coal-fired power plants, oil refineries,
and agriculture are important examples of anthropogenic sources, generating contaminated
waters, and wastewaters. For reasons of human health and ecotoxicity, selenium concentration
has to be controlled in drinking-water and in wastewater, as it is a potential pollutant
of water bodies. In this regard, in the present study, the ability of sunflower (Helianthus
annuus L.) to tolerate and accumulate selenium was assessed in hydroponic culture
as a model ofrhizofiltration system. Selenium content and the chlorophyll parameters
of sunflower plant treated using different concentrations of selenium in two forms
of sodium selenite and sodium selenate were measured to clarify (1) there sponse of
sunflower to selenium tolerance capacity and (2) the relationship between selenium,
chlorophyll fluorescence parameters, and photosynthetic pigments contents. The results
showed that selenium content in sunflower plants significantly increased by increasing
added selenium levels. Furthermore, Chl a and b were not impaired after 3 weeks from
selenium exposure up to3 mg L1 for both selenite and selenate. Moreover, sunflower
plants have a high selenium tolerance capacity for hydroponic clean-up. Translocation
of selenate from sunflower roots to shoots was easier comparing with selenite in concept
of phytoremediation processes.
