Resumo

MIRANDA, M.G.  e  QUIROZ, A.. Effect of photoperiod to absorb lead by Lemna gibba L. (Lemnaceae). Polibotánica [online]. 2013, n.36, pp.147-161. ISSN 1405-2768.

Lead comes to municipal wastewater from industries battery, welding, painting, etc. causing damage to living beings, so it is necessary to promote the development of technologies that help to improve the quality of the effluent and at the same time be appropriate to the socioeconomic context of the country. This paper proposes the use of an aquatic angiosperm with exponential growth and easy handling in laboratory culture (Lemna gibba) family Lemnaceae to absorb lead (PbNO₃)₂ using five concentrations at the level of bioassay in the laboratory, under the effect of two different photoperiod conditions (continuous light and 12 h light/12 h dark) for four days because since this day from the Pb release to the environment. The results indicate that, in the two lowest concentrations of Pb (30 and 50 ppm), photoperiod 12/12 is more favorable for absorption (9405 μgl^-1 más y 18,895 μgl^-1 more respectively), whereas the other three (100, 200 and 300 ppm) it was the condition of continuous light. (6 600.66 μgl^-1, 1949 μgl^-1, 5587 μgl^-1 more respectively). The knowledge derived from this study to optimize the use of Lemna gibba in tertiary treatment of wastewater.

Palavras-chave : Lemna gibba; photoperiod; lead; water treatment.