PHYSIOLOGICAL RESPONSE OF SCENEDESMUS QUADRICAUDA (TURPIN) DE BRÉBISSON TO LEAD (Pb), NITRATE (NO3) AND PHOSPHATE (PO4)
PHYSIOLOGICAL RESPONSE OF SCENEDESMUS QUADRICAUDA (TURPIN) DE BRÉBISSON TO LEAD (Pb), NITRATE (NO3) AND PHOSPHATE (PO4)
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Date
2014-08
Authors
KALU, PROMISE CHIMDIRIM
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Abstract
A study on the physiological response of Scenedesmus quadricauda to Lead(Pb), Nitrate and Phosphate was conducted by examining their interactive effects on the growth, chlorophyll a, dry weight, phenotypic plasticity, cell counts and antioxidant enzyme activities during a 18-day period. The results showed that at lower nitrate (1.8 ×10-5 and 1.8×10-6) and phosphates (1.2 ×10-6 and 1.8×10-7) concentrations, there was a decrease in the biomass production compared to the control (1.8×10-4). The exposure to Pb caused a significant reduction in biomass production of the microalga. The reduction in biomass production had a linear positive relationship with increasing Pb concentration. An increase in the activities of Superoxide dismutase, Peroxidase, Catalase and Glutathione-S-transferase was observed when the microalga was grown under limited nitrate and phosphate concentrations. The activities of the enzymes were further increased when nutrient limitation was combined with Pb stress. These results show that the severity of Pb pollution in aquatic ecosystems will vary depending on the concentrations of important structural nutrients like N and P. This means that even very low Pb concentrations can exert significant toxicity to microalgae when the concentrations of major nutrients are limiting in water.
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A THESIS SUBMITTED TO THE SCHOOL OF POST-GRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE DEGREE IN BIOLOGICAL SCIENCES DEPARTMENT OF BIOLOGICAL SCIENCES, FACULTY OF SCIENCES AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA.
Keywords
PHYSIOLOGICAL RESPONSE,, SCENEDESMUS,, QUADRICAUDA,, (TURPIN),, DE BRÉBISSON,, LEAD (Pb),, NITRATE (NO3),, PHOSPHATE (PO4)