Browsing by Author "Munagamage, T."

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    Comparison of Sensitivity of Tropical Freshwater Microalgae to Environmentally Relevant Concentrations of Cadmium and Hexavalent Chromium in Three Types of Growth Media
    (Bull Environ Contam Toxicol, 2020) Munagamage, T.; Rathnayake, I.V.N.; Pathiratne, A.
    Sensitivity of tropical freshwater microalgae (Mesotaenium sp., Chlorococcum sp. and Scenedesmus sp.) to environmentally relevant concentrations of hexavalent chromium (Cr6+) and cadmium (Cd2+) was compared individually in three growth media viz. Bold’s Basal Medium (BBM), Test Medium 1 (TM1) and Test Medium 2 (TM2) based on fluorescence reduction. Free metal content of growth media was determined by Visual MINTEQ (version 3.1). After 24 h, relative fluorescence of microalgae in the three media decreased with increased metal concentration showing a concentration dependent graded toxicity response. All microalgae were more sensitive to the metals when grown in TM1, when compared, more sensitive to Cr6+ than Cd2+. Metal speciation indicated that TM1 and TM2 media have higher percentage of bioavailable Cd2+ than BBM, and chromium was present mainly as CrO42− and HCrO4−. The results suggest that the TM1 medium is more suitable under short term exposure of microalgae to metals in environmental monitoring.
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    Sensitivity of Four Cyanobacterial Isolates from Tropical Freshwaters to Environmentally Realistic Concentrations of Cr6+
    (Springer US., 2016) Munagamage, T.; Rathnayake, I.V.N.; Pathiratne, A.; Megharaj, M.
    Sensitivity of four tropical cyanobacteria viz. Coelosphaerium sp., Synechococcus sp., Oscillatoria sp. and Chroococcus sp. to environmentally relevant concentrations of Cr6+, Cd2+ and Zn2+was assessed based on fluorescence change as a proxy for growth reduction. At 24 h exposure, the growth reduction inthe cyanobacteria followed the order: Zn2+ < Cr6+ ≤ Cd2+. Of the four cyanobacteria, Synechococcus was the most sensitive for Cr6+, where as Chroococcus was the most sensitive for Cd2+and Zn2+. Sensitivity was gradually decreased by 96 h implying the acquisition of tolerance by cyanobacteria to heavy metal ions with prolonged exposure.