Toxicity of Cd2+ in mixture with Cu2+, Zn2+, Pb2+ and Fe2+ on growth and chlorophyll content of alga Scenedesmus quadricauda
1999
Fargasova, A. (Slovak University of Technology, Bratislava (Slovak Republic). Faculty of Chemical Technology)
This study has been based on the toxicity tests with alga Scenedesmus quadricauda under laboratory conditions. The investigation evaluated the toxicity of Cd2+ in mixture with Pb2+, Cu2+, Zn2+ and Fe2+ in the following concentrations (mg/L): Cd2+ and Cu2+ 0.01 and 0.1; Pb2+ and Zn2+ 0.1 and 1.0; Fe2+ 0.01. Toxicity of metals was evaluated singly and combined using various parameters (growth, total chlorophyll, chlorophyll a and chlorophyll b content). As individual metals, Cd2+ and Cu2+ had the strongest inhibitory effect on the algal growth. All the tested metals rapidly reduced chlorophyll contents. The strongest unfavourable effect on pigment production was observed after Fe2+ application when total chlorophyll, chlorophyll a and chlorophyll b contents were reduced by 64.7%, 52.5% and 70.6% respectively. All metals tested (Pb2+, Cu2+, Zn2+, Fe2+) reduced the inhibnitory effect of Cd2+ on the algal growth. However, when Pb2+ was applied in higher concentration (1.0 mg/L) its effect to Cd2+ was for algal growth either indifferent [Cd2+ (0.01) + Pb2+ (1.0)] or synergistic [Cd2+ (0.1) + Pb2+ (1.0)]. On the contrary, Cd2+ increased inhibitory effect of Pb2+ and Fe2+ and was mostly indifferent to Zn2+ and Cu2+. Pb2+, Cu2+, Zn2+ and Fe2+ generally increased Cd2+ unfavourable effect on chlorophyll contents in alga S. quadricauda. When the effect of metal-metal combinations on chlorophyll contents was examined the reciprocal synergistic effect was observed in majority of combinations with Pb2+, Zn2+ and Cu2+. In combinations with Fe either indifferent (chlorophyll a) or antagonistic effect was manifested. Antagonistic effect was observed also for combination Cd2+ (0.1) + Pb2+ (0.1) and chlorophyll b content in relation to both metals, and total chlorophyll in relation to Cd2+ alone. Reversible antagonistic effect was determined for combination Cd2+ (0.1) + Cu (0.1) and chlorophyll a content
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