Acute and Chronic Toxicity of Aluminium Fluoride to Flora and Fauna in a Microcosm

During acute toxicity study of aluminium fluoride, Daphnia similis L. was found to be the most sensitive organism (EC₅₀ = 108.06 ppm) followed by Gambusia affinis Baird and Gerard (LC₅₀ = 354.0 ppm) and Lemna aequinoctialis L. (EC₅₀ for chlorophyll = 358.7ppm). The exposure (60 days) of producers and consumers at its sub-lethal concentration (35.4 ppm) casted toxic effects on them in artificial microcosms raised in the greenhouse. There was reduction in chlorophyll content (19-39%), dry weight (16%), acid phosphatase (ACP) (56%), alkaline phosphatase (ALP) (14%) and protein content (53%) of Ceratophyllum demersum L. The reduction in species richness (40%) and phytoplankton counts (counts = 47-54%) was significant during the study period while zooplankton counts (30%) in the first half of the study (day-30). Snail mortality was found nil while that of fish was moderate (37%). Their tissue biochemistry (ACP, ALP and protein content) was, however, altered significantly suggesting them to be under stress. AlF₃ also had cytotoxic effects in fish decreasing RBC counts (19%) and causing morphological abnormalities. From these findings, we conclude that there are significant toxic effects of aluminium fluoride to organisms in the food web of aquatic ecosystems.