Correlation between acute toxicity for Daphnia magna, Aliivibrio fischeri and physicochemical variables of the leachate produced in landfill simulator reactors.

Due to the diversified nature of municipal solid waste and the different stages of its decomposition, the formed leachates result in a complex chemical mixture with toxic potential. These chemicals can cause environmental problems, such as the contamination of surface or groundwater, thus affecting the balance of aquatic ecosystems. The aim of our study was to evaluate the acute toxicity of leachates in Daphnia magna and Aliivibrio fischeri and to identify the main physicochemical variables that influence the toxicity of the landfill leachates produced in reactors within pilot simulations. Acute toxicity tests carried out on D. magna and A. fischeri showed that the leachates produced inside the reactors are highly toxic, presenting EC50(48h) < 1% for D. magna and EC50(15min) < 12% for A. fischeri. This result indicates that microcrustaceans are more sensitive to leachates, making them more suitable to our study. Pb showed the highest correlation with EC50(48h), suggesting that Pb is the main chemical variable indicative of toxicity for the conditions of the experiment. In smaller scale, phosphate (PO43-) and nitrate (NO3-) were the macronutrients that most influenced the toxicity. Clearly, this correlation should be viewed with caution because the synergistic effects of this complex mixture are difficult to observe.