Evaluación de la toxicidad de mezclas binarias de cobre, cinc y arsénico sobre Daphnia obtusa (Kurz, 1874) (Cladocera, Crustacea)

Abstract

Evaluation of the toxicity of binary mixtures of copper, zinc, and arsenic on Daphnia obtusa (Kurz, 1874) (Cladocera, Crustacea)The protection of aquatic ecosystems is based on environmental norms that consider the maximum concentration allowed for individual chemical substances. Nevertheless, in reality there are complex mixtures in which multiple interactions among the constituents occur (i.e. additive, synergic and antagonistic). Among the chemical agents that are present in high concentrations in the aquatic ecosystems affected by mining activity are copper, zinc, and arsenic. The aim of this investigation was to determine what type of interactions occur between these elements and therefore, cute toxicity tests between binary mixtures of Zn:As, Zn:Cu and Cu:As on Daphnia obtusa were performed. The type of interaction was determined through the concentration-addition and synergistic ratio models. The results show that zinc exerts an antagonistic interaction on arsenic, while arsenic has a synergistic effect on zinc. As for the interaction Zn: Cu, when the concentration of zinc in the mixture was increased, an antagonistic effect on copper was observed. In general, the different binary mixtures turned out to be antagonistic. The concentration-addition model appears to be a good tool to predict the toxicity of metal mixtures.