Avaliação e Identificação da toxicidade (Fase I) dos sedimentos do estuário do Rio Capibaribe utilizando embriões de Danio rerio

Abstract

The estuarine complex of the Capibaribe River is one of the most important water systems in the state of Pernambuco. Unfortunately, the activity of human activities in its surroundings associated to the high loads of contaminants originating mainly from the discharge of domestic and industrial effluents, have resulted in a high level of environmental pollution. Previous studies have pointed out several groups of substances responsible for their contamination. In this work, the Toxicity Assessment and Identification (AIT) process was employed using Danio rerio embryos as test organism exposed to the elutriates of the estuarine sediments, aiming at a new alternative toxicity, the use of a marine vertebrate and sublethal parameters (heart rate and teratogenicity). The principle of this method is based on the fractionation of the samples by means of a series of processes (filtration, aeration, additions of EDTA and Sodium thiosulphate), aiming to make certain groups of substances unavailable to verify their effects. By means of the results obtained the sublethal parameters, demonstrated greater sensitivity to the samples and confirmed that they are relevant endopoints to be included in ecotoxicological tests. Before carrying out the AIT manipulations, it was observed in the Base Test that the toxicity of the samples is influenced by rainfall, demonstrating the importance of the evaluation in the dry and rainy periods in environmental samples. After confirming the toxicity of the three collection points by the Base Test and the application of TIA manipulations, a significant reduction in the toxicity of elutriates was verified, especially those manipulated with EDTA filtration and addition. These manipulations of AIT indicated, respectively, compounds associated with sediment particles and cationic metals as being more responsible for sediment toxicity. This variety of toxic agents can be attributed to the diversity of activities carried out in the area, the different influences suffered by the points studied and the regime of rains, tides and currents, indicating the need for constant monitoring of the region.