Pantanal Sul-Mato-Grossense: avaliação da qualidade da água por meio da quantificação de contaminantes emergentes e ensaio de embriotoxicidade

Abstract

The indiscriminate increase in agro-industrial activities and urbanization has resulted in the loss of biodiversity in the Pantanal and adjacent rivers. Consequently, this has contributed to the release of emerging contaminants (ECs) into aquatic matrices. The Aquidauana (RA) and Miranda (RM) rivers, located in the Pantanal plain, are of economic and ecological importance to the region. The embryotoxicity test in Zebrafish (Danio rerio) is a complementary assessment of environmental quality, providing physiological responses regarding the toxic and teratogenic potential of environmental samples. The objective of the study was to assess the water quality of the RA and RM through environmental monitoring, EC quantification, and embryotoxicity testing in Zebrafish. Four samples were taken from both rivers (July 2023, October 2023, February 2024, and May 2024), with four points in the RA (A1 to A4) and six in the RM (M1 to M6). EC analysis was conducted using liquid chromatography coupled with sequential mass spectrometry (LC-MS/MS). The embryotoxicity test was performed in accordance with OECD protocol N°236. Zebrafish embryos were exposed to water samples for 96 hours, and the effects indicative of lethality were evaluated after 24h. Morphological changes indicative of teratogenic effects were analyzed after 96h. Were quantified 8 and 23 EC classes in the RA and RM samples, respectively. The main classes with the highest total concentrations in the study were herbicides, pharmaceuticals, and industrial products. Among the 23 ECs found in the RM, 3 had concentrations above the maximum value allowed by the Conselho Nacional do Meio Ambiente (CONAMA) Resolution N°356/2005 for Class II fresh water, and another 16 are not regulated. Mortality was observed in half of the samples, while teratogenic effects occurred in all samples. The main effects identified were edema in the pericardium and yolk sac, scoliosis, tail curvature, delayed growth, absence of mouth, and uninflated swim bladder. These effects can compromise the survival of the embryo, leading to death. Thus, the quantification of EC and the observation of toxic and teratogenic effects in Zebrafish embryos exposed to the waters of the Pantanal in Mato Grosso do Sul indicate the influence of anthropic activities at the sites studied. These results highlight the need for environmental quality monitoring studies, in addition to political measures for the conservation of the biome.