Approved Abstracts

ECOTOXICITY OF NATURAL FRESHWATER SOURCES AND THE ADJACENT SOIL IN AGRICULTURAL AREAS IN THE SOUTH OF BRAZIL



Author(s): Cardozo, B; Gomes, EMV; Dusman, E; Rauen, TG;
Presenter: Thalita Grando Rauen

Agricultural activities are strongly related to the environment, causing changes in the soil and water resources. The consumption of water from wells and springs is a common practice in smallholdings in the South Region of Brazil and often occurs in areas used for the cultivation of crops. Thus, the monitoring of these water sources is required in order to measure the toxic effects of agricultural activities on the environment and thereby preserve the health of those who are dependent on this activity. In this context, the objective of this study was to investigate the ecotoxicity of water resources and their adjacent soils. Three agricultural areas were selected for this study, with one located in each of the three southern states of Brazil (Paraná-PR, Santa Catarina-SC, Rio Grande do Sul-RS). Water and soil samples were collected four times during the period of one year, with one collection per season. The ecotoxicological monitoring was carried out by way of cytotoxicity and mutagenetic tests on Allium cepa and bioluminescent bacteria Vibrio Fischeri (Microtox® System). The tests conducted with A. cepa demonstrated that soils adjacent to water resources in Paraná (winter) and Santa Catarina (summer) present cytotoxicity. The toxicity of the sample from PR was found to be related to high iron concentrations in the soil. Mutagenicity was not observed for any of the samples tested, although an increase in the mutagenicity index was noted for the samples from PR (fall) and RS (summer), presenting a significant negative correlation with the cation exchange capacity (CEC). The cytotoxicity test carried out with A. cepa using water samples did not show cytotoxic effects for any of the samples analyzed. However, the inhibition of cell division was observed after exposure to the samples from PR (summer) and RS (fall), when compared to the negative control (72 h) and to the control bulb (0 h), and an increase in cell division was observed for the sample from SC (spring). The test did not show a mutagenic effect for the water samples from RS (spring and summer). In the test with V. fischeri carried out using the Microtox ® system, the highest toxicity was found for the water sample from PR (spring), with a CE50 value of 15.51%, and the lowest toxicity was observed for the water sample from SC (spring), with a CE50 value of 538.1%. The integration of soil and water analyses highlighted the fragility of these water sources, which presented changes in their characteristics following the most intense cultivation period of the crops. This type of study is of great importance to verify the environmental quality of natural water resources under the influence of anthropogenic activities, allowing the evaluation and implementation of measures to protect the quality of freshwater.

Keywords: natural freshwater; agricultural area; seasonality

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