Toxicidade da água e sedimento do Córrego do Pântano, Alfenas - MG: um estudo temporal e espacial

Abstract

The domestic and industrial sewage coming from urbanized areas are often disposed in water bodies that surrounding them, contaminating them and inhibiting ability of ecosystems to maintain their natural processes. These contaminants tend to be transported over long distances or sediment, generating a new source of contamination. This study aimed to evaluate and monitor the phytotoxicity and genotoxicity of water and sediment of the Córrego do Pântano, which is exposed to discharges of domestic and industrial sewage. Water and sediment samples were collected monthly at five sites in the Córrego do Pântano, in the period October 2010 to July 2011. The levels of cadmium, lead and zinc of the samples were determined. Lactuca sativa seeds were exposed to water samples and aqueous extracts of the sediments and the parameters evaluated were the germination rate, root length, fresh and dry weight, mitotic index and frequency of chromosomal abnormalities. We observed high levels of cadmium and lead in water samples collected during the rainy months. The water samples and aqueous extracts of the sediments showed phytotoxic effect on germination and biomass of L. sativa. The root length was not affected and was stimulated for the samples. Only the water samples reduced the mitotic index and no effects on the frequency of chromosomal abnormalities were observed. For the phytotoxicity test was observed significant temporal variation related to rainfall, while for the cytogenetic assay was not observed pattern.