Ecotoxicidade de lixiviado de aterro sanitário utilizando minhocas e sementes como organismos-teste.

Abstract

Contamination of the terrestrial ecosystem caused by landfill leachate can cause irreparable damage to soil organisms, as well as to human health. Thus, the aim of this study was to determine the ecotoxicity of in natura landfill leachate using earthworms of the species Eisenia andrei and seeds of Solanum lycopersicum, Lactuca sativa and Brassica oleracea as test organisms. Leachate samples were collected at the Campina Grande Landfill, Paraíba, Brazil. The effluent ecotoxicity in Eisenia andrei earthworms was determined by means of lethality tests (preliminary, definitive and recontamination) and escape behavior; and in seeds by determining root growth, relative root growth, relative seed germination, germination index and EC50. The results showed that the leachate caused a lethal effect on earthworms from concentrations of 25% (26 mL.kg-1

), presenting a LC50 of 53% (55.06 mL.kg-1 ) for the

preliminary test and 56% (58.5 mL.kg-1

) for the definitive. Furthermore, it was observed that the higher concentrations caused deformations in the bodies of the organisms and behavioral change. The recontamination test did not show a high lethal effect, however, it caused serious damage to earthworms of the species Eisenia andrei, such as the stimulus to self-mutilation. The leakage test showed that all leachate concentrations in the soil, including the lowest (10 and 14%), caused the organisms to escape, with a loss of habitat in the pollutant concentration in 53.8% (55.8 mL .kg1

). The effluent phytotoxicity showed variations between the analyzed samples and between the species, whose species sensitivity scale was cabbage (EC50= 7.55%) < lettuce (EC50 = 8.52%) < tomato (EC50= 12.20%). It was also found that fresh leachate is more phytotoxic than preserved leachate, in which the preserved sample had an overestimated EC50 value. Regarding the test organisms used in this study, the three seed species were more sensitive than the earthworms, as they had lower EC50 values, which shows that the earthworms were more resistant to contamination. It was concluded that the leachate was toxic for the studied species, so that the use of test organisms proved to be excellent bioindicators of environmental contamination.