Uso de hortaliças como bioindicadores para ensaios fitotóxicos agudos e crônicos do lixiviado de aterro sanitário

Abstract

Faced with the growing demand for the replacement or reduction of animal use in experimentation, there has been a considerable increase in the use of alternative test organisms in ecotoxicological tests. It has become necessary to develop research aimed at introducing plants as bioindicators for monitoring environmental pollutants. Therefore, this research aimed to evaluate the use of vegetables as bioindicators in acute and chronic phytotoxicity assays and the effects on cultivation irrigated with raw sanitary landfill leachate at different dilutions. In the acute phase, seeds of Lettuce (Lactuca sativa), Arugula (Eruca sativa), Watercress (Barbarea verna), Tomato (Solanum Lycopersicum), Cucumber (Cucumis sativus), Radish (Raphanus sativus), and Cabbage (Brassica oleracea) were used to evaluate radicle growth (RG), germination index (GI), and determine the EC50 (effective concentration at 50%). In the chronic phase, the most resistant vegetables identified in the acute phase were used to evaluate possible sublethal effects on plant growth, physiology, and biomass production through irrigation with raw leachate at different dilutions. Chemical characteristics of the soil after cultivation were also assessed. The results indicated an acute phytotoxic effect of the effluent on all seeds investigated; however, cucumber (Cucumis sativus) was the most resistant with an EC50 of 11.70%, and watercress (Barbarea verna) was the most sensitive with an EC50 of 2.20%, as analyzed from the sensitivity curve of the seeds. After cultivating cucumber (Cucumis sativus) and radish (Raphanus sativus) irrigated with raw leachate at 25% and 10% dilutions, the soil exhibited salinity and compaction characteristics, and chronic phytotoxic effects were observed in the plants, with reductions of approximately 50% and 70%, respectively, in vegetable growth and biomass, regardless of the dilution percentage of the raw leachate. The results also suggested a possible influence of hormesis effects on the physiological data of both irrigated crops. It was concluded that the bioindicator vegetables investigated in this research are sensitive to the toxicity of industrial (or recalcitrant) effluents and can be used in acute and chronic phytotoxicity bioassays, promoting their integration into routine environmental diagnostics.