Testes ecotoxicológicos como ferramenta na avaliação da poluição ambiental causada por aterros comuns (ou lixões): o caso do riacho dos cavalos em Crateús-CE

Abstract

The generation of solid waste is not a one-off problem, but a dynamic process that reflects the behavior and consumption capacity of a population. Excessive generation, combined with inadequate disposal, has become a problem in most Brazilian municipalities. In the municipality of Crateús - CE, this reality is no different. The urban solid waste collected has as its final destination the dump (uncontrolled landfill) which is located on the banks of Riacho dos Cavalos, one of the main tributaries of the Poti River, possibly causing soil contamination and, consequently, affecting water quality. . Thus, the present study intends to evaluate the occurrence of toxicity in the water of Riacho dos Cavalos through ecotoxicological tests using the model organism Cucumis sativus L. (cucumber), with the general objective of obtaining a probable contamination potential of this source caused by the action of leached liquids from the landfill. The research methodology consisted of conducting field research, of an exploratory nature, including on-site visits to collect water samples, followed by the use of photographic records in order to characterize the location to verify the proper influence of the dump on water quality of Cavalos Creek. In the ecotoxicological tests with Cucumis sativus L., the methodology consisted of placing the seeds in Petri dishes, with filter paper substrate and moistened with 5 ml of each sample, under a controlled temperature of 20 ± 1 oC for a period of 120 h. At the end of the incubation period, germination parameters, radicle and hypocotyl length of seedlings were evaluated. From the measurements, the mean, standard deviation, analysis of variance (ANOVA), germination index (GI), normalized residual germination percentage index (IGN) and the normalized residual radical elongation percentage index (IER) were calculated. The results of the bioassays showed a moderate level of toxicity for the point closest to the landfill area, identified through the inhibition of radicle and hypocotyl growth for the tested species. However, in general, the toxicity tests indicated low acute toxicity in the other points. Therefore, further studies are recommended, such as, for example, the use of other more sensitive model organisms or the use of chronic or subchronic tests, in addition to carrying out the physical-chemical characterization of the Riacho dos Cavalos water.