RESUMO

Environmental impacts caused by mine dam ruptures or inappropriate tailing depositions represent a global concern. An ecological risk assessment was performed in 18 areas affected by the collapse of a major mining dam in southeastern Brazil, in two monitoring periods (2015 and 2018). In these areas, pedogeochemical surveys, and ecological risk levels were determinate. In addition, ecotoxicological assays with Proisotoma minuta (Collembola) were carried out in laboratory. Soil screening values indicated that all contaminated areas were above regional reference values for soil quality for at least one metal (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), likewise exceeding threshold values for potential ecological and human health risks. In two monitoring years, significant ecotoxicity in the avoidance and reproduction of P. minuta (> 60 % and >80 %, respectively) were evidenced in most soils; and lethal responses in some areas like Córrego Novo, Governador Valadares and Tumiritinga. Results suggest changes in soil physical-chemical properties due to tailing deposition, thus affecting soil dwellers. This study can elucidate the use of appropriate tools to ecological risk assessments, helping to identify the priority areas for defining remediation and monitoring strategies.

Assuntos

RESUMO

The scaling-up of lindane-contaminated soils bioremediation from microcosms to mesocosms bioaugmentated with an actinobacteria quadruple culture and biostimulated with sugarcane filter cake (SCFC) was surveyed. Mesocosms of silty loam soil, clayey soil, and sandy soil were polluted with the pesticide, bioaugmented with the mixed culture, biostimulated with adequate amounts of 0.5 mm SCFC particles, and assessed during 63 days maintaining environmental parameters with minimal intervention. Samples were taken to determine residual lindane, heterotrophic microorganisms, enzymatic activities, and bioremediation effectiveness using ecotoxicity tests with Raphanus sativus, Lactuca sativa, and Lycopersicon esculentum. The bioaugmentation and biostimulation of the three soils improved lindane removal, microbial counts, and enzymatic activities, and reduced pesticide T1/2, regarding the values obtained in non-bioremediated controls. The removal process was significantly affected by the soil type, and the highest pesticide dissipation (82.6%) was detected in bioremediated sandy soil. Ecotoxicity tests confirmed the bioremediation success through a rise in the vigor index of seedlings compared to non-treated soils (R. sativus: 12-22%; L. sativa: 12-20%; L. esculentum: 30-45%). Finally, scanning electron microscopy corroborated soil colonization by actinobacteria. Successful scaling-up of the combined application of an actinobacteria quadruple culture and SCFC as an appropriate strategy for restoring lindane-polluted soils at mesocosms-scale was confirmed.

Assuntos

RESUMO

This study evaluated the efficiency of two bioindicators, fecal coliforms and ecotoxicity tests, set out in CONAMA Resolution 274/00 and CONAMA Resolution 357/05, in assessment of water quality. For this study, Lake Paranoá, Federal District of Brazil, was chosen, since it is a water body directly contaminated by effluents from a sewage treatment plant. Four sampling points were chosen in accordance with the map of recreational water quality published weekly by CAESB/DF, after analysis of fecal coliforms. Samples from these points were collected for 6 months and tested on Danio rerio fish (acute toxicity) and on the microcrustacean Ceriodaphnia dubia (acute and chronic toxicity), besides measuring chemical and physico-chemical parameters. The data obtained show great consistency between the observed biological parameters, suggesting that in this urban aquatic environment, under great anthropogenic pressure, the fecal coliform bioindicator seems to be more restrictive and enough to evaluate the safety of surface water.

Este trabalho comparou a eficiência dos bioindicadores coliformes fecais ou termotolerantes e ensaios de ecotoxicidade, propostos pelas Resoluções Conama 274/00 e Conama 357/05, na avaliação da qualidade de água. Para a realização desse estudo foi escolhido o Lago Paranoá, Brasília, Distrito Federal, por ser um corpo hídrico impactado diretamente pelo lançamento de efluentes de uma estação de tratamento de esgotos. Foram definidos quatro pontos de acordo com o mapa de balneabilidade, publicado semanalmente pela Caesb/DF, em função do teor de coliformes termotolerantes. Amostras desses pontos colhidas durante seis meses foram testadas com o peixe Danio rerio (toxicidade aguda) e o com o microcrustáceo Ceriodaphnia dubia (toxicidade aguda e crônica), além da determinação de parâmetros químicos e físico-químicos. Os resultados obtidos mostraram grande equivalência entre os parâmetros biológicos observados, sugerindo que nesse ambiente sob grande influência antrópica, o bioindicador coliformes termotolerantes foi mais restritivo e suficiente para avaliar a segurança das águas superficiais.

Assuntos

RESUMO

This study evaluated the efficiency of two bioindicators, fecal coliforms andecotoxicity tests, set out in CONAMA Resolution 274/00 and CONAMA Resolution357/05, in assessment of water quality. For this study, Lake Paranoá, Federal District ofBrazil, was chosen, since it is a water body directly contaminated by effluents from a sewagetreatment plant. Four sampling points were chosen in accordance with the map ofrecreational water quality published weekly by CAESB/DF, after analysis of fecal coliforms.Samples from these points were collected for 6 months and tested on Danio rerio fish (acutetoxicity) and on the microcrustacean Ceriodaphnia dubia (acute and chronic toxicity), besidesmeasuring chemical and physico-chemical parameters. The data obtained show greatconsistency between the observed biological parameters, suggesting that in this urbanaquatic environment, under great anthropogenic pressure, the fecal coliform bioindicatorseems to be more restrictive and enough to evaluate the safety of surface water.(AU)

Este trabalho comparou a eficiência dos bioindicadores coliformes fecais ou termotolerantes eensaios de ecotoxicidade, propostos pelas Resoluções Conama 274/00 e Conama 357/05, naavaliação da qualidade de água. Para a realização desse estudo foi escolhido o Lago Paranoá,Brasília, Distrito Federal, por ser um corpo hídrico impactado diretamente pelo lançamentode efluentes de uma estação de tratamento de esgotos. Foram definidos quatro pontos deacordo com o mapa de balneabilidade, publicado semanalmente pela Caesb/DF, em funçãodo teor de coliformes termotolerantes. Amostras desses pontos colhidas durante seis mesesforam testadas com o peixe Danio rerio (toxicidade aguda) e o com o microcrustáceoCeriodaphnia dubia (toxicidade aguda e crônica), além da determinação de parâmetrosquímicos e físico-químicos. Os resultados obtidos mostraram grande equivalência entre osparâmetros biológicos observados, sugerindo que nesse ambiente sob grande influênciaantrópica, o bioindicador coliformes termotolerantes foi mais restritivo e suficiente paraavaliar a segurança das águas superficiais.(AU)

Assuntos