Integrated environmental assessment of iron ore tailings in floodplain soils and plants after the Fundão Dam disaster in Brazil.

Previous studies of the Doce River basin (Brazil) seem to be contradictory regarding the contamination of soils with potentially harmful elements (PHE). This research aimed to perform an integrated assessment of PHE in the soil-plant-tailing system from the area most affected by the iron waste after the Fundão Dam disaster in 2015. Different fractions of PHE (exchangeable, nonexchangeable, reducible, and pseudo-total) were determined on deposited iron waste (DIW), soil waste mixture (SWM), and control soil (CS) samples. Total contents of PHE in Poaceae were also determined, and Allium cepa bioassays were performed to determine DIW and CS cytotoxicity and/or genotoxicity to plants. The Fe and Mn contaminations were the only ones related to the deposition of DIW on floodplains, and other harmful element content (such as As, Hg, Ni, Cd, Cr, and Pb) was not found above baseline values for soils. In addition, a significant part of the Fe and Mn in DIW is readily available or subject to acidification and prolonged flood reduction processes. The high available content of Fe favored its excessive accumulation by Brachiaria. The DIW chemical conditions reduced biological functions of A. cepa under a controlled environment. However, more drastic effects, such as genetic damage, were not seen. The postdisaster action of covering DIW with CS resulted in undesirable enrichment of Pb on the floodplain soils. The integrated results allow the conclusion that the iron waste is not a time bomb for PHE contamination of soils between the Fundão and Risoleta Neves Hydroelectric Dam (~100 km away from Fundão). Integr Environ Assess Manag 2024;20:117-132. © 2023 SETAC.

Evaluation of the water quality of the upper reaches of the main Southern Brazil river (Iguaçu river) through in situ exposure of the native siluriform Rhamdia quelen in cages.

Increase in industrial growth, urban and agricultural pollution, with consequent impacts on aquatic ecosystems are a major focus of research worldwide. Still, not many studies assess the impacts of contamination through in situ studies, using native species, also considering the influence of seasonality on their responses. This study aimed to evaluate the water quality of the basin of the Upper Iguaçu River, the main source of water supply to Curitiba, a major capital of Southern Brazil, and its Metropolitan area. Several biomarkers were evaluated after in situ exposure of the native catfish Rhamdia quelen inside cages for 7 days. Ten study sites were chosen along the basin, based on a diffuse gradient of contamination, corresponding to regions upstream, downstream, and within "great Curitiba". In each site, fish were exposed in Summer and Winter. The complex mixture of contaminants of this hydrographic basin generated mortality, and ion-, osmoregulatory and respiratory disturbances in the catfish as, for example, reduction of plasma osmolality and ionic concentrations, increased hematocrit levels and gill water content, altered branchial and renal activities of the enzyme carbonic anhydrase, as well as raised levels of plasma cortisol and glucose. Biomarkers were mostly altered in fish exposed in Great Curitiba and immediately downstream. There was a notable influence of season on the responses of the jundiá. A multivariate redundancy analysis revealed that the best environmental variables explained 30% of the variation in biomarkers after controlling for spatial autocorrelation. Thus, this approach and the chosen parameters can be satisfactorily used to evaluate contamination environments with complex mixtures of contaminants, in other urban basins as well.

A multibiomarker evaluation of urban, industrial, and agricultural exposure of small characins in a large freshwater basin in southern Brazil.

Iguaçu River is the second most polluted river of Brazil. It receives agrochemicals and contaminants of urban and industrial sources along its course. A multibiomarker approach was employed here to evaluate the health of a small characin (Astyanax spp.) at two sites along the river, sampled during a dry (autumn) and a rainy (spring) season. Biomarkers were condition factor and somatic indices (gonads and liver); genetic damage (comet assay and micronucleus test); enzyme activities such as hepatic catalase (CAT) and glutathione S-transferase (GST), lipoperoxidation (LPO), branchial and renal carbonic anhydrase (CA), acetylcholinesterase (AChE) in the muscle and the brain, histopathology of the liver and gills, and concentrations of polycyclic aromatic hydrocarbons (PAHs) in bile. There were no consistent differences in biomarker responses between the two study sites. Some biomarkers revealed greater potential impact in the rainy season, when increased amounts of contaminants are washed into the river (combined CAT inhibition and LPO increase, CA upregulation). Other biomarkers, however, revealed potential greater impact in the dry season, when contaminants potentially concentrate (GST induction, AChE inhibition, and liver histopathological alterations). Although of a complex nature, field experiments such as this provide rich data for monitoring protocols and assessment of general risk of exposure to pollutants of river systems.

Composição e estrutura da ictiofauna da Estação Ecológica do Caiuá, área de influência da UHE de Rosana (rio Paranapanema), sudeste do Brasil / Composition and structure of the ichthyofauna of the Estação Ecológica do Caiuá, area influenced by Rosana reservoir (Paranapanema river), southeastern Brazil / Contribución y estructura de la fauna de peces de la estación ecológica del caiuá, area sobre influencia de la uhe de rosana (río paranapanema), sudeste de Brasil

Foi estudada a composição e estrutura da ictiofauna em uma área influenciada pelo reservatório da UHE de Rosana, dentro dos limites da Estação Ecológica do Caiuá, no Paraná. As amostragens foram realizadas entre agosto de 1997 e dezembro de 1998 e resultaram em 793 indivíduos pertencentes a 30 espécies de peixes e 16 famílias, sendo Anostomidae (sete espécies), Pimelodidae (três espécies), Serrasalmidae (três espécies) e Loricariidae (três espécies) as mais representativas. A ictiofauna foi representada por peixes de pequeno (< 20cm), médio (entre 20 e 40cm) e grande porte (>40cm). A maior parte das espécies de ocorrência generalizada na bacia foi freqüente nas amostragens e as contribuições em biomassa e número de indivíduos parecem indicar uma instabilidade no reservatório, em função das alterações na abundância, substituições de espécies e predomínio de oportunistas. Esta constatação, somada ao fato da abundância da espécie exótica Plagioscion squamosissimus nas capturas, indica que as medidas de manejo da Estação Ecológica devem priorizar a proteção dos recursos naturais em toda bacia hidrográfica.

ABSTRACT: The composition and structure of the ichthyofauna in one area infl uenced by the Rosana Reservoir, inside of the Estação Ecológica do Caiuá in the State of Paraná, were studied. The catches were made from August/1997 to December/1998, and resulted in 793 fi sh belonging to 30 species and 16 families. The families Anostomidae (seven species), Pimelodidae (three species), Serrasalmidae (three species) and Loricariidae (three species) were the most representatives. The ichthyofauna was composed by small (< 20cm), medium size (between 20 and 40cm) and large fi sh (>40cm). The most common group of fi sh in catches are found widespread in the Paraná River Basin, and its biomass and number of fi sh contributions seems to indicate that the dammed area is still instable, because of their abundance and richness variations, and high contributions of that with opportunistic strategies. Based on these results, and in the abundance of the exotic fi sh Plagioscionsquamosissimus, the management strategies of the conservation unit should protect the natural resources in the entire river basin.

RESUMEN: Se estudió la composición y estructura de la fauna de peces en un área infl uenciada por la Represa de Rosana, dentro de la Estación Ecológica Caiuá en el Estado de Paraná, Brasil. Las capturas fueron hechas de agosto/1997 hasta diciembre/1998, y se identifi caron 793 peces pertenecientes a 30 especies y 16 familias. Las familias Anostomidae (siete especies), Pimelodidae (tres especies), Serrasalmidae (tres especies) y Loricariidae (tres especies) fueron las más representativas. La fauna estuvo compuesta por peces de pequeño (<20cm), medio (entre 20 y 40cm) y grande (>40cm) tamaños. El grupo más común en las capturas se encuentra distribuido en la cuenca del río Paraná y su biomasa y número de individuos parecen indicar que el área represada todavía es inestable, debido a sus variaciones de abundancia y riqueza, y contribuciones altas de aquellas conocidas como oportunas. Basado en estos resultados, y en la abundancia del pez exótico Plagioscionsquamosissimus, las estrategias de manejo de la unidad de conservación deben proteger los recursos naturales en toda la cuenca hidrográfica.