Bioavailability of pollutants sets risk of exposure to biota and human population in reservoirs from Iguaçu River (Southern Brazil)

Abstract

The Iguaçu River, located at the Southern part of Brazil, has a great socioeconomic and environmental importance due to its high endemic fish fauna and its potential to generate hydroelectric power. However, Iguaçu River suffers intense discharge of pollutants in the origin of the river. In a previous report, the local environmental agency described water quality to improve along the river course. However, no study with integrated evaluation of chemical analysis and biological responses has been reported so far for the Iguaçu River. In the current study, three different Brazilian fish species (Astyanax bifasciatus, Chrenicicla iguassuensis, and Geophagus brasiliensis) were captured in the five cascading reservoirs of Iguaçu River for a multi-biomarker study. Chemical analysis in water, sediment, and muscle indicated high levels of bioavailable metals in all reservoirs. Polycyclic aromatic hydrocarbons (PAHs) were detected in the bile of the three fish species. Integration of the data through a FA/PCA analysis demonstrated the poorest environmental quality of the reservoir farthest from river's source, which is the opposite of what has been reported by the environmental agency. The presence of hazardous chemicals in the five reservoirs of Iguaçu River, their bioaccumulation in the muscle of fish, and the biological responses showed the impacts of human activities to this area and did not confirm a gradient of pollution between the five reservoirs, from the source toward Iguaçu River's mouth. Therefore, diffuse source of pollutants present along the river course are increasing the risk of exposure to biota and human populations.

Fish fauna in forested and rural streams from an ecoregion of high endemism, lower Iguaçu River basin, Brazil

“…Despite of fish fauna singularities, the high stretches of Iguaçu River basin have been hardly impacted by industrial and urban pollution (Agostinho & Gomes 1997, Yamamoto et al 2016, while hydroelectric dams, constructed in cascades, represent the main threat to fish fauna at the lower Iguaçu River and its tributaries (Agostinho et al 2008(Agostinho et al , 2016. The construction of the low Iguaçu dam at its last segment above the falls (ANEEL 2017), has imminent potential to negative impacts, both on the endemic fishes and on the boundaries of Iguaçu National Park (UNESCO 2012).…”

“…Due to the historical process of land use and occupation, these streams present different percentages of vegetal cover among their watersheds. The use gradient extends from rural streams, with intense agricultural activity (IBGE 2015, Yamamoto et al 2016, to preserved streams located partially or integrally within conservation units, like those into the Iguaçu National Park (INP) (Neves et al 2015).…”

Histopathological alterations in Astyanax bifasciatus (Teleostei: Characidae) correlated with land uses of surroundings of streams

“…A recent study by Yamamoto et al (2016) correlated the presence of metals and other contaminants in the water and sediment in five cascading reservoirs in the Iguaçu River. The responses of multi-biomarkers (including the presence of metals in muscle and aromatic polycyclic hydrocarbons in the bile) in the same species evaluated here were consistent with a higher level of fish exposure to domestic and industrial effluents from the metropolitan region of Curitiba (upstream), as well as from agricultural areas in reservoirs located further downstream, close to the study area (Yamamoto et al, 2016). In this context, the significant differences between the responses of fish of the forest (control) streams and the others support the evidence that the histological alterations verified here result from the presence of irritants in the water of the streams under intense land uses in the surroundings.…”

“…Despite being fundamental for the water supply of various cities and agricultural areas (Pereira, Scroccaro, 2010) as well as presenting high endemism of its fauna (Nogueira et al, 2010;Baumgartner et al, 2012), the Iguaçu River basin is highly impacted. At its higher and medium parts, the pollutants are derived mainly from urban and industrial sewage (Yamamoto et al, 2016), while in its lower part, the western part of the state, the principal contaminants are agricultural pesticides based on organophosphates and carbamates (Freire et al, 2015). In this sense, the biomonitoring of water bodies in order to assess environmental quality becomes extremely important, since these xenobiotics can pass by biotransformation in individuals or biomagnification in levels of the food web, thus compromising the entire ecosystem (Silva et al, 2013).…”

Vulnerabilidades en salud de garimpeiros de una región amazónica

“…Um dos agravantes do uso indiscriminado dos metais é o risco envolvido ao serem lançados em grande quantidade no meio ambiente ou durante o processo de extração, que pode atingir diretamente o trabalhador desse setor, o garimpeiro. 1 Esse trabalhador, por vezes, devido às condições de insegurança nas quais desempenha suas atividades, torna-se susceptível a diversas formas de violência e adoecimentos, e como agravante, pela falta de proteção ao exercício trabalhista, comumente sem amparo legal amplia sua situação de vulnerabilidade em saúde, ou seja, aumenta seu potencial de adoecimento. 2 O atendimento das necessidades do extrativista mineral e de seus familiares não ocorre em sua integralidade, conservando desigualdades históricas que afastam esses trabalhadores de melhores condições de vida e possibilidades de escolhas, logo, implicando em prejuízos para o desenvolvimento humano.…”