Approved Abstracts

Spatiotemporal variations of biliary polycyclic aromatic hydrocarbons metabolites in edible fishes from the Doce River Basin after the Fundão tailings dam collapse

Presenter: Larissa Ajala Batista

A wide variety of anthropic activities are performed along the Doce River Basin (DRB), including mining, dumping of industrial waste, fossil fuel burning, agricultural run-off, and disposal of raw sewage into water bodies. Hence, a combination of toxicants is constantly released as a result of the intense historical and current exploitation of DRB’s natural resources. The collapse of the Fundão tailings dam, in 2015, has worsened the problem of the basin by unleashing a massive amount of iron ore waste approximately 670 km downstream and therefore posing major socioeconomic and environmental challenges in the area. Besides the input from the dam, it has been suggested that the plume of mud resuspended many hazardous substances, including polycyclic aromatic hydrocarbons (PAHs), which have been given prime attention worldwide due to their ubiquitous occurrence, persistence, and potential to give rise to a series of detrimental effects on biota. In fish, these xenobiotics have been shown to induce adverse effects from embryos to reproducing adults (e.g., affecting their behavior, growth, and survival, promoting an increase in tumorigenesis, spinal deformities, ovotestis formation, and testicular hypoplasia, as well as decreasing the number of ovarian mature follicles). Therefore, this study investigates spatiotemporal variations in concentrations of biliary PAHs metabolites in edible demersal (Rhamdia quelen and Pimelodus maculatus) and pelagic (Astyanax lacustris and Geophagus brasiliensis) fishes from the DRB, this being the first study to investigate PAHs in different fish species from the DRB post-disaster. Samples were obtained from the upper, middle, and lower sectors of the basin during the rainy and dry seasons of 2019. Concentrations of distinct groups of PAHs, ranging from two to six-ring compounds, were estimated by fluorescence spectroscopy through different excitation/emission wavelengths in a microplate spectrophotometer. We used generalized linear mixed models (GLMMs) to compare the distribution of PAH metabolites in fishes sampled in different sectors and seasons, with sampling location as a random effect. The ratio of total concentrations of low-molecular-weight (LMW)/high-molecular-weight (HMW) PAHs was applied to preliminary distinguish between petrogenic and pyrogenic sources across the DRB. PAHs from our study area presented both petrogenic (LMW) and pyrogenic (HMW) origins, the former being predominant in all sampled species, sectors, and seasons. Concentration and chemical structure profiles of biliary PAH changed within and between species, as well as across sectors and seasons, leading to unequal distributions. Particularly, A. lacustris showed the highest concentrations for 6, 5, and 4- ring PAH and the lowest for 2-ring, while R. quelen displayed the highest values for 2-ring PAH and the lowest ones for all the others. G. brasiliensis and P. maculatus showed intermediate values. Between sectors, the only difference was found for G. brasiliensis during the wet season and 5-ring (higher in the middle compared to the lower sector). Since all four species presented both low and HMW PAHs, the analysis of PAH metabolites in fish bile may be used as a preliminary assessment of these toxicants in future studies from the study area. We hypothesize that a range of factors may be underpinning biliary PAH distributions in fishes from the DRB, including, but not limited to, local and regional sources as well as local and long-range transport of PAHs, precipitation patterns, and susceptibility differences among species. Further research is warranted to detect these contaminants in edible fish tissues because of the imminent risk of contamination through consumption. This study received financial support from the Brazilian Education Council and the Fundação de Amparo à Pesquisa do Estado de São Paulo.

Keywords: Pollution; Reproduction; Toxic




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