Biomonitoring of emerging contaminants in a river in southern Brazil

The Brazilian biomes degradation puts the quality and integrity of aquatic ecosystems at risk. The disorderly advancement of human activities such as industry, livestock and agriculture make water resources vulnerable to contamination. In this way, the use and occupation of land in the river catchment directly reflects the possible contaminants that may be detected in surface waters. The Uruguay River catchment comprises the Pampa and Atlantic Forest Biomes in southern Brazil, in addition to parts of Argentina and Uruguay. It is estimated that there is a small portion of vegetation remaining in relation to the initial vegetation cover in this catchment, with a high fragmentation degree, due to intense degradation. Therefore, the objective of this study is to evaluate the emerging contaminants presence in the Uruguay River and biomarkers in fish Astyanax sp. exposed to the mixture of these contaminants in situ. To this end, samples of water, sediment and fish were collected over a year in 5 locations distributed along the Uruguay River (around 300km). The occurrence of metals, pesticides, medicines for human and animal use and hormones in water samples was analyzed, and the presence of pesticides in sediments and fish muscles. The presence of 14 active pesticide ingredients was detected, the insecticide imidacloprid being the most common, 13 medicines, 1 female hormone and 7 metals in the water. The presence of 4 pesticides and 3 pesticides bioaccumulated in the fish muscles were detected in the sediments. The results obtained in this study are extremely important for evaluating the contamination of a river basin of international importance. With this, it is possible to determine the possible river contamination sources, and, thus, define or propose improvements in management and mitigation measures aimed at improving environmental quality.