This study assessed the concentrations of metals in the Dourados and Brilhante Rivers, investigated the influence of landscape features surrounding these rivers on water quality, and evaluated the risks associated with metal contamination for aquatic biota and human health. Sampling was conducted at eighteen sites distributed along the rivers in June 2016. The concentrations of metals (Cu, Zn, Mn, Fe, Cr, Al and Co) in the water were analyzed by inductively coupled plasma optical emission spectroscopy. All the samples possessed Fe concentrations above the threshold value for aquatic biota (0.3 mg L-1). Moreover, land use and land cover assessment of the study area revealed extensive agriculture activity, particularly in areas surrounding the Dourados River headwaters. Fe bioavailability for both rivers indicated risks for aquatic biota and human health. Overall, the elevated Fe content in these rivers was attributed to anthropogenic activity in the vicinity of these water bodies and the soil characteristics of the area. Considering the importance of river basins, it is necessary to implement public policies for their conservation, especially those related to the cultivation of forests of native species and sustainable agricultural practices, in addition to improving the effluent treatment infrastructure, which is essential to minimize the adverse effects of contamination by chemical elements in water bodies. Keywords: aquatic ecosystems, environmental contaminants, forest fragments.

The conversion of riparian forests into agricultural land results in the loss of water quality and aquatic biota health. The objectives of this study were therefore to determine the proportion of land use with emphasis on the type of vegetation cover; evaluate the limnological parameters and concentration of inorganic elements in the water of the São José stream in the Dourados River Basin, Mato Grosso do Sul, Brazil; correlate land use with the concentrations of inorganic elements in water; and evaluate the risk to preservation aquatic biota and in situ toxic effect on Astyanax lacustris. We collected samples from the São José Stream in 2020 and evaluated land use with high resolution aerial images. The inorganic elements in water samples were quantified using inductively coupled plasma optical emission spectrometry. In the surroundings of the São José stream, a reduction in riparian forest was observed with a proportion of only 16.32% of the area and the predominance of agricultural areas with 75.06%. The concentrations of dissolved oxygen (1.510 mg L-1) and P (> 0.235 mg L-1) in the water did not comply with the national legislation. In addition, Al and P indicated risks regarding the conservation of aquatic biota (risk quotient >1). The in situ evaluation of A. lacustris also revealed toxicity in the water. The results indicate environmental imbalance in the São José stream, requiring mitigation measures for its restoration and the sustainable use of its resources. Keywords: anthropic action, inorganic contaminants, risks for aquatic biota.

O acesso a água subterrânea ocorre principalmente por meio da perfuração de poços, sendo estes denominados cacimba ou tubulares. Estudos na literatura indicam que características relacionadas ao tipo e a profundidade de poços podem implicar na qualidade da água subterrânea. Nesse sentido, o objetivo do trabalho foi avaliar se o tipo e profundidade de poços influenciam nos efeitos citotóxicos, genotóxicos e mutagênicos de águas subterrâneas em células meristemáticas de Allium cepa. Dessa maneira, sementes de A. cepa foram submetidas a bioensaios com águas provenientes de 63 poços com diferentes tipos (cacimba e tubular) e profundidades (<5 até >15 m). Para avaliação dos efeitos citotóxicos foram calculados os Índice de Morte Celular (IMC) e Índice Mitótico (IM), e, para os genotóxicos e mutagênicos foram calculados o Índice de Alterações Cromossômicas (IAC) e o Índice de Mutagenicidade (IMT), respectivamente. Em relação ao tipo dos poços, foi observado efeito citotóxico para o parâmetro IM (p=0,02) para água proveniente de poço cacimba quando comparado com o tubular. Entretanto não foi observado efeito genotóxico quando os dois tipos foram comparados. É relevante destacar que a água oriunda de poços do tipo tubular induziu maior mutagenicidade (p=0,01) quando comparada aos poços cacimbas. Para a profundidade dos poços foi observado aumento de micronúcleos diretamente proporcional ao aumento da profundidade, sendo observada diferença significativa para os poços com >15 m. Dessa maneira, foi possível concluir que a água proveniente de poços cacimbas apresentou maior citoxicidade e a de poços tubulares e mais profundos (>15 m) apresentou maior mutagenicidade em células meristemáticas de A. cepa.