Cytotoxicity and mutagenicity of the waters of the Marrecas River (Paraná, Brazil) to bullfrogs (Lithobates catesbeianus)

Biochemistry biomarkers and metal levels as indicators of environmental pollution in Danio rerio exposed to the Sorocaba River (S.P.), Brazil

Metal contamination of the environment poses a significant threat to human health and can cause significant damage to aquatic ecosystems. Danio rerio was exposed to Sorocaba River water for 96 h from two different sites in summer (S) and winter (W). Concentrations of Al, Cd, Cu, Mn and Zn were determined in the exposure water and in sediment. At the end of the exposure, the concentrations of Al, Cu and Mn at the Ibiúna point (P1) and Mn at the Itupararanga point (P2) decreased compared to the initial concentrations in the water. In summer and winter, the highest concentrations of Cu and Mn were found in the sediment. Exposure to the Sorocaba River water caused various responses both in summer and winter. For example, GPx decreased in winter, Glutathione S-Transferase (GST) increased in summer, and Nitric Oxide Synthase (NOS) decreased in both seasons in the viscera. In winter, SOD Superoxide Dismutase (SOD) increased, while GPx and GST (winter) decreased in muscle; regarding viscera carbonyl proteins, there was an increase in the summer at P2. Acetylcholinesterase activity decreased in the brain in winter at P2 and NOS decreased in the summer-exposed groups and increased in the winter P2-exposed group. Lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) decreased in viscera (S, P1) and increased in muscle (S, P1 and P2). The glucose and triglycerides increased in muscle, both in summer and winter. Correlation analysis revealed associations between biomarkers from different organs. These alterations suggest that the fish experienced oxidative stress in response to exposure to the Sorocaba River, contaminated with metals, highlighting their vulnerability to environmental pollutants.

Genotoxicity of surface waters in Brazil

Brazil has abundant surface water resources, huge aquatic biodiversity and is home to 213 million people. Genotoxicity assays are sensitive tools to detect the effects of contaminants in surface waters and wastewaters, as well as to determine potential risks of contaminated waters to aquatic organisms and human health. This work aimed to survey the articles published in 2000-2021 that evaluated the genotoxicity of surface waters within Brazilian territory to unveil the profile and trends of this topic over time. In our searches, we considered articles focused on assessing aquatic biota, articles that conducted experiments with caged organisms or standardized tests in the aquatic sites, as well as articles that transported water or sediment samples from aquatic sites to the laboratory, where exposures were performed with organisms or standardized tests. We retrieved geographical information on the aquatic sites evaluated, the genotoxicity assays used, the percentage of genotoxicity detected, and, when possible, the causative agent of aquatic pollution. A total of 248 articles were identified. There was a trend of increase in the number of publications and annual diversity of hydrographic regions evaluated over time. Most articles focused on rivers from large metropolises. A very low number of articles were conducted on coastal and marine ecosystems. Water genotoxicity was detected in most articles, regardless of methodological approach, even in little-studied hydrographic regions. The micronucleus test and the alkaline comet assay were widely applied with blood samples, mainly derived from fish. Allium and Salmonella tests were the most frequently used standard protocols. Despite most articles did not confirm polluting sources and genotoxic agents, the detection of genotoxicity provides useful information for the management of water pollution. We discuss key points to be assessed to reach a more complete picture of the genotoxicity of surface waters in Brazil.

Effect of elemental composition assigned to antrotopic pollution on the quality of the water and sediment of the Marrecas river (PR, Brazil) as highlighted by multivariate statistical analyses

In recent years, several environmental pollutants have been monitored in surface waters and sediments. However, few studies apply multivariate statistics to identify the main components and correlate them temporally and spatially. In this sense, the present study sought to monitor the quality of water and sediments in the Rio Marrecas/Brazil, through the analysis of physicochemical parameters and trace elements, as well as to identifying sources of contamination, using multivariate statistics. For this purpose, sampling was carried out in nine locations for a period of 12 months. The Total Reflection X-ray Fluorescence (TXRF) technique was used to quantify the 15 elements identified in water and sediment samples. Through multivariate statistical analyses, the most significant elements, their correlations and possible pollutant sources were defined, and the pollution index (HPI) and assessment index (HEI) of heavy metals were applied. The parameters pH and BOD₅ do not comply with Brazilian legislation. Based on PCA and Spearman correlation, there was strong evidence of contamination of the water naturally, composed of the elements Ti, V, Mn, Fe, and of anthropogenic origin composed of the elements Ca, Ni, Cu, Zn. These findings provide insights to determine the impacts of heavy metals on human health and the environment.