Induction of fish biomarkers by synthetic-based drilling muds

Physical and chemical characterization of drill cuttings: A review

Drill cuttings comprise a mixture of rocks generated during drilling activities of exploration and production of oil and gas. These residues' properties are variable, depending on several drilling parameters and drilled rock composition. Many scientific studies have been published regarding the characterization of these residues. Articles summarizing these residues' characteristics and toxicity data are poorly explored in the literature. This work reviews the principal methods used to characterize drill cuttings and data about these residues' properties. Some authors have reported the large content of Zn in drill cuttings. These cuttings can be associated with base fluids (as olefins, varying from C11 to C18), and some time crude oil (high range of TPH, unresolved complex mixtures, and PAH compounds). Acute and chronic toxicity tests have shown negative impacts of different types of fluids, the components of these fluids, and cuttings on other marine organisms.

Genotoxic and hematological parameters in Colossoma macropomum (Pisces, Serrasalmidae) as biomarkers for environmental impact assessment in a protected area in northeastern Brazil

Genotoxic and hematological parameters in tambaqui (Colossoma macropomum), a native freshwater fish, were used as biomarkers to assess exposure to environmental stressors within the Maracanã Protected Area of Maranhão State, Brazil. Fish were sampled at two sites-Serena Lagoon (control) and Ambude River-on four occasions (dry and rainy season), and biometric data (length and weight) recorded and blood collected from all fish for analysis. Erythrocyte indices-mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration-were calculated. Blood samples were stained with Giemsa and acridine orange, and microscopically examined for micronuclei and morphological nuclear abnormalities. Micronuclei were observed in fish from both sites, although the frequency was significantly higher in fish from the Ambude River and morphological nuclear abnormalities were only observed in fish from the Ambude River. More morphological nuclear abnormalities and a larger number of micronuclei were observed in erythrocytes stained with acridine orange compared with those stained with Giemsa. On average, erythrocyte indices were lower in fish from the Ambude River than from the Serena Lagoon. The results confirm that genotoxic and hematological parameters in C. macropomum can be used as indicators of environmental health and could be valuable tools for monitoring environmental conditions within protected areas.