Análise de hidrocarbonetos e elementos traço em tecidos de tartarugas marinhas no nordeste do Brasil

Abstract

In the second semester 2019, it was documented the largest oil spill registered in Northeast coast of Brazil, an essential environment for reproduction and development of for sea turtles. Direct or indirect contact with substances present in petroleum can cause several health damages, such as the inefficiency of vital organs due to the bioaccumulation of toxic compounds. Hydrocarbons and trace elements are some substances present in the oil which can bring serious risks to the organisms, bioaccumulating, which in the process of transferring of nutrients, can cause damage to the whole the biodiversity. Therefore, the objective of this work is to do a qualitative and quantitative analysis of hydrocarbons and trace elements in different tissues of stranded sea turtles on the coast of Northeast Brazil, before (2016-2018) and after (2020-2021) the environmental disaster of the oil spill. 44 stranded sea turtles were collected in the coast of Northeast of Brazil between 2016 and 2018 (Group 1) and 38 were collected enter 2020 and 2021 (Group 2). All the individuals of Group 1 are Chelonia mydas and averages of 61.65 cm and 57.65 cm for the Length Curvature Carapace (LCC) and Width Curvature Carapace (WCC). In Group 2, 79% are Chelonia mydas, 15% Lepidochelys olivaceae and 11% Caretta caretta. LCC and WCC for this group presented means of 61.65 cm and 57.64 cm. The animals were dissected and was collected the liver and peitoral muscle. The samples were homogenized and stored in glasses recipients. The samples from Group 2 were send to laboratory where the analysis of polycyclic aromatic hydrocarbons was performed by the Sohxlet extraction and gas chromatography and the quantification of the elements Al, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb and Zn was performed through wet digestion and plasma-coupled atomic absorption spectrometry. For group 2, 40 PAHs were identified in the analyzed tissues. The main sum of total PAH was 202.2.21 ng/g in the liver and 231,10 ng/g in the muscle, being naphthalene, pyrene, phenanthrene and fluorene the most abundant, which indicate the contamination by oil spills. The percentage of alkylated PAHs, which also indicates the presence of oil, was high in both tissues. No difference was observed for PAH concentrations according to the tissues, however, cluster analysis identified two PAHs retention profiles, one pyrogenic and one petrogenic. As for the trace elements, 10 minerals were identified in the different tissues analyzed from the animals belonging to Groups 1 and 2. For both groups, the most abundant elements were Zn, Al, Cu and Ni, however, for group 2, in addition to of the mentioned elements the concentrations of Pb also presented high amounts in relation to the others. The two groups analyzed had higher concentrations in the liver than in the muscle, with Group 1 showing higher concentrations when compared to Group 2. Both groups did not show significant differences between the biometric measurements of the animals and the concentration of substances. The results obtained indicate that sea turtles are major victims of pollution. The high values of PAHs recorded in the specimens suggest the intense contamination of these animals as a result of offshore human activities that involve extraction and transport of oil. In addition, it was observed that part of the profile of PAHs found in sea turtles is similar to the oil from the spill documented in 2019 in the Northeast. The quantified trace elements also suggest high levels of marine pollution, however, an increase in the accumulate of substances in the tissues as a result of the spill was not observed, which may occur due to the short time of exposure of these animals to the residue.