Ocorrência de compostos policíclicos aromáticos heterocíclicos contendo enxofre (PASHs) e mercúrio na biota marinha: uma perspectiva químico-ecotoxicológica

Abstract

This study employed polychaetes and corals as tools to determine the occurrence of harmful substances in the environment, such as sulfur-containing Polycyclic Aromatic Heterocycles (PASHs) and the metal mercury (Hg), along the coastal zone of the state of Bahia. For polychaetes, 14 PASH compounds were quantified, with the highest concentrations detected via GC-MS being ∑2,8-DMBT (5,960 ng g⁻¹); ∑4-MDBT (2,160 ng g⁻¹); and ∑3-MBT (1,136 ng g⁻¹). The samples with the highest PASHs and THg concentrations were collected in the Itaparica region. In corals, 8 PASH compounds were detected, with the highest concentrations found for ∑BT (2,790 ng g⁻¹); 2-MBT (2,163 ng g⁻¹); and 2,1-BPT (1,650 ng g⁻¹). To further investigate potential chemical aspects influencing the bioaccumulation of both pollutants in biota, Spearman multivariate correlations were established between the concentrations of these contaminants. For the interpretation of significant correlations, the thiophilicity theory (sulfur affinity) was applied. This theory uses an affinity scale that provides a framework to justify possible positive interactions between the sulfur atom present in the structure of PASHs and the mercury element. In addition to determining the occurrence of PASHs and THg in the environment, an in vivo test was performed with the model organism Artemia franciscana, aiming to expand knowledge on the toxic effects of PASHs in marine organisms. The tests conducted involved toxicity and bioaccumulation in the presence of dibenzothiophene (DBT) and mercury chloride. Results observed for Artemia franciscana showed a 100% increase in mortality in the model organisms under simultaneous exposure to DBT and mercury at equivalent concentrations. Overall, the afore mentioned experiments contribute to broadening the scope of knowledge regarding the occurrence, toxicity, and bioaccumulation of PASHs and Hg in the marine environment and biota, as well as the synergistic toxic effects when dibenzothiophene (DBT) and mercury occur simultaneously in polychaetes and corals.