Polycyclic aromatic hydrocarbons in sediments of the Doce River estuary and the adjacent marine area: advances using fuzzy logic
Name: DANILLO SILVA ZACCHÉ
Publication date: 26/02/2026
Examining board:
Name |
Role |
|---|---|
| CESAR ALEXANDRO DA SILVA | Coorientador |
| LUANA SANTOS MOREIRA | Examinador Interno |
| LUIZ AUGUSTO DOS SANTOS MADUREIRA | Examinador Externo |
| MARCELO DA ROSA ALEXANDRE | Examinador Externo |
| PAULO ROBERTO FILGUEIRAS | Examinador Interno |
Pages
Summary: This study examines the application of fuzzy logic–based tools for the environmental monitoring of polycyclic aromatic hydrocarbons (PAHs) in sediments, highlighting their ability to address uncertainty and support gradual interpretations. Three main approaches were employed: fuzzy clustering, fuzzy synthetic evaluation, and fuzzy inference systems. Initially, fuzzy clustering was applied to identify the extent of contributions from the main PAH sources in sediments from the marine region adjacent to the mouth of the Doce River (Linhares, ES, Brazil), using samples collected between the summer of 2010 and the winter of 2011. This technique enabled the assessment of the relative importance of pollutant sources to the overall PAH pool, revealing clear seasonal variations. PAHs derived from biomass burning predominated during the summer, whereas compounds associated with fossil fuel combustion were more prevalent in the winter. Subsequently, fuzzy synthetic evaluation was employed to evaluate the ecological risk of PAHs in sediments from the Doce River estuary, considering periods before (2015) and after (2016) the impact of mine tailings released following the Fundão dam failure in Mariana, MG, Brazil. This approach allowed a gradual assessment of changes in sediment quality resulting from the disaster. It was observed that some compounds shifted from low to moderate ecological risk following the arrival of the tailings. Despite a significant increase in PAH concentrations after the event, the integrated analysis indicated that the overall risk of adverse effects associated with these compounds remained low. Finally, a new sediment quality index based on fuzzy logic was proposed, using a Mamdani-type fuzzy inference system. The aim was to integrate different sediment quality guidelines into a single, clearer, more robust, and reliable indicator. The application of this index to data from both the estuary and the adjacent marine region demonstrated that it reproduces the conclusions obtained from the other evaluated methodologies, but in a simpler, more objective, and comprehensive manner, taking into account priority PAHs. Overall, the study highlights the potential of fuzzy logic as an effective tool for environmental assessment.
