Diagnóstico da contribuição de fontes de poluição na costa de Fortaleza usando marcadores moleculares de petróleo e cromatografia bidimensional abrangente

Abstract

The study of the harbor zones is important for its economic representation and for being the place of entry of harmful chemicals to coastal ecosystems. The aim of this study is to determine the levels of molecular markers in sedimentary samples, investigating their composition and making them different from natural and anthropogenic sources, and to estimate the ecological risk caused by these compounds along the coastal area of Fortaleza-CE. With the GC techniques was possible to determine the main groups molecular markers: PAHs (parent and alkylated); n-alkanes, isoprenoids (pristane and phytane) and petroleum biomarkers (hopanes and steranes). The n-alkanes/isoprenoids, petroleum biomarkers and polycyclic aromatic hydrocarbons (PAHs) levels were quantified in all samples of surface sediments using GC-MS. GC-FID, GC × GC-FID, GC × GC-TOF/MS were used in the qualitative analysis of samples as well as the unresolved complex mixture (UCM). The surrogate standard recovery (deuterated PAHs and triacontane d62) ranged from 64,43% to 126,29%, respectively. The highest levels of contamination by oil and derivatives were observed near from Mucuripe Harbor and neighborhood points that receive direct input from the Ceará and Cocó River. Pyrolytic sources were confirmed by the determination of PAH (5-6 rings) in sediment samples, corroborated by multivariate analysis (PCA). The sums of PAHs levels, petroleum biomarkers, n-alkanes and isoprenoids ranged from 34,88 to 68333,54 ng.g-1; 43,65 to 782723,92 ng.g-1; 1141,39-287642,37 ng.g-1, respectively. The detection of the PAH (4- 6 rings) in the sediment samples suggests contribution from biomass burning, coal and crude oil. The presence of n-alkanes, biomarkers and UCM indicated strong correlation in the hydrocarbon sources associated with petrogenic / pyrolytic in the study area, suggesting multiple sources. Through analysis by GCxGC detects the presence of more than 1000 chromatographic peaks in the UCM. The ecological risk assessment showed that the levels of dibenzo [a] anthracene identified were considered showed a high potential ecological risk to environment, according to national standards (CONAMA) and international (NOAA and CCME).