Guanabara Bay is a coastal ecosystem where changes in the drainage basin over the years led to its current condition of environmental degradation. The diagnostic reasons and approaches for differentiating hydrocarbon sources are based on literature data and their application in the environment is difficult to extrapolate. This study aims a critical evaluation of these tools by analyzing two types of contributions, the atmospheric particulate matter (PM2,5) in the Metropolitan Region of Rio de Janeiro and samples of petroleum and their products of Brazilian origin, interpreting the results separately and linking them to data obtained in sediment samples from the same bay. The hydrocarbons concentration in the atmosphere is relatively low, where precipitation proved to be the main atmospheric phenomena to influence the concentration of particulate matter and hydrocarbons. The vehicular emissions, mainly derived from gasoline of vehicles, are the main source of hydrocarbons to the atmosphere. The concentration of hydrocarbons in sediments corroborates the intense chronic contribution which the bay is subject, presenting the anthropogenic source as the main cause of levels detected. Many of the diagnostic reasons and limits established in the literature do not correspond to the values found in different matrices analyzed, there is also overlap between these values. The sediments of Guanabara Bay are in a high state of degradation that interferes with the sources quantification and assessment of contributions. A principal component analysis performed with the PAHs relative proportion in relation to the compounds with the same molecular mass proved to be the most appropriate methodology for evaluating contributions. The polycyclic aromatic hydrocarbons not usually quantified in environmental studies, especially the ones with mass 278 and 276, demonstrated greater ability to discriminate and separate samples geographically regarding the contamination origin.