The present work aimed at evaluating indicators of hydrocarbon sources to sediments from the Solimões River region, in the central Amazon. The 16PAH, the alkylated homologs and molecular markers were investigated. The entire series of alkylated PAH were present and, in some cases, with a distribution observed when oil residues dominate. Nevertheless, hopanes characterizing immature environments undergoing diagenetic transformation were identified in samples from the Solimões River and in surface as well as in core sediment samples from Preto Lake, in the Coari-Manaus stretch. Investigation suggests early diagenesis of the organic matter confirmed by identifying biogenic markers produced during organic matter transformation. Some of these markers derive from incomplete combustion of biomass and are contained in particulate matter formed during forest burning. In the sediments of an industrial area near the city of Manaus, the entire series of mature hopanes was present indicating anthropogenic source of hydrocarbons. The results so far obtained point out the complexity of PAH source appraisal. region Amazon 16PAH investigated cases dominate Nevertheless Lake CoariManaus Coari Manaus stretch burning hydrocarbons appraisal

O histórico de acumulação em sedimentos de produtos de combustão produzidos na área metropolitana ao redor da Baía de Guanabara foi avaliado através de black carbon (BC) e hidrocarbonetos policíclicos aromáticos (HPA) como indicadores. A concentração de BC variou de 0,23-0,51%, com uma tendência crescente de acúmulo de massa ao longo dos últimos 118 anos, mas a proporção BC/carbono orgânico caiu nos últimos 30 anos, possivelmete reflexo de eutrofização. Observaram-se as maiores concentrações de HPAs pirolíticos nos períodos entre 1925 e 1976, condizendo com o período subsequente de desmatamento, urbanização e industrialização que ocorreu na bacia da Guanabara. Estes HPAs foram melhor caracterizados pelo índice diagnóstico BFl/(BFl+BePy). Os dados obtidos permitiram caracterizar os principais eventos que influenciaram o padrão dos produtos de combustão: queima de biomassa e de derivados de petróleo, a crise econômica nos anos 1970 e 1990 e a entrada de etanol na matriz energética brasileira.

The accumulation history of combustion products from the metropolitan area around Guanabara Bay was evaluated using black carbon and polycyclic aromatic hydrocarbons as indicators. BC concentration varied between 0.23 and 0.51%, with an increasing mass accumulation tendency over the last 118 years, whereas a decrease in the values of the ratio BC/organic carbon was observed in the upper sediment layers, probably reflecting the enhancement of bay's eutrophication process in the last 30 years. Higher concentrations of pyrolytic PAH were observed between 1925 and 1976, being consistent with the subsequent deforestation, urbanization, and industrialization that occurred in the Guanabara basin in the period. These PAHs were best characterized by the BFl/(BFl+BePy) diagnostic ratio. The data obtained allowed the characterization of the main events that influenced the combustion patterns in the region: burning of biomass and fossil fuel, economic crisis of 1970 and 1990 and the introduction of ethanol in the Brazilian energetic matrix.