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

Different clean-up methods to determine isotopic composition of n-alkanes were tested. Sources of organic matter in Guanabara Bay were re-examined through the δ13C of individual n-alkanes in surface sediment samples. The n-alkanes were efficiently isolated without significant losses of the compounds of interest. The δ13C of n-alkanes (n-C17 to n-C35) ranged between -34.0 and -26.4‰. More depleted δ13C values associated to higher carbon preference index (CPI > 4) suggest prevalence of biogenic n-alkanes from terrestrial origin in the inner stations influenced by inputs from mangrove areas. Small isotopic differences between odd and even-numbered chains and 13C-enrichment in long-chain homologues indicate a petrogenic hydrocarbons contribution. Higher concentrations of short-chain compounds associated to a more 13C-enriched total organic carbon (TOC) were found near the most intense sewage discharges. Results show that δ13C of n-alkanes can be applied to a highly degraded system as the Guanabara Bay and help improve the characterization of the organic matter.

Ethanol is a biofuel produced in Brazil through fermentation of sugarcane, requiring vast plantation areas and water availability. The present work aimed at testing isotopic markers as tools for ethanol source appointment or certification of origin. For this, oxygen and hydrogen isotopic patterns were determined in plant-water, soil-water, rainwater, and water from reservoirs and some rivers in four sugarcane crop areas. The isotopic fingerprint of carbon and hydrogen in ethanol produced in the respective mills was also determined. Samples were collected in 2011 and 2012 in crop areas of the state of Amazonas (North), Mato Grosso (Center-West), São Paulo (Southeast) and Rio Grande do Sul (South). The substantial and complex influence of the hydrological cycle on the ethanol δD and the small δ13C variations constrain the use of isotopes for the intended objectives.

The Marine and Environmental Studies Laboratory at PUC-Rio, in partnership with the PETROBRAS R&D Center (Brazil), conducted an interlaboratory comparison of aliphatic and aromatic hydrocarbons and trace element determinations. The goal of this study was to produce a homogeneous and stable material and obtain consensus concentration values for its use as a reference material (RM) for sediments from tropical regions. The prepared material is adequate for use as a reference material because it has remained stable (Test F, ANOVA, p < 0.05) since its preparation in 2007. In this study, several alkylated polycyclic aromatic hydrocarbon (PAH) compounds were included, and the resulting dispersion was the same order of magnitude as the parental PAH (16 PAH USEPA).

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.