Amazon, the studied area in this work presents many relevant characteristics, so that it requires more detailed inquiries about molecular markers composition in its environment. Despite of great importance of its biodiversity and freshwater reservoirs, the Amazon basin has been suffering with reduction of its green area due to forest fires and deforestation. In the Amazon basin, the river Solimões has an important role for navigation, because it is the only way to get to some cities. Besides, it is the major transportation route for the oil industry settled in that region. For these reasons it is understood the utter importance to perform characterization of molecular markers for inferring different composition origins in sediment. This work was carried out inside of the studied area of PIATAM III Project (Potential Impacts and Environmental Risks of the Industria of the Oil and Gas in Amazon), a relevant multidisciplinary project of Petrobras. The PIATAM acts along 400 km of the river Solimões, between the cities Coari (S03 39 , W63 33) and Manaus (S03 05 , W60 03). Superficial sediment sampling were conducted during flood (June 2005, Sampling I) and dry seasons (November 2005, Sampling II). During Sampling II, it was also sampled sediment profiles in three lakes. Superficial sediment samples from industrial area of Manaus were analyzed for results comparison. In these sediments, analyses were carried for saturated and aromatic hydrocarbons, and trace metals. Beside these parameters, the following complementary data were also analyzed: organic carbon, grain size, pH, Eh and 210Pb dating for the sediment profiles. Extractions for organic compounds were performed by Soxhlet (EPA3540C), cleanup by liquid chromatographic (EPA 3510). Sediment extracts were analyzed by GC-FID (saturated hydrocarbons) (EPA3630), GC-MS (PAHs and biomarkers) (EPA-8270D) and CG-ECD (organochlorides) (modified UNEP71). Trace metal analyses were performed by ICP-MS and ICP-OES. Results of this work have shown that sediments from Coari- Manaus stretch presented great variability for levels of organic pollutants. However, they were below of reference levels established by environmental agencies. Concentrations varied from 0.82 to 148 ug g-1 for saturated hydrocarbons and from 52 to 774 ng g-1 for total polycyclic aromatic hydrocarbons (PAH). For metals, Cd presented the lowest concentrations and a maximum value of 1.33 (mi)g g(-1). Zn was the element with the highest intensity with a maximum value of 147.3 (mi)g g(-1). Among organochlorine pesticides, results only for pp DDE and pp DDD were found at trace levels. The concentrations obtained in the industrial area were in all cases the highest ones, indicating a contaminated environment. Sediments from the Coari-Manaus stretch, presented hydrocarbons mainly from biogenic sources. The compound identification from biogenic precursors (a-amyrin, b-amyrin e lupeol) was performed by analyses of biomarkers. The calculation of diagnostic indexes, the statistical analyses (PCA, Spearman) and the investigation of biomarkers have confirmed that part of the input by biogenic sources is a consequence of biomass combustion contribution due to fires in the Amazon area. Some sediment core results revealed not only the evolution trend for sources of biomass combustion, but also the characteristics of recent diagenetic processes.