The Guanabara Bay serves as the estuary to 90 rivers and canals, it is considered an eutrophic environment with intense primary productivity and considerable amount of nutrients, mainly coming from the river drainage and sewage dump and owns the second largest industrial complex of Brazil. Because of these aspects, the purpose of this paper is to characterize the biogeochemical aspects of Guanabara Bay on tidal cycles, analyzing the flow of nutrients dissolved inorganic and hydrocarbons in SPM. In addition of that, characterize the source of particulate organic matter through the use of tools such as elemental composition (C and N) and isotopic delta 13C and delta 15N. For this, the samples were collected in the dry and wet seasons in a fixed point near by the entrance of Guanabara Bay. The samples were collected over complete tidal cycle being 13 samples (surface, middle and bottom) totaling 39 sampling. Speed and direction of currents, salinity and water temperature data were obtained with an ADCP and CTD. The methodology consisted of field analysis (T celsius, pH and DO measures) and laboratory. In the lab, were used colorimetric and Spectrophotometric methods for nutrients NH4 more, NO2 less, NO3 less and Pinorg) POC, TOC, DOC, PON, SPM and chlorophylls assays. The extraction of hydrocarbons was held in the Soxhlet apparatus (EPA 3540C), clean-up column and analyzed in GC-FID (aliphatic). The isotopic and elemental composition analyses were made using dry combustion and MS, respectively. The results demonstrated that T celsius degrees and pH varied little throughout the water column in C1, but for C2 a sharper variation occurred for Tcelsius. DO, NH4 more, NO3 less and Chl-b were higher for the C1. The Salinidade, SPM, Pinorg, bacterioplakcton, delta 13C, delta 15N and TAH were higher for the C2. The majority of compounds obtained higher concentrations in events of ebb tide. The aliphatic hydrocarbons were originated, predominantly, of oil degradation by microorganisms, primarily for the C2. For the C1, n-alkanes occurred mixed with predominance of terrestrial biogenic and petrogenic origin. The natural tracers C/N ratio, delta 13C and delta 15N isotope used to identify the major sources of OM evidenced a dominance of marine source of MO for both campaigns. Dissolved inorganic nutrients flow were on average in the order of 104 for nitrogenous and aliphatic hydrocarbons in SPM and 102 for the inorganic phosphorus daily being exported from GB. Besides, GB exports a large amount of material as chlorophylls, POC and PN. The COD presented positive flow for GB, however we must take into consideration the sampling point receives a strong influence of the outfall of Icaraí sewage and other sewages near the mouth. The use of statistical tools helped to proof the significant difference between the campaigns, it could help to validated the choice of seasonality criteria. Cluster analysis and PCA demonstrated an association between parameters analyzed.