Resumo (Abstract) do trabalho em Inglês: Several works use water biogeochemistry as a tool in the study of hydrographic basins, relating it to geology, vegetation cover, hydrology, etc. This work intends to carry out a biogeochemical characterization of river waters at different sampling points within the domains of the Descobrimento National Park (DNP). The disorder in the use and occupation of the land in the region caused negative environmental impacts in the watersheds of the extreme south region. The historical changes in land use that occurred in the region were responsible for the alteration of one of the main Brazilian biomes, the Atlantic Forest, and justify the realization of this work. The general objective of the study is to evaluate the chemical composition of river waters from microbasins of the Descobrimento National Park (DNP), identifying the sources of chemical elements and the influences of the buffer zone on river waters. For this, surface water samples will be collected, in the central portion at different points in the rivers Japara (JP01, JP02, JP03), Cahy (RC), Rio do Sul (RS) and Lagoa só não vou (LSNV). In the field, the physicochemical parameters (pH, electrical conductivity, temperature, redox potential, O.D. concentration, O.D. saturation) will be evaluated. In the laboratory will be determined the alkalinity, the concentration of supended particulate matter (SPM) chlorophyll a, phaeopigments and the concentrations of and NO2-, NO3-, NH4, PO4-3, SiO2, The data obtained will be worked statistically through an analysis of similarity and principal component analysis (PCA). It is expected that after monitoring the watercourses in the microbasins, it will be possible to identify the biogeochemical characteristics of the river waters, and that the results will indicate the quality of the waters at the analyzed points, if they are within the established parameters.