Fluxo de matéria iônica dissolvida nos rios da Amazônia brasileira: uma análise a partir da base de dados do observatório Ore-Hybam

Abstract

The Amazon Basin is the largest drainage basin in the world, occupying a total area of 6.110.000 km2. Its main watercourse is the River Amazon featuring sediment contribution of Andean origin, lot of tributaries, channels under the influence of the hydrologic regimes of flood, full, ebb and dry. Such aquatic environments present unique characteristics regarding the presence of dissolved constituents, these being influenced by dimension and flow of rivers. The dissolved constituents, transported by rivers, stems from the action of rainwater by runoff, and groundwater interaction with soils and rocks. Its chemical composition is the result of dissolution and chemical reactions between solids, liquids and gases, with which the water comes into contact during the hydrological cycle, and may be altered by land use. With the goal of studying the flow balance of matter dissolved ion, specifically ions: Ca2+, Mg2+, Na+, K+, HCO3-, SO42-, Cl- and Si carried by the Amazon basin, this study used the base database of the Ore-Hybam Program (geodynamic controls, hydrological and biogeochemical of erosion/alteration and transfer of materials in the Amazon basin). This program is designed to provide the scientific community trusted data of seasonal variations of water flows and sedimentary geochemistry of the Amazon Basin. The data used for this study were of historical series from 1995 to 2010 in nine collection stations distributed by the Amazon basin, in the rivers Negro, Branco, Solimões/Amazonas, Purus, Madeira and Tapajos. The gathering of this data has given rise to a new basis called definitive basis. Definitive base if calculated the amount of data, average, peak, and minimum concentration, standard deviation and coefficient of inter-annual variation quotas, and monthly flows and ions, with the aid of the Excel Program. Also tried these data for statistical analysis with the aid of the Software Action 2.3, these being, Cluster to observe similar behavior for data collation and Pearson to show correlations between the Ionic composition. It has been estimated the flow of ions in the stations where the interannual and monthly averages, observing the phases of the hydrological cycle, with the descending stream (HCO3-> Ca2+> Si > SO42-> Na+> Cl-> Mg2+> K+). From the calculation of the stream, it has been estimated the flow balance, using equation of mass balance (+ QSa QSb + ... + QSn + Σ = QSx series), monthly and year-to-year in MN + FVA + M (SR + CC) = OB, observing that the Solimões River is the main contributor of ion dissolved matter stream to Óbidos and of its tributaries, the river Madeira is the main contributor