Hydrogeochemistry of freshwaters crossed by the Transamazon highway, Northern Brazil

Abstract

In the context of the comprehensive study of the hydrogeochemistry and classification of Amazon freshwaters, 80 rivers crossing the E-W transect of the Transamazon highway, between Altamira and Humaitá (Brazil) were analysed (pH, specific conductance, suspended solids, color, alkalinity, Cl, SO4, Na, K, Mg, Ca, Ba, Sr, Al, Fe, Mn, Cu, Si, C org, NH4, and PO4). The chemical data were evaluated and discussed under the following headings: - average content of major and trace elements compared to the world average. - relative dominance of major ions compared to the percentages of sum components of major cations and anions, respectively, - use of MAUCHA diagrams to depict the major ionic environment, - frequency distribution of major and trace elements and their relation to Amazonian and world scales, - variability of major and trace element content along the transect in relation to the geological conditions in the respective watersheds, - comparison of chemical characteristics of groups of waters from geologically different watersheds with their signifìcant differences. The results are fully described and presented in 16 figures and 7 tables