Geochemistry of the Madeira River, Brazil: comparison of seasonal weathering reactions using a mass balance approach

ittle information is available regarding the geochemical factors and reactions controlling the seasonal variation in major elemental distribution in river waters. In this note, we have utilized previously published seasonal water chemistry of the Madeira River, Brazil (Pessenda et al., 1986) and the geochemical model NETPATH to determine the different chemical reactions controlling major solute distribution in the river on a seasonal basis. Our modeling effort suggests that there are major seasonal differences in the weathering reactions in the Madeira Basin. This is, in part, due to seasonal variations in ∑CO2 input into the river.