Isotopic hydrology in the Amazonia: 2. Relative discharges of the Negro and Solimões rivers through 18O concentrations

Abstract
Measurements of 18O were made on samples of water collected during a 2‐year period on the Amazon below the confluence of the Negro and Solimões rivers. The measurements show that the Amazon is not completely mixed 120 km below the confluence. Estimates of relative flows were based on the 18O concentrations and show that the relative contribution of the Negro varied from 19% in February 1973 to 68% in July 1973.