Sensonal variation in the major cation (Na,K,Mg and Ca) content of the water of Lago Camaleao, am Amazonian floodplain- lake near Manaus, Brazil

Abstract

Changes in the major cation content (Na, K, Mg and Ca) of the Lago Camaleão, one of the várzea lakes'on an island in the Rio Solimoes/Amazonas near Manaus were foliowed during one year. Comparative changes were also followed in the Rio Solimóes. Changes in the electrolyte content of the lake water, presented as total maior cation content, are extremely geat dpriq the wriod of investigation. Nov. 1980 to Nov. 1981, and show a pronounced annual periodicity. During the low water period (Oct. 1981) the ion concentration reached its maximum and was more than 15 times higlier than in the river at the same time. With rising water level, in flow of comparatively electrolyte poor water from the river and simultaneously increasing rain fall dilute the water in the lake. In the foiiowing months there is a relatively sudden reduction of the electrolyte wntent of the lake water.