Physical chemical characteristics of lake titicaca and lake poopo bolivia
Rivista di Idrobiologia 24(3): 87-140
A strategy for investigating the system of lakes and rivers in the Andean highlands is presented. In order to study this system we are using a strategy made up by three stages : global, analytical and statistical. The Institute for Chemical Research of the Faculty of Natural Sciences in the University San Andres in La Paz (UMSA) and the French organization for investigation in overseas countries (ORSTOM) have been conducting since 1976 a series of investigations, according to the previously mentioned schedule. The present extension of Lake Titicaca is the results of the quaternary tectonic evolution of this zone. The characterization of volcanic flows, ancient lacustrine levels, moraines and pediments are important indications in the determination of the extensive quaternary deformations responsible for the creation of the lake Titicaca fossa. Poopo lake can be considered a lake having a mixed origin : tectonic and due to the action of a river. Lake Titicaca, ellipsoidal in shape, is the 21st largest lake in the world. Lake Poopo is elliptical. The climate in the basin of Altiplano is cold and semiarid. The main fluvial input is due to rivers coming from volcanic and sedimentary formations with high salinities (5 to 20 mM/l) and bicarbonate-sulfate-chlorine facies, the rest is due to rivers crystalline formation with low salinities (5 mM/l) and a bicarbonate calcio-sodic facies. The annual salt turn-overs vary from 0.20 to 0.50% according to the major elements. Consequently, the time fluctuations of the hydrochemistry of the lake are very weak. Of the fluvial waters that reach the Poopo 92.5%, come from the Desaguadero River, and 7.5% from the Marquez River. The water contribution from other rivers is not very significant. As the salt reserves of the Poopo lake are weak, the annual renewal of the dissolved elements is high especially in certain areas of the lake, so the time of renewal of Na+ and Cl- is 26.5 years and one week for silica.