The Manso Glacier drainage system in the northern Patagonian Andes: An overview of its main hydrological characteristics

PASQUINI, A.I., LECOMTE, K.L., DEPETRIS, P.J.

HYDROLOGICAL PROCESSES

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2013 vol. 27 p. 217 - 224

0885-6087

The Manso Glacier (~41ºS, 72ºW), in the northern Patagonian Andes of Argentina is a regenerated glacier that, like many other glaciers in the region and elsewhere, has been showing a significant retreat. The hydrological trend analysis of the riverine and lake systems, partially fed by the Manso?s melt water, shows in the uppermost reaches a monthly and annual decreasing trend in lake levels and river discharge, which are connected with decreasing precipitation and, also, with decreasing melt water discharge. Downstream, the decreasing signal looses statistical significance, at first, and then reverses the trend and clearly becomes significantly positive suggesting that, on its way to its Pacific outfall, the Manso River receives abundant Andean melt water. The system is seemingly influenced by ENSO occurrences which, during El Niño events, supplies larger-than-usual snow and rain fall. The system?s oligotrophic nature (nitrogen is the main element limiting biological productivity) is evident in proglacial Lake Mascardi, which is a typical monomictic lake that is also showing a statistically significant water level decrease. The Manso?s drainage basin hydrochemistry is controlled by a weathering-limited regime that supplies limited solutes, mainly from the hydrolysis of plagioclase and other silicates, and pyrite oxidation which in turn, determines a significant concentration of SO42- in the system?s uppermost stretches. The concentration comparison of dissolved major, minor and trace elements in river waters, with the nearly pristine glacial melt water suggest the occurrence of diverse geochemical processes (e.g., adsorption, biological consumption) that control the system?s hydrochemistry.