CONICET | Buscador de Institutos y Recursos Humanos

In the region of the Stepanek rock glacier (69°19′/69°26′ W and 32°55′/32°59′ S), Mendoza, Argentina continuous hydrochemical monitoring is being carried out. The aim is to analyze underground and superficial waters tha interact with the cryoform. The cryogenic basin of the study area where the hydrological flows originate is 11.4 km2 and is interrupted by the mentioned cryoform, as in other cases of the dry and central Andes. This cryoform is a rock glacier of glacigenic origin. The water proceeds from the melting of perennial and temporary snow patches and from the melting of the active layer, which is frozen in winter. This situation applies not only to this rock glacier but also to the entireupper basin of the valley. The active layer is partly saturated with winter precipitation related to storms from the Atlantic as well as from the Pacific Ocean. Supposedly, and according to the analysis of the isotopic enrichment of a sample of 2013, superficial water or groundwater is becoming a water supply from the intrapermafrost of the cryoform, because of degrading and melting permafrost. This process may be supported by the scenery of the global warming or climatic variability. Hydrogeochemical research allows the interpretation of different water flows, which cross the rock glacier through its active layer. This water flow is suprapermafrost water, but it is supposed that other flows may take a subpermafrost path. Two different monitoring sites, Van06 (3479 m a.s.l.) and Vmn07 (front of the cryoform, 3338 m a.s.l.), 800 m apart, show interesting anomalies with a decrease in temperature of 2.4°C, parallel to the decrease in altitude, but a rise in pH from 2 to 3 units. In the same way there is a notable reduction in the concentration of some heavy metals, which are first detected at Van06. These may be considered health-threatening, such as Cd (2013?15 average = 0.023 ± 0.002 mg L?1), Zn2+ (2013?15 average = 4.2 ± 0.4 mg L?1) and Ni (2013?15 average = 0.928 ± 0.093 mg L?1). This anomaly allows us to infer retention of chemical elements in the internal structure of the rock glacier. The concentration of Si, measured in Van07, also shows a decrease in superficial water and that supports the idea that Si may also be retained in the internal structure of the cryoform. This last topic was also remarked before by Trombotto.