Abstract
High mountain areas are experiencing rapid hydrological shifts, due to a decline of meltwater sources and a concomitant increase of solute concentrations in freshwater ecosystems. While research on water quality is increasing on river systems influenced by glaciers and rock glaciers, very limited knowledge exists on those influenced by other landforms such as moraines and talus slopes. During late summer 2021, we investigated the chemistry and δ18O in the water of 80 high-elevation springs in 6 massifs of the Central-Eastern European Alps. These springs were sourced either by glaciers, young moraines, rock glaciers, talus slopes, or reference slopes mantled with soil. End-member mixing models revealed a large fraction of (snow or glacier) meltwater at all springs (> 60%), even though rainwater had a higher contribution (up to 40%) at lower elevations. Lithology and the likelihood of ice influence, an indicator that we built using the spring water temperature and the Alpine permafrost map, were the most important predictors of water chemistry in regression tree analyses. Springs draining catchments dominated by paragneisses and/or micaschists had high concentrations of sulphate, nickel, manganese, and other metals. In these geochemical hotspots, all glacier springs, 70% of rock glacier and young moraine springs, 60% of talus slope springs, and 25% of reference slope springs had poor water quality (European Union standards for drinking water). In areas with other lithologies, only 13% of springs exhibited poor water quality. For the springs on paragneisses and/or micaschists, the permafrost presence and the motion of different landform types may enhance nickel concentrations due to acid rock drainage. Finally, we discuss the importance of our findings for water management and freshwater ecosystems.