Control on the Evolution of Karst System Solution and Speleothem Geochemistry in the southern Austrian Alps: a palaeoclimatic investigation

Scientific interest in speleothems as recorders of palaeoclimate has increased in recent years due to the proven occurrence of global warming. The aim of this project is to refine current knowledge of environmental change in the Alps over the last few hundred years via work at a particularly well suited site, the Obir Cave in the southern part of the Austrian Alps. In order to interpret the chemical record preserved by speleothems at this active karstic site, it will first be necessary to investigate the current controls upon karst water chemistry. Since the karst system can be divided into the three interacting zones of the atmosphere, soil zone and carbonate aquifer, an extensive monitoring program will be performed in order to monitor seasonal changes in both surface and subsurface conditions on a monthly time-scale, over a period of at least one and a half years. The field data collection protocol will facilitate an assessment of the main processes responsible for the modification of the geochemical signal of rainwater via transit through soil and aquifer zones. The interpretation of field observations and measurements coupled with laboratory data will culminate in the development of hydrogeochemical models detailing the range of controls on karst water chemistry which are transmitted to the speleothem record in the Obir karstic system. The findings of this modelling will then be implemented in the assessment of variations in elemental and stable isotopic compositions in speleothems from the site in order to interpret changes in past environmental conditions.