Towards a better understanding of flow-related processes in the vertically distributed compartments of karst aquifers by combining natural tracers and stable isotopes

Understanding infiltration pathways throughout the different compartments of karst systems (soil-epikarst-unsaturated zone-saturated zone) is vital to assess recharge processes, vulnerability pollution, and general hydrogeological functioning these kind aquifers. To gain deeper insight into soil-water-rock hydrogeochemical processes occurring vertically hierarchized aquifer evaluate applicability soil natural parameters as groundwater flow tracers, present work analyzes spatial temporal evolution total organic carbon -TOC-, intrinsic fluorescence related matter, nitrates, δ13CTDIC, values stable isotopes δ2H δ18O from water molecules at sampling points in a geologically complex south Spain (Jarastepar carbonate massif). Over two years, rain (30 60 cm deep) samples were collected simultaneously an experimental plot along with top saturated zone base-level spring. Results show that variation concentration tracers signal (δ2H δ18O) smooth aquifer, rapid variations unsaturated after events delayed effects zone. At same time, δ13CTDIC nitrate rise subsurface flow. While isotope evidences shorter transit time between areas than subsequent path toward permanent base springs, affected by pollution sources near discharge areas, so its questionable. Finally, matter (TOC fluorescence) mineralizes (or degrades) up 90% first centimeters basal springs. An exponential decreasing trend defines relationship TOC caused attenuation path, while increases because higher residence contact host rock. These results, together previous research based on other (chemical, isotopes, dating tools) dye tracing experiences, permit link range times, hours-days years-decades. Meanwhile, evidence filter function All findings highlight usefulness and, particularly, within