Major and minor elements contribution to discriminate between karst drainage watersheds and to outline underground hydrological connections. An example from Sohodol Valley (Vâlcan Mountains, Romania)
Abstract: Water samples for chemical analyses have been collected from impenetrable karst springs and from water flows intercepted by caves within the area of Sohodol valley. The analyzed inorganic constituents were noticed to belong to two distinct categories. One category included solutes of variable concentrations, likely related to local allochtonous inputs (Al, NO3) and to local occurrences of decaying organic matter (PO4, NO3), such solutes being hence irrelevant in terms of regional patterns of rock weathering. The other category of solutes (Ca, Mg, Na, K, Sr, Ba, Rb, Fe, HCO3 and SiO2) proved to have concentrations that did not differ between two interconnected water flows (e.g., impenetrable karst springs that discharged from a common water body; a cave stream connected to an impenetrable karst spring). Accordingly, the concentrations of this second group of constituents represented reliable chemical fingerprints of a particular karst watershed. And implicitly, water flows having contrasting concentrations of such solutes were conjectured to belong to distinct karst watersheds, which likely differed in terms of chemical composition of the karstifiable rocks, and/or of the impervious rocks which provided allochtonous recharge to the concerned karst drainage systems.