Abstract Mining operations disturb the natural hydrological cycle at a local scale by creating new pathways for water flow and conveying large amounts of water, both for use in ore beneficiation and through the dewatering of mining workings. Sulfide minerals exposed to water and oxygen are oxidized through chemical and microbial-enhanced reactions, significantly altering the quality of water (acid mine drainage). Stable isotopes may reveal important information concerning water origin and transfer, as well as chemical processes and solute fluxes within the aqueous environment. Several case studies illustrate the use of stable isotope techniques for clarifying aspects related to water circulation in mining areas within Romania and Finland. Hydrogen and oxygen stable isotopes coupled with total dissolved solids have been used to characterize mine water and for assessing water sources, flow paths and mixing processes at some Romanian mining sites. At Talvivaara mine in Finland, water isotopes and chemical composition were used to determine the extent of waste water contamination in groundwater systems after a leakage at gypsum ponds.

Abstract Karst science is beginning to recognize and understand better the interaction between conduits and the fractures and/or pore spaces within the aquifer. The relationship has important significance in relation to the understanding of contaminant transport, resource management and dewatering practices. This study presents the results of a dye trace carried out to investigate the link between the aquifer and conduits near a large dewatered quarry in the Mendip Hills in Somerset, England. At the point of undertaking the study, there were no records of the quarry directly intercepting any conduits but water from the conduit(s) is known to be drawn into the quarry. During the study, water from the conduits was observed to be lost to and gained from the fractures in different places in the aquifer. This complexity highlights the dependence of conduit flow on water levels in the aquifer and the sensitivity of groundwater in karstified aquifers to contamination.