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Eastern coast of the Adriatic Sea consists of karstified carbonates. It belongs to the well-known Dinaric karst region. The coast is extremely indented and there are 718 islands with numerous rock crags and reefs. Some of the inhabited islands use their own water resources for public water supply, or plan to do it in the future. Since karst rocks are extremely permeable, the seawater intrudes into underground water resources, thereby forming the wedge. A wide transition zone occurs between this seawater wedge and fresh water aquifers. Consequently, island groundwater reserves turn brackish to a certain extent. In this study, 77 water samples were collected from a wide variety of water resources. Comprehensive statistical and mathematical multivariate analysis of these data was performed. Simple statistical approach showed several useful correlations among some parameters, and more complex multivariate techniques extracted three factors in connection with three natural processes: (1) mixing with the seawater, (2) carbonate dissolution and (3) human influence (pollution) and nitrogen transformation processes. The results of this study demonstrate that in situ measurement of electrical conductivity is adequate for the very rough field estimation of numerous parameters.

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A quarter of the world's population uses groundwater from karst aquifers. A range of emerging organic contaminants (EOCs) are considered a potential threat to water resources and dependant ecosystems, and karst aquifers are the most vulnerable groundwater systems to anthropogenic pollution. This paper provides the first global compilation (based on 50 studies) of EOCs in karst aquifers and explores EOC occurrence and the use of EOCs to understand karst systems. Of the 144 compounds detected in the reviewed studies, the vast majority in karst groundwater are pharmaceuticals and pesticides. Maximum concentrations of compounds varied over five orders of magnitude, and nearly half of the detected compounds exceed 100 ng/L. Karst groundwater is shown to have lower frequency of detection and lower concentrations compared to surface waters and local shallow intergranular aquifers, but overall higher concentrations compared to other major aquifer types. A growing number of studies have demonstrated the utility of EOCs and some legacy compounds for groundwater quality assessment and as tracers for characterising karst systems. They can improve understanding of vulnerability, storage, attenuation mechanisms, and in some cases have been used to assist with catchment delineation. This is a growing research area for karst hydrogeology, and more research is needed to understand EOC contamination of karst aquifers, and to develop EOCs as tracers within karst to improve our understanding of this critical water resource.

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