Groundwater quality in selected caves in Ravni kotari (Croatia)

Complex mechanisms of pollution transport in karst underground and the fact that contaminated cave water can be a health hazard if used for human consumption, imposes the need for monitoring the cave water quality. In order to determine groundwater quality, water samples were collected in four caves in Ravni kotari (Croatia) and analyzed for microbiological and chemical indicators of pollution. Microbiological analyses showed increased concentration of various coliform bacteria at all four locations. Probable sources of pollution are inadequately built septic tanks in nearby villages and bat guano in caves with bat colonies. Chemical analyses indicated values of possible pollutants to be much lower than the permitted values, which reflects the fact that agriculture, as a frequent source of chemical pollution in rural regions, is not as developed as it used to be, thus posing no serious threat to the groundwater quality.