<p>The karst area in general has very specific characteristics, such as a thin layer of soil on the surface and a very uneven distribution, as well as a multitude of interconnected cracks that enable rapid infiltration of water underground. Because of this, groundwater in weathered carbonate rocks requires a very precise approach in management and protection. In the Republic of Croatia, almost half of the country’s territory is built of karstified carbonate rocks, in which there are significant amounts of water supplies. In addition, karst aquifers show a high degree of vulnerability to pollution from any human activity that threatens them. For this reason, it is important to carry out a complex analysis of the natural features of the aquifer system and its reaction to anthropogenic action, in order to determine the level of natural protection that the aquifer has. This is exactly what is shown in detail through the analysis of intrinsic vulnerability, which has become an indispensable tool in the research of karst water resources. Old abandoned industrial waste landfills represent problematic sites of potential hazard for groundwater as well as surface water contamination. There are several such locations in the karst area of the Republic of Croatia, three of them are presented in this paper: location Štrmac, Plomin in Istria peninsula, Plaški in Lika region and Jadral in North Dalmatia. The purpose of this work is to assess the levels of groundwater intrinsic vulnerability with the mobility of certain potentially toxic elements in soils formed at industrial waste disposal sites. By combining geochemical modelling and groundwater vulnerability assessment, an attempt was made to understand the movement of contaminants and their chemical behaviour in different environmental conditions. This helps in predicting whether certain metals might leach into the groundwater and in what form they are likely to be present, which has direct implications for water quality and human health.</p>