Surface and subsurface environmental degradation in the karst of Apulia (southern Italy)

Karst environments are highly vulnerable to a variety of degradation and pollution problems. Geology (fractured carbonate rocks), morphology (presence of a network of cavities produced by karst processes), and hydrogeology (rapid concentrated flow through fractures and conduits) of karst carbonates strongly favour the movement of contaminants towards the water table. In particular, poor quality of subsurface water can derive from polluting substances flowing at the surface, and/or by direct immission of liquid and solid waste into the water table through the systems of conduits and joints in the rock mass. As a consequence, water quality can deteriorate severely, which implies very high economic and social costs in order to clean the polluted sites and restore the original situation. In some cases, such as when the original karst morphology is changed because of anthropogenic interventions, the variations created in the landscape are not recoverable, and a loss of sites of naturalistic interest has to be registered. High vulnerability of a typical karst region of the Mediterranean area is illustrated in this paper by describing some case studies from Apulia, southern Italy. The Apulia region, where karst processes have had a prominent role in the development of the present landscape, is mostly underlain by intensely karstified limestone. Two cases of pollution due to solid waste into karst cavities (Grave di S. Leonardo in the Gargano Promontory and Grave Pelosello in the Murge plateau), landscape transformation in the Minervino Murge area, and degradation of Gravina Monsignore, a typical karst valley in southeastern Murge, are described in the paper. In two out of four cases, degradation of the sites was discovered thanks to activity from local speleologists, who also acted as promoters for cleaning and safeguarding the polluted sites. These examples underline well the mismanagement of karst territories (in particular, the common practice to dump refuse into sinkholes and caves), the pollution of limestone aquifers, and the effects that such pollution in karst areas might have in terms of the risk to public health.