L’impatto del pascolo sulla qualità delle acque carsiche.

Karst aquifers represent some of the main drinking-water resources of the world. The land use activities, often developed within these aquifers, are the cattle grazing and manure spreading. Pasture and manure spreading are able to cause bacterial contamination of drinking water in karst aquifers. The time dependence of microbial contamination is strongly conditioned by the distribution of precipitation versus time, with emphasis on those precipitation which produce effective infiltration and transport of microorganisms from the ground toward both the groundwater and the springs. Both the retardation and the number of microorganisms transported into the subsurface are strongly conditioned by the interaction with soil and aquifer. This interaction often produces significant differences between microorganisms, due to differences in their properties for attachment to solid surface within both media. Significant differences concerning the temporal and spatial distribution of groundwater microbial contamination is expected in the case the system “swallow hole - karst conduits - spring” is partially located within the saturated medium or in the case the same system is entirely located within the unsaturated medium.