“Using Radon as a Naturally Occurring Tracer in the Bussento river karst systems (National Park of the Cilento, Vallo di Diano and Alburni, - European and Global Geopark, Southern Italy)”

Karst aquifers provide 25% of the overall drinking water resources to the world‟s population and sustain aquatic life in most fluvial systems, providing several ecological services to human beings, although, because of their complex links between surface and groundwater, turn out to be very vulnerable to contamination and pollution. This paper describes the preliminary findings from Radon-222 activity concentration measurement data collected in streamflow and instream springs during monthly field campaigns in a typical Mediterranean karst river: the Bussento river (Campania region, Southern Italy). The general aim is to investigate the complex interactions and exchanges between streamflow and groundwater, at scales that are imperceptible to standard hydrological and hydraulic analyses. Experimental data about 222Rn activity concentrations in streamflow and inflow spring waters, from selected sampling stations, have been acquired and managed by means of the Radon-in-Air analyzer, RAD7, together with the Radon-in-water accessories, Radon Water Probe and RADH2O (DURRIDGE Co. Inc.), for continuous and batch sampling measurements, respectively. In addition, data about physical-chemical and streamflow rate have been, also, collected in-situ. During preliminary surveys, appropriate sampling procedures and measurement protocols have been tested, taking into account the different local hydrogeological and hydrological situations occurring along the Bussento river basin