The investigated area, located in the inner part of the Marche region (central Italy) and belonging to the carbonate Umbria-Marche ridges in the central Apennines, is characterised by very complex geo-structural settings and widespread karst phenomena. Hence, the definition of the relation among the aquifers basing only on the hydrogeological survey is very difficult. The presence of different flowpaths (supposed from the observation of the springs hydrograph) and of hydraulic contact among the aquifers is proved using tracer tests. In particular, the Calcare Massiccio and the Maiolica aquifers are connected under certain tectonic conditions. A new tracer given by a single stranded DNA molecule and a traditional fluorescent dye have been injected into the Montelago sinkhole in different periods (from the recharge to the discharge of the karst system) and recovered in several points along the expected hydrogeological basin, using either manual and automatic sampling and fluorescent traps positioned in creeks, rivers and springs. The DNA molecule is useful to trace surface water and groundwater, is detectable even at very low concentrations, no significant change in water density and viscosity can be observed and its use is not dangerous for the environment (Aquilanti et al. 2013; Sabir et al. 1999). However, DNA is insoluble in groundwater and acts as a particle/colloidal tracer, so it shows a breakthrough curve characterised by higher or lower pulses. The results stress the suitability of DNA as hydrogeological tracer, capable to identify connections among aquifers and study different flowpaths even in high flow conditions when traditional tracers are more and more diluted and often under the instrument detection limit. What is more, Fluorescein tracer allowed for the transport parameter determination, giving mean velocities ranging from 100 to 3000 m/day and mean residence time from some tens to hundreds of hours

THE CONTRIBUTION OF DNA AND FLUORESCENT TRACER FOR THE IDENTIFICATION OF CONNECTIONS IN KARST AND FISSURED AQUIFERS

TAZIOLI, ALBERTO;AQUILANTI, Lucia;CLEMENTI, Francesca;MARCELLINI, MIRCO;NANNI, TORQUATO;PALPACELLI, STEFANO;VIVALDA, PAOLA MARIA
2015-01-01

Abstract

The investigated area, located in the inner part of the Marche region (central Italy) and belonging to the carbonate Umbria-Marche ridges in the central Apennines, is characterised by very complex geo-structural settings and widespread karst phenomena. Hence, the definition of the relation among the aquifers basing only on the hydrogeological survey is very difficult. The presence of different flowpaths (supposed from the observation of the springs hydrograph) and of hydraulic contact among the aquifers is proved using tracer tests. In particular, the Calcare Massiccio and the Maiolica aquifers are connected under certain tectonic conditions. A new tracer given by a single stranded DNA molecule and a traditional fluorescent dye have been injected into the Montelago sinkhole in different periods (from the recharge to the discharge of the karst system) and recovered in several points along the expected hydrogeological basin, using either manual and automatic sampling and fluorescent traps positioned in creeks, rivers and springs. The DNA molecule is useful to trace surface water and groundwater, is detectable even at very low concentrations, no significant change in water density and viscosity can be observed and its use is not dangerous for the environment (Aquilanti et al. 2013; Sabir et al. 1999). However, DNA is insoluble in groundwater and acts as a particle/colloidal tracer, so it shows a breakthrough curve characterised by higher or lower pulses. The results stress the suitability of DNA as hydrogeological tracer, capable to identify connections among aquifers and study different flowpaths even in high flow conditions when traditional tracers are more and more diluted and often under the instrument detection limit. What is more, Fluorescein tracer allowed for the transport parameter determination, giving mean velocities ranging from 100 to 3000 m/day and mean residence time from some tens to hundreds of hours
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11566/230331
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