Best tracer selection for hydrogeological investigations: preliminary results from laboratory test

Tracers techniques are a good tool to investigate groundwater dynamics; they are essential to perform measurement of hydrogeological parameters of aquifers. This study was aimed at characterizing adsorption, effective porosity and pore water velocity in soil samples collected in a hydrographic basin of Marche Region (Italy). This basin has the typical geologic and hydrogeological features of many basins in Central Italy. Therefore. the principal aim is to evaluate the best tracer to be used for hydrogeological purpose (i.e. groundwater tracer test and aquifer parameter estimation). Adsorption has been investigated by means of laboratory batch tests using different tracers and involving different soils. In literature some application of tracers both to laboratory scale and to field scale can be found. Column tests have been performed also to test the effectiveness of different test equipment and to investigate the influence of some test parameters on the calculation of effective porosity and pore water velocity. These considerations and test results are very useful to advise the choice of the best tracer to be used in tracer field tests.