Groundwater contamination: Environmental issues and case studies in Sardinia (Italy)

In this study, the arsenic (As), cadmium (Cd), lead (Pb), and zinc (Zn) contamination has been evaluated in the groundwater of Sardinia (Italy). Contamination by such chemical species is among the most relevant risks for many populations, thus giving general interest to the case studies presented in this chapter. A brief introduction about the European legislative framework is given, followed by a description of the analytical methods used and a discussion of the results. Two areas were selected as case studies: the Osilo area, devoted to geogenic degradation, and the Iglesiente-Fluminese mining district mainly affected by anthropogenic contamination. The geochemical controls on the natural baselines of As, Cd, Pb, and Zn are generally related to natural sources, mostly derived from water-rock interaction processes in areas of known mineral occurrences. In fact, median concentrations of the investigated elements in the mineralized areas are much higher than those of the corresponding median regional values and sometimes exceed the Italian limits for drinking water. In the Iglesiente-Fluminese mining district very high concentrations of Cd, Pb, and Zn were measured in groundwater that circulates in areas affected by past mining activities. The results of this study clearly show that the understanding of the trace metal pollution trends, and the distinction of the anthropogenic impacts on the aquifer systems, is essential for evaluating the natural baseline of contaminants as well as for distinguishing the relevant processes that influence their chemical characteristics. Such information, together with the geological features of a region and/or subregion, should be taken into account prior to defining regulatory limits of contaminants in groundwater.