Field sampling of soil pore water to evaluate the mobile fraction of trace elements in the Iglesiente area (SW Sardinia, Italy)

•We analysed major and trace elements in soil pore waters of the Iglesiente district.•Waters contain environmentally significant amounts of Pb, Zn, Mn, Cd.•The mobility of metals is mainly controlled by equilibrium with soil phases.•Soil pore waters give realistic estimates of metal mobility and transfer to the biosphere.

Field soil pore water monitoring was applied in a highly heavy-metal contaminated area in SW Sardinia, Italy, as a direct, realistic measure of heavy metal mobility. The main chemistry of pore waters well reflects the local characteristics of soils, ranging from Ca–SO4 to (Ca)Mg–HCO3 to Ca(Na)–SO4(Cl), with a wide range of conductivity. The mobility of Zn and Pb is apparently controlled by equilibrium with minerals such as hydrozincite or smithsonite, and cerussite, respectively. These results allow a correct estimate of the actual environmental risk associated with the presence of heavy metals in soils, and may serve as a supporting tool for phytoremediation planning.