Lead, Zinc, Arsenic and Copper Pollution in the Alluvial Plain of a Mining Wadi: The Beal Case (Cartagena–La Union Mining District, SE Spain)

The distribution and mobility of heavy metals in the non-saturated zone of the alluvial plain of a wadi in the Cartagena–La Union mining district was investigated. The elemental chemistry of soils, in-depth sediments and different plant species (namely Hirsfeldia incana, Ditrichia viscosa and Piptatherum miliaceum) was carried out by using X-ray fluorescence and X-ray diffraction techniques. Potential mobility of metals was assessed by using lixiviation test runs (DIN 38414-S4). Concentrations detected in soils and sediments were higher than the acceptable limits reported in official regulations. Regarding metals mobility, values obtained for Pb, Zn and As exceed the limits established by European Union for DIN 38414-S4 leachates. Whilst the obtained leaching percentages for Pb, Cu and As were not especially high (<2%), Zn exhibit a very high leaching potential (up to 60% of the total metal content), involving potential risk of pollution events.