Effect of marble waste and pig slurry on the growth of native vegetation and heavy metal mobility in a mine tailing pond

The effect of marble waste and pig slurry on the growth of native vegetation and heavy metal mobility in an abandoned Pb-Zn-Cd tailing pond (southeast Spain) has been investigated. Different treatments were carried out in four plots, (1) pig slurry, (2) marble waste, (3) marble waste + pig slurry, and (4) control. Plant cover, richness, biodiversity, metal in plant tissues, soil physicochemical properties and water and DTPA extractable metal concentrations of bare and rhizosphere soils were analyzed after one year from the application of the treatments. The pond materials contain large amounts of Fe-oxyhydroxides, sulphates, and heavy metals. Before the application of amendments, soil remained bare and organic matter content was very low. After applications, a native vegetation cover (25–30%) with the highest biodiversity (H = 1.1–1.3) and a richness of 10 was reached in the plots amended with pig slurry. The establishment and development of vegetation improved soil quality and decreased the metal availability, even more efficiently than the direct effect of the amendments. Among indigenous vegetation, Piptatherum miliaceum (L.) Cosson showed the characteristics of Pb phytostabilizer plant species. This study confirms the effectiveness of a vegetation cover for the persistence of the reclamation processes in bare mine soils under Mediterranean semiarid conditions.

► Piptatherum miliaceum showed the characteristics of Pb phytostabilizer plant species.
► Pig slurry and marble promote native vegetation growth and reduce metal mobility.
► Rhizosphere soils were inclinable to improve the soil quality.