Efficiency of large-scale aided phytostabilization in a mining pond

摘要

Mining activities accumulate large quanti-ties of waste in tailing ponds,which results in several environmental impacts.In Cartagena-La Union min-ing district(SE Spain),a field experiment was carried out in a tailing pond to evaluate the effect of aided phytostabilization on reducing the bioavailability of zinc(Zn),lead(Pb),copper(Cu)and cadmium(Cd)and enhancing soil quality.Nine native plant spe-cies were planted,and pig manure and slurry along with marble waste were used as amendments.After 3 years,the vegetation developed heterogeneously on the pond surface.In order to evaluate the factors affecting this inequality,four areas with different VC and an area without treatment(control area)were sampled.Soil physicochemical properties,total,bio-available and soluble metals,and metal sequential extraction were determined.Results revealed that pH,organic carbon,calcium carbonate equivalent and total nitrogen increased after the aided phytostabili-zation,while electrical conductivity,total sulfur and bioavailable metals significantly decreased.In addi-tion,results indicated that differences in VC among sampled areas were mainly owing to differences in pH,EC and concentration of soluble metals,which in turn were modified by the effect of non-restoredareas on close restored areas after heavy rains due to a lower elevation of the restored areas compared to the unrestored ones.Therefore,to achieve the most favorable and sustainable long-term results of aided phytostabilization,along with plant species and amendments,micro-topography should be also taken into consideration,which causes different soil charac-teristics and thus different plant growth and survival.