Assessment of post-recultivation migration of heavy metals in the tailings pool – vegetation cover system of a mountain region

Abstract

The aim of the research. For the conserved Unalsky tailing dump, to evaluate how the location of samples – above or below the slope – affects the accumulation of six heavy metals (Cu, Mn, Ni, Pb, Zn, Cd) in wild vegetation. Methods. Phytomass samples were taken on the reclaimed surface and adjacent areas. Concentrations were determined by ICP-MS and atomic emission spectrometry. Statistical processing was performed using correlation analysis and PCA, compared with the MPC through the coefficients of excess. Results. Higher up the slope, Ni and Mn dominate in plants, while Pb and Cd are at a low level. Below the tailings dump, the picture is changing: the excess of the maximum permissible concentration for lead reaches twenty times the values, and cadmium is above the norm in 84% of the samples taken. PCA showed that the direction from the source explains almost a third of the variability (32.6%) and confidently divides the samples into two groups. This is confirmed by the fact that fine particles enriched in Pb and Cd migrate downhill and accumulate in biota. Conclusions. The key factor determining the set of metals in vegetation is the spatial position relative to the tailings dump. Sorption barriers and liming are necessary for zones with Pb–Cd anomalies, and antifiltration screens are necessary for zones with Ni–Mn. For timely reclamation adjustments, it is necessary to switch to online monitoring that combines seismic data and rapid analysis of phytomass.