Heavy metal contents in soils and native flora inventory at mining environmental liabilities in the Peruvian Andes

Inadequate waste management in Mining Environmental Liabilities (MEL) represents a risk for the environment and human health and generates social problems. The aim of this article is twofold: i) to evaluate the environmental quality of soils from a geo-ecological perspective; and ii) to inventory native flora around two MEL in the Hualgayoc district in the Peruvian Andes. Soil samples collected for topsoil (upper 30 cm; i.e., soil arable layer) and subsoil (30–60 cm) were classified as Gleyic Cambisols and showed extremely acid pH (3.50–4.19 in site #1 and 2.74–4.02 in site #2). The mineralogical composition of soils is dominated by illite, kaolinite, quartz, and jarosite. The concentrations of six potentially toxic elements (Pb, Zn, As, Cu, Ag, and Cd) were determined. High concentrations of Pb (4683 mg kg⁻¹), Zn (724.2 mg kg⁻¹), Cu (511.6 mg kg⁻¹), Ag (33.4 mg kg⁻¹), and As (3611 mg kg⁻¹) exceeded the maximum permissible limits for agricultural soils according to Peruvian and Canadian regulations. Applied geochemical indexes classified some of the soils as extremely polluted and therefore the studied MEL represent a very high ecological risk. Twenty-two species of native flora belonging to 12 family species were inventoried in such contaminated sites thus having the potential to be used for phytoremediation purposes.