Arsenic and heavy metal contamination of soil and vegetation around a copper mine in Northern Peru

At present, very little information is available on either the environmental impact or the biogeochemistry of mine sites in Latin America. Here we present preliminary results on contamination of soils and plants around a copper mine in the Andes of Northern Peru. Plants and soils were sampled at six sites ranging from low (S1) to high phytotoxicity (S6); samples were analysed for concentrations of As and heavy metals. Stepwise multiple regression analysis was used in order to determine the soil factors that significantly influenced As and metal availability. High As and Cu concentrations in soil extracts (ammonium acetate-EDTA), in addition to low pH and high Al availability, seem to be the most important soil factors that limit plant performance around the mice. A high organic matter content favoured Cu and Al extractability. Nevertheless, phytotoxicity was more intense at sites with low organic matter concentrations. Unusually high concentrations of As and metal concentrations were detected in leaves of some species (e.g. in Bidens cynapiifolia up to 1430 μg/g dry wt. As, 437 Zn, 620 Cu, 6510 Al and 5.7% Fe) while others (e.g. Eriochloa ramosa) more effectively restricted metal transport to the shoots. These plant species seem interesting for future investigations on both metal tolerance mechanisms and revegetation of contaminated soils at the numerous mine sites located at high altitudes in equatorial regions.