Environmetal Impact on soil, water and plants from the abandoned Pan de Azúcar Mine

JOSEFINA PLAZA CAZÓN; LEONARDO BENÍTEZ; JESICA MURRAY; ALICIA KIRSCHBAUM; KIRSCHBAUM PABLO; DONATI EDGARDO

Simposio; 20th International Biohydrometallurgy Symposium; 2013

Pan de Azúcar mine is located at 3700 m.s.n.m in Jujuy, Argentina. The main mineral is a vein-type with a high sulphide content (main mineralogical species are pyrite, sphalerite, and galena) and also rich in silver. Extractive activities focusing to lead and silver extractions ceased in 1986 and the site was abandoned without adequate mine closure. Several tons of tailings were accumulated close to the mine and were eroded due to the strong winds and summer floods; that provoked the dispersion of polluted materials into surrounding environment contaminating soils and water which represents a health hazard. The impact of that pollution was evaluated determining the density and the composition of the vegetation around the tailings. Also soil and plants samples were collected and their metal contents were determined. Several vegetal species but Deyeuxia breviaristata was the main native plant in the most polluted soils and its biomass had the highest concentration of zinc and lead. Although sampling was done in the dried season, some evidence of acid mine drainage (AMD) from the tailings was found. ADM samples were collected and their toxic effects were analyzed by ecotoxicology assays employed Lactuca sativa L. Seeds; CI50120 of 0.03 % v/v was determined. From mineral and ADM samples some iron- and sulphur-oxidizing microorganisms were isolated and also characterised by molecular techniques (fluorescence in situ hybridisation and 16S rRNA gene sequencing). AMD potential was evaluated for different tailing samples inoculating native microorganisms; deeper samples produced drainage with pH close to 1 and released iron above of 1000 ppm. AMD can reach Cincel River (close to the mine) which is the main tributary of Laguna Pozuelos (just 25 km from the mine). Laguna Pozuelos is a Natural Monument, Biosphere Reserve and Ramsar site, with slightly alkaline water and the natural habitat for several waterbirds.