Proceedings of the IMWA Symposium 2007: Water in Mining Environments Cagliari, Italy, 27-31 May 2007 PHYSICOCHEMICAL AND MICROBIOLOGICAL STRATIFICATION OF A MEROMICTIC, ACIDIC MINE PIT LAKE (SAN TELMO, IBERIAN PYRITE BELT) Javier Sánchez España 1 , Esther Santofimia Pastor 1 , Elena González Toril 2 , Patxi San Martín-Úriz 2 , Enrique López Pamo 1 , Ricardo Amils 2,3 1 Instituto Geológico y Minero de España, 28003, Madrid, Spain 2 Centro de Astrobiología (CSIC-INTA), E-28850 Torrejón de Ardoz, Madrid, Spain 3 Centro de Biología Molecular (CSIC-UAM), E-280940 Cantoblanco, Madrid, Spain Paper presented to the Symposium of the International Mine Water Association, IMWA’2007 “Water in Mining Environments”, 27-31 May 2007, Cagliari, Sardinia, Italy. Suggested reference for this paper is: Sánchez-España, J., Santofimia, E., González-Toril, E., San Martín-Úriz, P., López-Pamo, E., Amils, R. (2007) Physicochemical and microbiological stratification of a meromictic, acidic mine pit lake (San Telmo, Iberian Pyrite Belt). In: Rosa Cidu and Franco Frau (Eds.), Symposium of the International Mine Water Association IMWA 2007: Water in Mining Environments, 27-31 May 2007, Cagliari, Italy, pp. 447-451. Sánchez-España et al., 2007 446