Bacterial sulphide precipitation in the water column of an acidic pit lake

Congreso SEM-SEA 2012, reunión conjunta de las sociedades españolas de Mineralogía (XXXII Reunión) y Arcillas (XXII Reunión), celebrado en Bilbao entre el 27 y 30 de Junio de 2012A 10 m-thick turbidity layer has been detected in the acidic pit lake of Cueva de la Mora, Iberian Pyrite Belt (SW Spain) (Sánchez-España et al., 2010). This turbidity layer appears immediately below the redoxcline, and shows an intense turbidity maximum at M10 m, and decreases again to near-zero values at M20 m depth. This turbidity layer is closely related to the activity of sulphate-reducing bacteria (SRB), (Wendt-Potthoff et al., 2011). Vertical profiles of bacterially-induced H2S (g) have been measured in different seasons. This H2S reacts with the dissolved metals which, in turn, lead to the formation of different sulphides. The H2S profiles show a similar shape to the turbidity profile, thus suggesting that the turbidity of this lake mostly results from the presence of biogenic sulphide precipitates.Unidad de Mineralogía e Hidrogeoquímica Ambiental, Departamento de Investigación en Recursos Geológicos, Instituto Geológico y Minero de España, EspañaUnidad de Mineralogía e Hidrogeoquímica Ambiental, Departamento de Mineralogía y Petrología, Universidad del País Vasco, EspañaUFZ Helmholtz Centre for Environmental Research, Alemani