Investigation of a Pit Lake Acting as a Large-scale Natural Treatment System for Diffuse Acid Mine Drainage

摘要

Natural anaerobic biochemical processes used for passive treatment of AMD were observed in the extensive shallow water zone of a pit lake in the former German lignite district of Upper Palatinate. Although continuously fed by acidic metalliferous groundwater, lake-pH increased from 3.5 to circum-neutral over a 15-year-period. The natural attenuation processes were studied and quantified using a regional groundwater flow model linked with geochemical calculations and sediment core analysis. The results indicate that full-scale pit lakes could be used for passive treatment of both diffuse and point source AMD on a much larger scale if the determining environmental conditions were identified.