Industrial tailings in Lake Traunsee (Salzkammergut, Austria)

Tailings from salt work and a soda work have been pumped into the southern part of Traunsee (bay of Ebensee) for more than 50 years. Solid wastes have accumulated to form a pile > 40 m high with a total volume of > 3 × 106 m3. The sandy silty mud consists of calcite and other phases of CaCO3, brucite, CaO resp. Ca(OH)2 and gypsum. The chemical environment of the mud is characterized by extreme alkaline pore water (pH > 10 up to 12.5; total amount of pore water: 3 × 106 t) and highly negative Eh-values. These values result from the pumped tailings and from postdepositional chemical processes such as dissolution resp. reaction of CaO, brucite and gypsum and precipitation of CaCO3.