The occurence of Heavy Metals and Metalloids in Surficial Lake Sediments before and after a Tailings Dam Failure.

Tailings dam failures arc relatively rare but can cause extremely high and long-term impacts on the environment. The Sasa tailings dam collapsed in August 2003 and caused an intensive flow of tailings material through the Kamenica River all the way to Lake Kalimanci, where most of the tailings material discharged. This study deals with the characterization of surficial lake sediments from Lake Kalimanci in eastern Macedonia. Mineralogical, geochemical, and statistical analyses of surficial sediments in two sampling years, before and after the Sasa tailings dam failure, were carried out. To determine the pollution status of surficial lake sediments, two environmental indexes were calculated for 2001 and 2007. Spatial distribution of the analyzed heavy metals and metalloids shows that the highest concentrations were measured on the northern part of the lake, where the Kamenica River enters