Mercury content in the European Union topsoil

Mercury (Hg) distribution in topsoil (0-20cm) is influenced by climate, soil properties, vegetation.  In adiiton to the natural factor, mercury has high values close to past mining activities and coal combustion sites. High concentrations of mercury have been found close to well-known mining sites like Almaden (Asturias, Spain), Mt. Amiata (Italy), Idrija (Slovenia) and Rudnany (Slovakia). Overall, the stock of Hg in EU topsoil is estimated to c.a. 44.8 Gg with a median concentration of 38.3 μg kg−1; 10% of the area exceeds the 84.7 μg kg−1 and 209 Hg hotspots (top 1%) have been identified with concentrations >422 μg kg−1.In a more detailed investigation, 42% of the hotspots were associated with well-known mining activities while the rest can be related either to coal combustion industries or local diffuse contamination. In total 209 hotspots were identified, defined as the top percentile in Hg concentration (>422 μg kg−1). 87 sites (42% of all hotspots) were associated with known mining areas. The sources of the other hotspots could not be identified and may relate to unmined geogenic Hg or industrial pollution.