Mercury in European agricultural and grazing land soils

Agricultural (Ap, A_p-horizon, 0-20 cm) and grazing land soil samples (Gr, 0-10 cm) were collected from a large part of Europe (33 countries, 5.6 million km²) at an average density of 1 sample site/2500 km ². The resulting more than 2 x 2000 soil samples were air dried, sieved to <2 mm and analysed for their Hg concentrations following an aqua regia extraction. Median concentrations for Hg are 0.030 mg/kg (range: <0.003-1.56 mg/kg) for the Ap samples and 0.035 mg/kg (range: <0.003-3.12 mg/kg) for the Gr samples. Only 5 Ap and 10 Gr samples returned Hg concentrations above 1 mg/kg. In the geochemical maps the continental-scale distribution of the element is clearly dominated by geology. Climate exerts an important influence. Mercury accumulates in those areas of northern Europe where a wet and cold climate favours the build-up of soil organic material. Typical anthropogenic sources like coal-fired power plants, waste incinerators, chlor-alkali plants, metal smelters and urban agglomerations are hardly visible at continental scales but can have a major impact at the local-scale.