Source and behaviour of Ge in agricultural and grazing land soils at European continental scale

Agricultural soil (Ap-horizon, 0–20 cm) and grazing land soil (Gr-horizon, 0–10 cm) were collected from a large part of Europe (33 countries, 5.6 million km2) as part of the GEMAS soil mapping project (GEochemical Mapping... [ view full abstract ]

Agricultural soil (Ap-horizon, 0–20 cm) and grazing land soil (Gr-horizon, 0–10 cm) were collected from a large part of Europe (33 countries, 5.6 million km2) as part of the GEMAS soil mapping project (GEochemical Mapping of Agricultural and grazing land Soil) at an average density of 1 site/2500km2, The area represents soil parent materials with varying geological history, a wide range of climate zones, and landscapes. Germanium concentrations were determined by ICP-MS after a hot aqua regia extraction which will predominantly highlight the non-silicate bound Ge. The median Ge concentration in European soil is 0.037 mg/kg in the Ap and 0.034 mg/kg for the Gr samples.
The Ge maps show a number of fascinating anomalies. The whole Caledonian mountain chain is marked by high Ge concentrations. On first glance this could be taken as a climatic signature, however, Ge does not show any correlation with TOC or rainfall. Also the expected correlation between clay and Ge was not found. Rather high Ge concentrations mark granitic intrusions and related sulphide mineralisation or vein deposits (Portugal, France, Germany, Czech Rep, Sardinia, Greece), carbonate-hosted sulphide deposits (Ireland and in the Alps), iron ore deposits (e.g., Germany) and alkaline Intrusions (Norway, Italy). An anthropogenic impact (e.g. from coal burning or metal smelters) is rarely detected in the European scale maps.