GcBÜK400 — Lead in the upper floor

Lead is a toxic heavy metal and, due to its diverse industrial use, is ubiquitous in the environment. The input sources are not limited only to the range of ore deposits (especially lead sulphide and its oxidation minerals). Lead is also recorded anthropogenically through the prevention of lead, copper and zinc ores, the long-range exhaust pollution of motor vehicles (until the introduction of lead-free gasoline up to 60 % of atmospheric pollution), recycling plants of lead scrap, the use of heavy metal sewage sludges and composts, as well as by coal incineration plants. For uncontaminated soils, a Pb content of 2 to 60 mg/kg is indicated depending on the starting rock. The average Pb concentration of the upper continental earth crust (Clark value) is 17 mg/kg, the area-related mean Pb content for the Saxon main rock types is 20 mg/kg. The rocks of Saxony have no or only a small geochemical specialisation in terms of lead. In the northern or northeastern part of Saxony, relatively low levels of Pb occur in the upper soils above the curler sediments of the Känozoikum (periglaziary sands, gravel, clay, loess) and the granodiorites of the Lusatia. With the looser sediments, the Pb content increases slightly with increasing tone content. The weathering soils above the solid rocks of the Ore Mountains, Vogtland and partly the Elbe Zone usually have significantly higher lead contents, which are caused by a relative enrichment in the base rocks. The most polluted area in Saxony is the Freiberg region. Due to the economically important polymetallic mineralisations (Pb-Zn-Ag), which are also relatively widespread in terms of area, there was a particularly strong Pb enrichment in the secondary rocks and consequently also in the formation of soils over the gneisen. In addition, enormous anthropogenic loads have been caused by the centuries-long prevention of primary ores and more recently in the recycling of lead batteries. Particularly high levels of Pb occur in the immediate vicinity of the metallurgical sites, including the main wind directions, in the central part of the quartz-sulfide mineralisations and in the river floodplains. Other areas with large-area elevated levels of Pb are mainly in the Osterzgebirge, in an area that extends from Freiberg in a southeast direction to the border in the Altenberg area and in the ore areas of the Middle and West Ore Mountains, such as Seiffen, Marienberg — Pobershau, Annaberg, Schneeberg, Schwarzenberg and Pöhla. However, the percentage of Pb minerals in the ores of these regions is significantly lower. Due to frequent association of Pb and As in the mineralisations, the distribution area of the increased Pb levels in the Osterzgebirge and subordinated in the West Ore Mountains as well as in the meadows of the Freiberger and United Mulde is similar to that of the Arsen. The floodplains of the Freiberger Mulde produce extremely high lead content from the Freiberg deposit area, which continue to the floodplains of the United Mulde in northwestern Saxony. The floodplains of the Elbe and the Zwickau Mulde also have areas with higher lead levels due to geogenic or anthropogenic sources (storages, industry) in the catchment area. The lead content of the soils in the Freiberg area and in the meadows of the Freiberger and United Mulde partly exceeds the test and measure values of the Federal Soil Protection and Contaminant Ordinance (BBodSchV)