Enrichment and distribution of elements in flood-plain soils of the bitterfeld industrial area—studied by neutron activation analysis

Bitterfeld is an industrial area of central Germany which has been exposed to extraordinarily high concentrations of anthropogenic environmental pollutants for many decades. High concentrations of organic (e.g. PCB and hydrocarbons) as well as inorganic (e.g. heavy metals) pollutants are present in the soils. The major objectives of this study were the quantification of inorganic components in the soils and the verification of the analytical results through different analytical methods. The origin of the anthropogenic heavy metal input in the study area is twofold: first, at present, industrially produced fly ash is deposited upon flood-plain sediment and second, sedimentation processes during the flood periods of the Mulde river over the past number of years. Flood-plain soil profiles were studied and characterized by four horizons, designated as Ah, Bv, Gor and D. Samples were taken at 10-cm intervals down to a total depth of 170 cm. All components studied were analyzed using activation methods with reactor neutrons and accelerator-produced high energy bremsstrahlung photons. Thirty-four elements and their vertical distributions throughout the profile were examined. The results are interpreted in relation to geochemical and soil-related physical parameters, e.g. pH, clay content, density and organic components. We conclude that for a number of elements, estimations of the anthropogenic input and their mobility behaviour can be made. For instance, the distribution characteristics of calcium, nickel, zinc, molybdenum, arsenic, antimony, lead and uranium indicate mainly an anthropogenic input, whereas the distribution of scandium, titanium, rubidium, yttrium, zirconium, tin, cesium and the rare earths are obviously to a large extent of geogenic origin. For the classification of the depth distribution of the elements studied, a hierarchic cluster analysis was carried out, the results of which were correlated subsequently with the help of canonic discriminance functions.