THE DISTRIBUTION OF CD, CU, PB AND ZN IN TOPSOILS OF OSNABRUCK IN RELATION TO LAND-USE

The subject of this paper is heavy-metal concentrations in topsoils in Osnabruck and its environs. Two-hundred and twenty-six soil samples were taken from a depth of 2-10 cm over an area 16 x 16 km(2). The pH of the samples was determined and the Cu, Zn, Cd and Pb concentrations measured. The largest accumulations compared with the limits specified by VDLUFA(1) (Kloke, 1980) were found for Pb. Throughout the area investigated, 18% of the samples contained > 100 mg/kg Pb. With a few exceptions the cadmium concentrations may be described as normal, but the accumulations of this highly mobile heavy metal at certain locations must be regarded as critical. A noticeable feature in the countryside around Osnabruck was the increased concentration of heavy metals in the sedimentation area of the river Hase (up to 200 mg/kg Cu in the soil) and the river Dute (up to 530 mg/kg Pb and 1530 mg/kg Zn in the soil) as well as in the vicinity of metal-working factories. Elevated heavy-metal levels of geogenic origin were detected on the hill crests of the Teutoburger Wald. In the town itself the highest concentrations were found for Pb and Cu: 21% of the samples contained > 100 mg/kg Pb and 15% contained > 100 mg/kg Cu. The extremely high values around a metal-working factory in Widukindland (north-east of Osnabruck) were a striking feature. When recorded in the form of a soil pollution map the results of such a survey make it possible to identify unusually polluted areas; they can also be analyzed further to provide more detailed information. In view of some considerable heavy-metal concentrations in the soil of Osnabruck it would be advisable to investigate these locations more closely for their effects on plant nutrition and the food chain and to prevent a direct hazard to children playing there.