Impact of historical metalworks on the concentrations of major and trace elements in sediments: a case study in Finland

The concentrations of major and trace elements were determined (aqua regia leach and ICP-AES analyses) in stream, lake and dredged sediments downstrea m of the historical Antskog iron- and copperworks, S.Finland. The levels of Ag, Cd, Cu, Pb and Zn are highly elevated in all studied sediment types: r oughly half of the studied lake-sediment samples contain > 5 ppm Ag, > 15 p pm Cd, > 0.1% Cu, = 0.1% Pb and > 0.3% Zn. In the dredged sediment material located onshore, the concentrations of Ag, Cu and Pb are comparable to tho se in the polluted lake-sediment samples, while in stream sediments elevate d metal concentrations are found especially in samples characterised by hig h concentrations of organic material. The source of the elevated metal conc entrations is the historical metalworks at Antskog, mainly the copperworks of the 19th century. Compared to the limit values for contaminated soils in Finland, the concentrations of Cu, Pb and Zn are on average elevated by fa ctors > 10 in the polluted horizons of lake sediments, > 5 in the dredged s ediment located onshore and > 2 at the most heavily contaminated site in th e stream. Since the surface waters in the area are used for agricultural pu rposes and for various leisure activities, it is necessary to make further detailed investigations into the extent of the metal pollution and to deter mine species, mobility and bioavailability of the metals. (C) 2000 Elsevier Science Ltd. All rights reserved.