METAL LOAD RECORD IN URBAN LAYERS OF TWO MEDIEVAL TOWNS

Modern urban soils normally contain elevated concentrations of toxic heavy metals like lead, nickel and cadmium. However, little is known about the metal contents of older urban deposits. In this paper we discuss the human impact on geochemistry of archaeological layers representing time span from medieval (13th century) to recent times. The samples have been collected from two formerly Swedish towns, Turku (SW Finland) and Wiborg (NW Russia), and analysed with ICP-AES.

The results from the both studied towns show that the archaeological layers dating back to 13th to 17th century have been heavily contaminated by lead, copper, zinc and chromium. They reflect the load caused by blacksmiths, glass makers, potters, tanners etc. The heavy metal concentrations in medieval soils exceed those analysed from modern soils and can only be compared with the values detected close to metal smelters or mining areas.