When did the metallurgy at Alntorpshyttan start to affect Norasjön, Bergslagen, Sweden? : Using lake sediments to trace a historic, site-specific, metallurgical activity

A common view in today’s society is that natural background conditions is found just prior to the start of the industrialization. By employing this view in environmental work, it neglects the human impact attributed to historical site-specific activities such as metallurgy. These activities have been widespread throughout Sweden, reaching far back into history. It is therefore necessary to determine the site-specific background conditions in order to assess the impact these activities have had. This study investigates the start of the blast furnace Alntorpshyttan in Bergslagen by conducting geochemical analyzes using sediment profiles in Norasjön as a natural archive. This was coupled with an indirect dating method based on the immigration spruce (Picea abies) and the historical atmospheric lead (Pb) pollution. The earliest sign of human activities takes place at 1800 BP, possibly due to farming activities. Based on the increases in iron coupled with increases in other ore-related elements (e.g., Magnesium and copper) I placed the start of Alntorpshyttan in the early/late 13th century. This is consistent with the rapid expansion of blast furnaces throughout Bergslagen. Based on these results, I conclude that historical small-scale metallurgical activities have had a significant impact on local lake systems and potentially a cumulative effect further downstream