Impact of pollution at a Stone Age rock art site in Oslo, Norway, studied using lead and strontium isotopes

Naturally occurring strontium and lead isotopes were used to study the impa ct of anthropological pollution on a c. 4500-year-old rock carving in Oslo, Norway. Strontium analyses have shown that road-salt from de-icing of a ne arby road has accumulated in the soil surrounding the carving. Upon rainfal l this salt is redissolved and drains over the rock carving. Analyses of th e lead isotopic system have confirmed the impact of traffic from the nearby road on the rock carving site, but also indicate other sources of lead in the Oslo area and pollution in general. The rock carvings Ekeberg are at hi gh risk as, apart from natural weathering, they are exposed to the depositi on of road salt, emissions from nearby traffic, local and long distance atm ospheric pollution and meteorological inversion effects during the winter.