Earliest ever evidence of lead pollution found in the Balkans

What is it about?

Sometime around 3600BC, people in the Balkan peninsula reached a major milestone: their mining and metal smelting created enough pollution for us to detect it today. Our research has revealed this was the beginning of the Bronze Age in the region, and the birth of large-scale metallurgy in Europe. To give some context for how early this was: at the same time, the first ever writing was just being developed in Sumer, Mesopotamia, while Britain was still in the Stone Age. Egypt’s first pyramids were still a thousand years in the future. We already knew about these Bronze Age Balkans from patchy archaeological records of axes, adzes and beads. But we are now able to learn more about them thanks to traces of pollution they left behind. Metal is extracted from its ore through a process known as smelting. This releases microscopic particles of lead into the atmosphere, which are then transported long distances by winds until they settle on the ground. Peat bogs are ideal repositories for these particles because atmospheric transport is the main pathway by which pollutants can reach these sites. As peat bogs grow in small layered increments each year, they can give us a clear history of the environment in which they grew. When many such chemical analyses of known ages from the many layers of the bog are put together, a sequence of changing pollution can be developed.

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Why is it important?

We present the first such record of changing pollution from south-eastern Europe, reconstructed from the changing concentrations of lead in a peat deposit from western Serbia. We found evidence of raised lead levels dating back to 3600BC. This is the oldest known environmental metal pollution on Earth, and places the Balkans very much at the forefront of the period of metallurgical discovery and development in the very earliest Bronze Age. Previously the oldest known European environmental pollution happened about 3000BC in southern Spain. Our findings pushes this back by more than 500 years. Indeed, it would take western Europe another 1,000 years to catch up to the same level of metallurgical development.

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