Sediment cores from the Aegean Sea reveal that human-driven lead contamination began 5,200 years ago—much earlier than expected.
This pollution is tied to shifts in economy and land use, culminating in a significant spike during the Roman conquest, when metal mining and deforestation intensified.
Ancient Lead Pollution: A Discovery from the Aegean
Scientists studying sediment cores from the Aegean Sea and its coastal regions have uncovered evidence that humans were polluting the environment with lead as far back as 5,200 years ago — much earlier than previously believed. A research team from Heidelberg University found that human activity in the region left behind traces of lead contamination, providing not only the earliest known instance of this pollution but also insights into broader socioeconomic changes. The data even reflects major historical events, such as the Roman conquest of Greece.
Tracing Early Human Impact on the Environment
The Aegean region was home to some of Europe’s earliest civilizations, and researchers sought to understand how early human activities impacted both land and marine ecosystems. To do this, they analyzed 14 sediment cores collected from the Aegean Sea and nearby coastal areas.
One core, extracted from a peat bog, contained the earliest known evidence of human-caused lead contamination. The team dated this pollution to approximately 5,200 years ago — over a millennium earlier than the previous oldest recorded instance of lead contamination linked to human activity.
Lead as a Marker of Socioeconomic Change
“Because lead was released during the production of silver, among other things, proof of increasing lead concentrations in the environment is, at the same time, an important indicator of socioeconomic change,” states Dr Andreas Koutsodendris, a member of the Palynology & Paleoenvironmental Dynamics research group of Prof. Dr Jörg Pross at Heidelberg University’s Institute of Earth Sciences.
The sediment cores the Heidelberg scientists analyzed contained lead as well as pollen, which allowed them to reconstruct vegetation development in the Aegean region. The pollen content pointed to how the land was used.
“The combined data on lead contamination and vegetation development show when the transition from agricultural to monetary societies took place and how that impacted the environment,” stresses Jörg Pross.
Roman Conquest and the Surge in Lead Pollution
Lead concentration rose significantly about 2,150 years ago, accompanied by intense deforestation and increasing agricultural use, as indicated by the composition of the pollen spectra. Starting then, lead contamination is also evident in sediment from the floor of the Aegean Sea – the earliest record worldwide of human-caused lead pollution in the ocean, emphasizes Andreas Koutsodendris.
“The changes coincide with the conquest of Hellenistic Greece by the Romans, who subsequently claimed for themselves the region’s wealth of resources,” adds Heidelberg archeologist Prof. Dr Joseph Maran. The Roman conquerors thus pushed the mining of gold, silver, and other metals, with ore extraction and smelting also requiring wood.
The results were published in the journal Communications Earth & Environment.
Explore Further: Ancient Greece and Rome’s Toxic Footprint Found in the Aegean
Reference: “Societal changes in Ancient Greece impacted terrestrial and marine environments” by Andreas Koutsodendris, Joseph Maran, Ulrich Kotthoff, Jörg Lippold, Maria Knipping, Oliver Friedrich, Axel Gerdes, Stefanie Kaboth-Bahr, André Bahr, Hartmut Schulz, Dimitris Sakellariou and Jörg Pross, 30 January 2025, Communications Earth & Environment.
DOI: 10.1038/s43247-024-01921-7
The sediment cores from the Aegean Sea were collected during expeditions of the METEOR and AEGAEO research vessels between 2001 and 2021. The German Research Foundation (DFG) and the European Union financed the research expeditions, with the DFG also funding the most recent research work. Along with researchers from Heidelberg University, scientists from Berlin, Frankfurt (Main), Hamburg, Hohenheim, Tübingen, and Greece also participated in the studies.
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