A new study published in the journal Communications Earth & Environment revealed that lead pollution in the Aegean Sea dates back about 5,200 years, marking the world's oldest evidence of human-induced lead contamination. The discovery pushes back the earliest known occurrence of lead pollution by approximately 1,200 years.
The research team, led by Dr. Andreas Koutsodendris from the Institute of Geosciences at Heidelberg University, analyzed marine sediment cores from the Aegean Sea and samples from the Tenaghi Philippon peat bog to uncover insights into early human-induced lead pollution. The findings indicate that ancient societies in the region began experimenting with metallurgy and agriculture around this time, contributing to the initial traces of lead contamination.
"We essentially propose that 2,150 years ago we have a major change in ecosystems due to human intervention, and from that point on we enter a completely different state in the natural environment, with humans now determining it," said Dr. Koutsodendris, according to Euronews. This shift correlates with the period of Roman expansion into Ancient Greece.
Starting about 2,150 years ago, researchers identified an increase in lead pollution in marine sediment cores, marking the first recorded large-scale marine pollution from lead in antiquity. This surge aligns with the Roman conquest of the Greek peninsula in 146 BCE. The Romans intensified mining activities for gold, silver, and other metals, driven by the need for resources, contributing to one of the earliest instances of detectable lead pollution.
"These changes coincide with the conquest of Hellenistic Greece by the Romans, who subsequently claimed for themselves the region's rich resources," said Joseph Maran, an archaeologist and co-author of the study, according to El Universo. The extraction and smelting of ores containing lead required large quantities of wood, leading to extensive deforestation in the region.
The research team also examined pollen and spore content in the sediment samples to understand how human activities affected the environment. With the help of pollen, scientists were able to reconstruct the development of vegetation in the Aegean region. The decline in oak pollen indicated deforestation, likely due to agricultural expansion and the need for wood in metal production furnaces.
"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," said Dr. Koutsodendris, according to ABC Color. The combined impact of increased metal production and deforestation altered the environment, marking a transition from agrarian to monetary societies.
"The combined data on lead pollution and vegetation development show when the transition from agrarian to monetary societies took place and how this affected the environment," noted Professor Jörg Pross. This period was characterized by a marked increase in the extraction of precious metals and a shift in land use practices.
"We are doing some studies trying to see if these organisms were affected, to what extent, and what this would mean for food chains in the marine environment," said Dr. Koutsodendris, according to ABC News Australia.