Microplastics contaminate archaeological remains

For the first time, researchers have discovered evidence of microplastics contamination in archaeological soil samples. In samples from the first or early second century excavated in the late 1980s, the team noticed tiny microplastic particles in deposits more than seven meters deep.

Preserving archaeology in situ is the preferred approach to managing historic sites for a generation. But the research team says it could lead to a reconsideration of this approach as the tiny particles potentially jeopardize preserved remains.

Microplastics are tiny plastic particles ranging from 1μm (one thousandth of a millimeter) to 5 mm. They come from a wide variety of sources, from shredded larger pieces of plastic or lumps of resin.

The study, published in the journal Science of the Total Environment, was carried out by the universities of York and Hull.

Prof. John Schofield of the Department of Archaeology at the University of York said: “This feels like a pivotal moment confirming what we have been expecting. that archaeological remains ready for investigation, thought to be intact, are in fact contaminated with plastic… This includes deposits sampled and preserved in the late 1980s.”

“We are familiar with plastics in oceans and rivers. But here we see that our historical heritage contains toxic elements. The extent to which this contamination jeopardizes the evidential value of these deposits and their national significance is what we will try to find out next.”

“We think of microplastics as a very modern phenomenon because we have been hearing about them for the last 20 years, ever since they were declared widespread in 2004. “

“This new study shows that the particles have also infiltrated archaeological deposits.  Based on particles found in archived soil samples taken at Wellington Row in York in 1988, it suggests that microplastics probably migrated into remains at a similar time as the oceans.”

The study identified 16 different types of microplastic polymers in both contemporary and archived samples. 

“Where this becomes a concern for archaeology is how microplastics may compromise the scientific value of archaeological deposits.  Our best preserved remains – for example, the Viking finds at Coppergate – were in a consistent anaerobic waterlogged environment for over 1000 years, which preserved organic materials incredibly well.  The presence of microplastics can and will change the chemistry of the soil, potentially introducing elements which will cause the organic remains to decay.  If that is the case, preserving archaeology in situ may no longer be appropriate,” said David Jennings, Chief Executive of York Archaeology.

The research team says further research into the potential impact of human made chemicals on archaeological remains will be a priority for archaeologists.