A photograph looking down a long straight road in the Ukrainian countryside fringed by trees. In the foreground at the side of the road, a huge missile is poking out of the ground.

Ukraine's rich cultural heritage is facing an existential threat from the Russian invasion, but it is also being damaged by microorganisms that are damaging parts of it ©Shutterstock/Drop of Light

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How scientists are saving Ukraine's cultural heritage during the Russian invasion

Standing at the heart of Kyiv for over a thousand years, the Saint Sophia Cathedral is one of Ukraine's most important cultural sites.

Sadly, the medieval murals that line its walls are being degraded by microorganisms. In the midst of the invasion of Ukraine by Russia, scientists have been working out how to protect these historic artworks from further damage. 

While Ukraine is currently in the grip of war, scientists have been working across borders to protect its cultural heritage.

Some of the nation's most significant works of art were painted on the walls of the Saint Sophia Cathedral around 1000CE. These artworks are now being slowly erased by microscopic organisms. By figuring out what is causing this damage, and how it is happening, researchers hope to counter this threat and save the paintings.

But faced with the Russian occupation of Ukraine and their attempts to violently destroy and assimilate much of the nation's cultural identity, the work to preserve Saint Sophia and its artwork has taken on an entirely new meaning.

Dr Javier Cuadros is a senior researcher at the Museum and a co-author of the paper who played a crucial role in getting the paper over the finishing line during the invasion of Ukraine.

'We were cooperating with them in this very difficult situation,' explains Javier. 'At the very beginning of the war Kyiv was quickly attacked. At that time, we had received the first comments on the paper from the reviewers of the scientific journal but of course it was then impossible for our colleagues in Kyiv to continue working because they had to suspend their lives and leave their homes.'

'Our Ukrainian colleagues are extremely happy that this has finally been published. This paper means a lot to them, as this cultural site is part of their heritage and publishing our study was an act to manifest and protect their cultural identity.'

'It has been very emotional from the very beginning, through the worst of it.'

The paper has been published in International Biodeterioration and Biodegradation.

A picture of Saint Sophia Cathedral, showing its numerous golden and green domes and white exterior.

The thousand-year-old Saint Sophia Cathedral is one of the most significant cultural sites in all of Ukraine ©Shutterstock/Baturina Yuliya

Protecting the past

About a decade ago, curators and researchers working in Ukraine's Saint Sophia Cathedral noticed something concerning. Some of the historic and culturally important murals that adorn the walls of the cathedral, which sits at the heart of Kyiv, were becoming damaged.

The murals had developed dark spots on the plaster, accompanied by flaking away. In a bid to protect and restore the art, the researchers set about in earnest to find out what was going on.

Their first few tests allowed them to find the microbial culprit. In addition to damage by people, animals and plants, historic murals around the world are frequently at risk of decay by a whole host of microbial communities.

'The two main groups of microorganisms that can be abundant in great quantities are bacteria and fungi,' explains Javier. 'Sometimes there is also algae, but they are typically visible, and in this case there was no algae visible.'

The team took DNA samples from the damaged walls of the cathedral and compared these to samples from undamaged areas. From this, they were able to see that, while the levels of bacteria in both regions were similar, the damaged parts of the church had much higher levels of fungal DNA.

This meant they could be fairly certain that it was fungi that were responsible for the damage. The next step was to assess exactly what that damage was and how it was occurring, before hopefully arriving upon a way to prevent it. 

A photograph of the medieval mural. It shows the basic figure of a person looking forward, with an reddish-brown head dress. The wall on which the picture is painted is covered with small brown-black dots.

The medieval paintings are being damaged by fungi, which cause dark spots to appear on the surface of the plaster ©Marina Fomina 

'As part of the investigation, my colleagues discovered cracks and voids within in the fabric of the wall and some relatively big crystals that looked completely foreign,' says Javier. 'They were very different from the general fabric of the plaster.'

'A first chemical assessment of the crystals was done using microscopic techniques in Kyiv, Rome and Dundee that showed they were an organic, calcium-rich substance. The identification was completed here at the Museum, using micro-X-ray diffraction. We concluded that this was an organic salt called calcium malate. Typically, fungi excrete other organic substances, but this one is very rarely secreted.'

Calcium malate had been found on deteriorated murals only a couple of times before, in a monastery in Barcelona and in the tomb of Tutankhamun.

The calcium malate crystals are simply a by-product of the fungi as it dissolves inorganic components in the plaster to extract mineral nutrients. The crystals are formed from the reaction between malic acid and the calcium from the plaster.

Malic acid is a very common compound, produced in the cells of every living organism, but why the fungi are secreting it is still unknown. The acid dissolution of plaster and the deposition of crystals within the plaster work, together with the 'pushing action' of fungi as they spread is breaking the plaster apart, staining it and causing it to degrade.

Now that the researchers and curators in Kyiv know exactly what is going on in the walls of the cathedral, they hope to be able to prevent it and preserve the paintings for years to come by, for example, applying fungicide to the walls.

Preserving Ukraine's heritage in a time of war

When the project to protect the Saint Sophia's murals first started, none of the researchers could have predicted quite how it would end.

On 24 February 2022, the biggest threat to the cathedral was no longer the fungi growing through the plasterwork, but the column of Russian tanks and armoured vehicles making its slow and eventually fateful way towards Kyiv, as countless Russian missiles fell across the city and surrounding districts.

In the face of what many feared would be a brutal occupation of the capital, many residents fled while they had the chance. 

The front of an ornate building in Khakiv, Ukraine, which has been extensive damaged by warfare. The plastwork is crumbling, and the windows smashed.

The war has brought a new threat to Ukraine's heritage, but the researchers are doing their best to give it the best chance ©Shutterstock/Drop of Light

'The first author of the paper, Marina, and her husband fled Kyiv for two or three months when they thought the attack was imminent and they could escape the city,' explains Javier. 'Then after the Russians retreated from the area, they returned to the capital and went back to work.'

'They and the other colleagues collaborating in this work are well, thank goodness. It is quite amazing to see their resilience.'

The existential threat and horrific loss of life faced by Ukraine and its citizens has brought the efforts to protect the nation's deep cultural heritage into stark relief. But amongst the destruction and terror left in the wake of the Russian soldiers, hope still shines through.

'Marina has been telling me about how they helped each other, cooking and shopping for elderly neighbours who were in need or couldn't go out, caring for and keeping company to the lonely,' says Javier. 'It has been a lesson in human solidarity and maintaining cohesion in this very difficult situation they were finding themselves.'

'We dedicated the paper to the courageous Ukrainian people. Because we thought that they deserved this.'