By NECU Team
National Ecological Centre of Ukraine
The chemical analysis of samples collected near the Black Sea coast of Odesa may become crucial evidence in the investigation of ecocide following the destruction of the Kakhovka Hydroelectric Power Plant (HPP) on 6 June 2023. Vladyslav Balinskyi, Head of the Odesa Branch of the National Ecological Centre of Ukraine (NECU), collected seabed sediment samples, mussel rinses,alive species – and two-year-old molluscs in the area of Odesa’s “Dog” beach. The samples will be sent to a specialised laboratory for chemical composition analysis.
This study may serve as key evidence in the criminal case investigating the destruction of the Kakhovka HPP by the Russian army under Article 441 of the Criminal Code of Ukraine – “Ecocide.”
Seabed Samples: What the Environmentalist is looking For
Two years ago, following the Kakhovka disaster, in July 2023 at this very site, Balinskyi documented a mass death of mussels.
After the breach of the Kakhovka HPP dam, a sharp increase in water pollution was recorded — including in the Black Sea. The initial contamination of the Dnipro River occurred within hours, and by 8 June 2023 the polluted waters had reached the Odesa coast. According to satellite data, during the first week after the incident the contaminated river waters extended to the Danube River, covering more than 7,300 km² of the north-western Black Sea shelf.
Odesa coast of the Black Sea, 12 June 2023. Photo by Vladyslav Balinskyi.
By 15 June 2023, around 1,500 km² were affected by massive algal blooms, and areas severely polluted by oil products and organic substances spanned about 6,000 km². In molluscs and fish concentrations of harmful substances significantly exceeded maximum conceivable levels. According to Balinskyi after contaminated water from the Kakhovka reservoir entered Odesa Bay about 50% of all mussels perished.
The Danube is just one example. Apart from the estimated 83 million people living in the Danube basin, another 8 billion people on this planet rely on rivers for all the reasons discussed above, so its clear that in general, healthy rivers are indeed still absolutely essential for almost everyone (1).
(1) More than 100 million people in the world rely on incredibly expensive desalination plants rather than rivers, but let’s not worry about them right now.
This was confirmed by data from the Institute of Marine Biology of the National Academy of Sciences of Ukraine: within just 10 days after the catastrophe about 1 million individuals died – roughly 3.7 thousand tonnes, or 40% of the coastal population in the north-western Black Sea. Viktor Komorin, Acting Director of the Ukrainian Scientific Centre of Marine Ecology, reported that as for the mussels the levels of toxic substances exceeded norms by thousands of times.
This recent study of this part of the Black Sea may become another key piece of evidence in ongoing criminal investigations tied to the 6 June 2023 event at the Kakhovka HPP – in particular the ecocide aspect.
The south-western part of the Black Sea – between Odesa and the Danube Delta – suffered the greatest impact of the Kakhovka wave. Evidence may therefore be found here that the terrorist act by the russianarmy caused ecocide, resulting in a large-scale environmental disaster.
[LEFT] Sampling on a mussel-covered rock. Photo by Vladyslav Balinskyi. [RIGHT] Sampling site
Why Mussels Matter?
Mussels act as natural bio-filters of the Black Sea: each adult specimen can process up to eight litres of water per hour, filtering out suspended particles, bacteria and toxic compounds. Their mass mortality following the influx of Kakhovka waters into Odesa Bay resulted not only in local biomass loss but also in a sharp decline of the sea’s self-cleaning capacity. Effectively, one of the key “purification systems” of the coastal ecosystem vanished, which may facilitate further toxin accumulation and the development of dead zones in bays.
This recent study of this part of the Black Sea may become another key piece of evidence in ongoing criminal investigations tied to the 6 June 2023 event at the Kakhovka HPP – in particular the ecocide aspect.
The south-western part of the Black Sea – between Odesa and the Danube Delta – suffered the greatest impact of the Kakhovka wave. Evidence may therefore be found here that the terrorist act by the Russian army caused ecocide, resulting in a large-scale environmental disaster.
Mussels in the Black Sea. Photo by Vladyslav Balinskyi.
The mussels that appeared in the Black Sea after the destruction of the Kakhovka HPP represent a type of “biological witness” to the state of the sea. As natural filters, they continuously allow seawater to go through and accumulate heavy metals, petroleum products and organic toxicants. An analysis of the young specimens’ chemical composition allows us to understand how contaminated the coastal waters remain after the Kakhovka plume and whether dangerous substances continue circulating in the marine ecosystem.
Such data are vital not only for assessing the environmental consequences of the disaster but also for building an evidentiary basis in ecocide investigations. Mussels born after the tragedy indicate the new “chemistry” of the Black Sea — how capable it is of self-purification and whether its coast is turning into a zone of chronic toxic impact.
Toxic Substances: Threat to People and Animals
The Kakhovka water surge brought to the Odesa coast not only debris of destroyed buildings, household appliances, dead and living animals, uprooted land fragments with reeds and trees but also a mix of bottom sediments from the reservoir and the flooded territories.
The plume of contaminated water consisted of suspended bottom silt, fertile soil layers of the flooded territories, and remnants of washed-away settlements.
Several studies of the Dnipro River water in the disaster zone, as well as of bottom sediments of the Kakhovka reservoir, conducted immediately after and later, showed significant contents of substances hazardous to humans and animals.
Samples collected by volunteers of “Let’s Do It Ukraine” along with scientists in the Dnipro, Dnipro-Bug estuary, and the sea near Ochakiv and Odesa revealed exceedances of maximum conceivable concentrations (MPC) for:
- petroleum products;
- heavy metals: zinc, cadmium, arsenic;
- chlorinated organic compounds: lindane, PCBs.
These substances may cause malignant tumours, nervous-system damage, paralysis and even death. They accumulate in the tissues of living organisms — particularly in adipose tissues — and transfer up the food chain to humans.
Such data are vital not only for assessing the environmental consequences of the disaster but also for building an evidentiary basis in ecocide investigations. Mussels born after the tragedy indicate the new “chemistry” of the Black Sea — how capable it is of self-purification and whether its coast is turning into a zone of chronic toxic impact.
Bottom Sediments — an “Environmental Mine”
In 2024 the Czech team “Arnika” along with Ukrainian partners investigated bottom deposits of the Dnipro and soils of the Zaporizhzhia Region. In samples they found the following:
- heavy metals: manganese, arsenic, cadmium, chromium, lead, nickel;
- residues of DDT, PAHs, and C10–C40 hydrocarbons.
These substances had accumulated for years in the Kakhovka reservoir entering the river via industrial wastewater. After the dam collapse they flowed into the sea, where they may remain as a dangerous “time-bomb” for many years.
Therefore, it is crucial to continue studying the composition of these deposits, predict their impact on ecosystems and develop recommendations to neutralise contaminated areas.
Research of the bottom sediments accumulated in the Kakhovka reservoir is also being conducted by NECU within l the SUNDANSE project. The project aims to develop innovative, sustainable solutions for sediment management in the Danube–Black Sea system, addressing critical environmental problems related to sediments, and supporting ecological resilience of the region’s waterways.
How to establish that Pollutants found in the Black Sea are linked to Kakhovka?
According to Balinskyi, conclusions about the origin of the pollution can be drawn from the ratio of marker pollutants. For example, earlier studies of sediment samples from the Kakhovka reservoir (including the Arnika study) identified high concentrations of nickel, manganese, arsenic and other heavy metals — pollutants typically associated with the mining industry.
The ratio of such contaminants (not just heavy metals but others) in fresh seabed samples may indicate the influence of Kakhovka.
How to prove Ecocide in Court?
The destruction of the Kakhovka HPP dam is a serious violation of international humanitarian law. The criminal actions of the russian military also fall under the legal qualification of war crime in accordance with to Article 8(2)(b)(iv) of the Rome Statute of the International Criminal Court (ICC).
Ukrainian criminal law puts responsibility for the dam’s destruction Article 438 (“Violation of the laws and customs of war”) and Article 441 (“Ecocide”) of the Criminal Code of Ukraine. On 6 June 2023 a pre-trial investigation into the criminal cases regarding the dam’s destruction was initiated. The Kherson Regional Prosecutor’s Office leads the procedural direction of the investigation.
According to the current version of the Ukrainian Criminal Code ecocide is defined as the mass destruction of plant or animal life, poisoning of the atmosphere or water resources, as well as other actions that may cause an environmental catastrophe. Article 441 thus enshrines several forms of ecocide:
- mass destruction of plant or animalworld ;
- poisoning of the atmosphere or water resources;
- committing other actions which may cause an environmental catastrophe.
Legal experts highlight that the most difficult to prove in court is the third form — where an environmental catastrophe or the potential thereof must be demonstrated.
As the authors of the study “Preliminary Environmental and Legal Analysis of the Destruction of the Kakhovka HPP and Its Consequences” stated: “The destruction of the Kakhovka HPP dam caused large-scale, long-term, serious damage to the natural environment which corresponds to the signs and is equated with an environmental catastrophe, has signs of the offence under Article 441 of the Criminal Code of Ukraine. The direct object of the offence provided by Article 441 of the Criminal Code of Ukraine ‘Ecocide’ is the safety of nature as the environment of human habitation. The destruction of the Kakhovka HPP dam led to catastrophic consequences for the natural environment of regional scale, which equals to the object of the offence provided by Article 441 ‘Ecocide’ of the Criminal Code of Ukraine.”
Systematic collection and preservation of evidence regarding the environmental, social and economic consequences of the Kakhovka HPP dam’s destruction are of key importance for qualifying this crime under Article 441 of the Criminal Code of Ukraine as actions that may cause an environmental catastrophe; the participation of independent researchers ensures the objectivity, reliability and international legitimacy of the evidential base.