The main concern is corrosion. Metal containers, shells, bombs, mines, and barrels lying on the seabed are deteriorating after decades under water.
If they break open, they may release toxic substances, including sulfur mustard, tabun, adamsite, chloroacetophenone, and arsenic compounds.
Some of these agents can cause severe skin and respiratory injuries after direct contact. Others are toxic to marine organisms and can remain in seabed sediment for long periods.
The issue has gained renewed attention around European Maritime Day, marked on May 20. The day was established in 2008 to highlight the importance of seas and oceans for Europeans and the European Union economy.
It also promotes the “blue economy,” which includes shipping, fishing, tourism, and the protection of marine ecosystems.
According to data collected under the international CHEMSEA project, carried out from 2011 to 2014 by researchers from Poland, Germany, Lithuania, Sweden, and Finland, about 50,000 tons of munitions containing chemical warfare agents were dumped in the Baltic Sea.
Most of the material was left there after World War II. The Allies had taken over vast German stockpiles of chemical weapons and decided to dump them in European seas, including the Baltic. The operations were conducted mainly in the second half of the 1940s.
The documentation was often incomplete, and the dumping methods would not meet modern environmental safety standards.
Some munitions were thrown into the sea in barrels and crates. In some cases, entire transport ships were sunk with their cargo.
The largest known concentration is in the Bornholm Deep, where about 35,000 tons of chemical weapons are believed to lie at depths of 70 to 105 meters. Those weapons contain an estimated 13,000 tons of chemical warfare agents.
Another major dumping area is the Gotland Deep, where at least 2,000 tons of chemical weapons were deposited at depths of 80 to 100 meters.
Chemical weapons were also dumped in the southern Little Belt and in the area of the Gdańsk Deep.
Researchers stress that the problem is not limited to official dumping sites. Documents from the Polish Academy of Sciences' Institute of Oceanology indicate that some cargo may have been thrown overboard during transport. This means individual munitions or clusters may lie outside designated areas.
For decades, much of the information about these operations remained classified. Some details were released only in the late 20th century. Experts say this still makes it harder to establish precise locations, assess the condition of the munitions, and measure the environmental risk.
In the past, researchers assumed that the low solubility of some chemical warfare agents and chemical processes in seawater would limit the threat.
More recent findings suggest that dumping the weapons did not neutralize the problem. It moved it out of sight and delayed its consequences.
The risk is now more serious because of growing offshore development, including wind farms, gas pipelines, and undersea cables.
Such projects require detailed seabed surveys. Accidentally disturbing corroded containers could endanger the marine environment and people working at sea.
Scientific institutions and marine protection organizations are focusing on monitoring the seabed, mapping dumping sites, and assessing risk. International research projects such as ChemSea, Daimon, and MuniMap have tested ways to detect munitions, monitor contamination, and examine possible methods for neutralizing the most dangerous objects.
Scientists warn, however, that large-scale recovery of chemical weapons from the seabed could itself be highly dangerous.
In some cases, leaving the material in place under constant monitoring may be safer than disturbing it. Any recovery operation could increase the risk of containers breaking open and contaminated sediment spreading.
In 2021, the European Parliament adopted a resolution on chemical weapons and World War II shipwrecks in the Baltic Sea.
Members of the European Parliament said the problem was international and required cooperation among Baltic states, European Union institutions, and researchers working on safe methods to reduce the threat.
(rt/gs)
Source: IAR, PAP