Pollution: A time bomb under the Northern seas

16 November 2011
Trouw Amsterdam

Bombs away. Controlled blasting of WWII munition near Wisch, northern Germany, 2010.
Bombs away. Controlled blasting of WWII munition near Wisch, northern Germany, 2010.

The seas around Europe are threatened by a new source of pollution. Thousands of tonnes of chemical weapons will corrode and start to leak. In the Baltic, the possible consequences are being investigated.

Nobody knows exactly how many discarded chemical weapons are hidden in the waters around Europe. For instance, in the Baltic, where after World War II the Allies dumped munitions originating from German arsenals, there are at least 40,000 tonnes, of which at least 13,000 tonnes contain poisonous substances. A sixth of this amount would be sufficient to kill all life in the Baltic for a hundred years.

Not a reassuring idea, for anyone who knows that mustard gas, chloropicrin, phosgene, diphosgene and arsenic compounds are packed in cases and drums that will rust through sooner or later. No one knows when this will happen, but it is certain to.

Ten years ago, the Russian scientist Aleksander Korotenko predicted that somewhere between 2020 and 2060 the corrosion will have progressed so far that the poison will start to leak out. Sixteen percent is sufficient to wipe out all life in the Baltic.

"That's true, but it is very unlikely that all of that ammunition will rust through simultaneously", says Jacek Beldowski, putting the statement into perspective. He works at the Institute of Oceanology in Sopot, a seaside town in Poland. Beldowski is the coordinator of Chemsea (Chemical Munitions Search & Assess project), an international research project that started this October funded by a European subsidy.

"On the one hand the poison will leak out, on the other it becomes less hazardous when it comes into contact with water", says Beldowski. "The chemical weapons are distributed over an enormous area, and are subjected to very varying circumstances. Also, there are locations where they will not be exposed to oxygen, and therefore they will hardly corrode." So the problem is mainly one of uncertainty. "The only thing that is certain is, that in the coming years there will be a new form of pollution in the Baltic."

A lump of mustard gas among the herring

The results of the research in the Baltic will also provide valuable information for the North Sea, is the opinion of Katja Broeg from the Alfred Wegener Institute in Bremerhaven, one of the partners in the Chemsea project. "This is particularly the case where toxicological research is concerned. We catch fish on site and drop cages of mussels to see whether they develop cancer."

However, with respect to the spread of the poison, the North Sea and the Baltic are completely different, explains Broeg: "The North Sea is much more salty and has much stronger currents than the Baltic."

Chemsea’s and other research must, among other things, also provide guidelines for fishermen. What should you do if you find a 150mm shell among the cod? And what action do you take if you find a lump of mustard gas among the herring? Mustard gas does not escape in gaseous form, but turns into a sticky mass that can drift around in the sea for years. 

Shorty after the substances were dumped in the 1950’s, the first seaside holidaymakers in the GDR and Poland reported having mustard gas burns. Twenty-four serious accidents have occurred in Poland, the last one in 1997, when fishermen hauled up an enormous lump of mustard gas in their net.

However, the greatest risk is mechanical damage. For that reason, the authorities nearly everywhere decided not to recover the ammunition. Construction activities can have disastrous results if a large number of shells are damaged at the same time. This danger was reported extensively in the press thanks to Northstream, the gas pipeline running from Russia to Germany that crosses the Baltic.

According to Beldowski, the gas pipeline is only one example: "The seabed is increasingly being disturbed by construction projects: cables, wind farms and pipelines. Therefore procedures must be rapidly established for excavating, constructing and drilling in risk zones."

Sixty-four weapon dumps off the French coast

According to OSPAR – a collaborative agreement between North Sea countries – there are 31 places in the North Sea and the adjacent Atlantic Ocean where chemical weapons are corroding away. In addition, there are 120 dumping grounds for conventional weapons that are known to contain heavy metals and other hazardous substances, 64 of which are off the French coast.

After World War II, more than 1.5 million tonnes of ammunition were dumped, 90 tonnes of which were chemical weapons, in the German Bight, not very far from the Wadden Islands. In the Skagerrak between Denmark and Norway, the Allies sunk at least 45 ships carrying chemical weaponry. Between Ireland and Scotland, a million tonnes of ammunition were dumped in Beaufort's Dyke, a proportion of which were chemical weapons.

There are known to be two major toxic waste dumps in the Baltic: near the island of Bornholm and the Gotland basin, between the Swedish island of Gotland and the Baltic States. In the Mediterranean, the largest concentration can be found near the Italian city of Bari. Since World War II, 232 accidents were caused here by chemical waste, in particular mustard gas.

Tonnes of poisonous gas shells in Belgian waters

One of the largest chemical weapon dumps in the North Sea is situated off the Belgian coast, not very far from the Dutch border. The battlefields in Belgium were cleared after World War I. People were regularly killed during attempts to transport and store the weapons; therefore, at the end of 1919, the government in Brussels decided to dump them in the sea.

Every day for six months, a shipload of ammunition disappeared into the sea off the coast of Knokke Heist. "We don't know why they did not sail further out to sea. They probably wanted to get rid of their cargo as quickly as possible, as transporting it was also very dangerous", according to Tine Missiaen from the Renard Centre of Marine Geology in Gent.

The result is that the Paardenmarkt, a sandbank near the coast, is monitored annually. It is the final resting-place of at least 35,000 tonnes of ammunition, approximately a third of which are shells containing poisonous gas. Most have disappeared under a thick layer of sediment. In 1972, some of them were recovered from the water. They proved to be in remarkably good condition, thanks to the low-oxygen environment. At the time, serious corrosion still had to start.

Translated from the Dutch by Stuart Buck

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