Main chemical warfare compounds

Based on their effects, the chemical warfare agents can be classified into the following groups:

  • tear gases (lachrymators): chloroacetophenone (CAP),
  • nose and throat irritants: Clark I, Clark II, Adamsite,
  • lung irritants: phosgene, diphosgene,
  • blister gases (vesicants): sulphur mustard, nitrogen mustard, Lewisite,
  • nerve gases: tabun, and
  • additives, such as monochlorobenzene, are made to the warfare agents in order to change their physico-chemical properties.

Furthermore, the dumped chemical munitions might also contain certain amounts of explosives.

Most warfare agents are liquid or solid at 20°C; only phosgene is gaseous at temperatures above 8°C. All the compounds (with the exception of Tabun) are heavier than sea water and therefore do not float on the sea surface.

Chemical warfare agents produced in Germany between 1935 and 1945

 

 

Release into the environment

Corrosion of the chemical munitions will lead to the release of warfare agents into the marine environment. From the very moment the munitions are in contact with seawater the processes of corrosion from the metal containment will start. In general the corrosion rate will depend on the following parameters (Van Ham 2001):

  • temperature of the water - increase in temperature will favour corrosion;
  • percentage of oxygen in the water - oxygen will favour corrosion;
  • quality and thickness of the steel - steel with a high percentage of carbon has high corrosion rates;
  • presence of different metals in/on the steel body - a copper fuse or a brass burster charge will cause contact corrosion;
  • water current at the dumping side - a strong current guaranties the presence of water saturated with oxygen; also sand particles dragged in the current will contribute to the degradation process by mechanical erosion.

Already in the shell the toxic agent can be degraded. In addition some microorganisms are known to break the bonds in certain agents; their activity is often promoted by warm temperature, moisture and the presence of organic matter.

Behaviour in the marine environment

All warfare agents react with seawater, but reaction rates vary enormously depending on the chemical structure of the different agents. Some compounds show an extremely low solubility and slow degradability (e.g. Clark, Adamsite, viscous mustard gas).

Dissolution of the chemical warfare agents into the sea is the crucial first step in the degradation of the compounds. Besides a rise in temperature, current in particular speed up the process of dissolution.

The behaviour of chemical substances in the marine environment depends both on the chemical and physical-chemical properties of the substances and on environmental factors such as temperature, salinity and the pH value of the water. As the pH value of seawater is rather constant in the Baltic, salinity and temperature are the main environmental parameters that influence chemical reactions. The solubility of the compounds and the speed of reactions both increase with a rise in temperature. (Helcom 1994).

The behaviour of warfare agents in the marine environment is additionally influenced by the physical properties of the agents. For instance, a warfare agent in viscous or highly viscous form or in lump form can be caught in nets (e.g. mustard gas).

Missiaen, T., Paka, V., Emalyanov, E. (2006)

 
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