Chemical Weapons on the Sea Floor: A Plea for Complete Information

Ocean scientists have so far paid scant attention to the numerous sites and large quantities of chemical weapons (CW) disposed of on the sea floor, but the time for this inattention may now be past. In recent work we have shown that these sites are not well mapped, that there are no standards for marking or identification, and that unplanned scientific encroachment is beginning to occur. The time is ripe for a new scientific assessment [1] to accommodate safely the changing and intensifying modes of scientific exploration and uses of the ocean, and to assess the effects on marine life. In the years following World War II very large quantities of CW were disposed of in the ocean at numerous sites in the Atlantic, Pacific and Arctic Oceans, and in the Baltic and Adriatic Seas. Navigation inaccuracy from the dead-reckoning or celestial procedures available at that time, poor record keeping, and unauthorized disposal activities all contributed to confusion surrounding locations, quantities, and types of material. Thus navigation charts today do not present an adequate description of the affected areas. Offshore California some 12,000 km2 of sea floor are designated on US charts as CW disposal sites - yet an area of perhaps only 10% of this is likely of concern. In stark contrast US charts of waters offshore Japan show no CW sites - yet there are numerous known locations, often in shallow waters. There simply are no international standards or data bases available on which ocean scientists can plan expeditions. One example of an unplanned interaction of a scientific expedition with a suspected CW site came in 1992. The US Ocean Drilling Program drilled site 889 on the Cascadia Margin to examine gas hydrates, with site selection based on seismic surveys. Only at a late date was it discovered that this location was within 10 nm of a weapons disposal site, and a prohibition on sampling the uppermost 20 m of sediment was quickly put in place. Ocean hydrographic sampling lines often inadvertently transect CW site locations. The principal mode of decomposition of the primary agents is through hydrolysis, but the rates are usually estimated at normal oxygenated sea water pH of about 8. The lower pH (about 7) of typically anoxic sediment pore waters, encountered as materiel becomes buried, will greatly slow the reaction. These types of geochemical interactions should be considered in estimating the contaminant halo and lifetime. Here we highlight newly developed tools, such as in situ Raman spectroscopy, which can be used to remotely measure these materials and their breakdown products.