...although it may be extremely potent, would be composed primarily of the liquid agent which is in many cases water. So disseminating that into a body of sea water may affect only a limited range before the toxic chemical that was diluted in the original drops of liquid would be so far separated as to render it relatively harmless to most living matter in the ocean.
Now, taking a highly toxic chemical in its concentrated form, such as dioxin or plutonium and plunging say a kilogram or two of that into the sea would be an ecological disaster, because the molecules of the toxic substance would be much higher in mass and would disseminate over a much broader range of sea water, perhaps even throughout the entire oceans over time. That unfortunately is happening at this very moment with no monitoring, no accountability, no trace of the source(s).
We are all being slowly poisoned by our own folly and the list of these harmful and dangerous substances is endless. Dig deep for your information on this, it is so very important that the world be made aware before it is too late.
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Here was something I found that may provide additional leads for you to look for an answer to your question:
<snip>
TESTIMONY OF SCOTT B. GUDES
ACTING UNDER SECRETARY FOR OCEANS AND ATMOSPHERE
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
DEPARTMENT OF COMMERCE
BEFORE THE
SUBCOMMITTEE ON OCEANS, ATMOSPHERE, AND FISHERIES
COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION
U.S. SENATE
OCTOBER 11, 2001
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These capabilities are also suitable for dealing with chemical and biological threats. An urban monitoring system, including sensors to detect toxins and a high resolution model, could provide real time information to predict and track dispersion of chemical or
biological agents. A meteorological monitoring network for the Washington, D.C. area could be set up on a 24/7 basis within six months.
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<link>
http://www.legislative.noaa.gov/Testimony/101101gudes.html