[katana]

That sounds more sinister but also a really stupid plan. Floating barrels shouldn't be hard to spot and recover, and are just as likely to end up caught in weeds along the side of a river as washed entirely out to the Gulf. If the intent was to kill Shiites in the south, it's going to take a long tme to work and will leave them plenty of incentive to move north and take it out on every Sunni they can catch. Interesting.

[MHGinTN]

Poisons dumped into the River or sunk in barreels in the River are the danger, not barrels floating down the River, for they may be retrieved and disposed of. The traces are more likely due to leakage from munitions dumped to the bottom of the River, and that will be a major problem to clean up once peace is established.