Edgewood Chemical Biological Center APG United States
In separate, replicated experiments, we experimentally established wash-off coefficients kw for the chemical agent VX on grass, utilizing 1 and 3 L VX droplets at 0.017 1 min, 1, and 4 h after dissemination. A 10 mm 0.39 in. rain event at 0.017 h after dissemination washed off 95 and 83 of the 1 and 3 L VX droplets, respectively. At 1 h after dissemination, a 10 mm rain event washed off 0.03 and 0.5 of the 1 and 3 L VX droplets, respectively. At 0.017 h after dissemination, the kw values for 1 and 3 L droplets were 0.095 and 0.083 mm1, respectively. At 1 and 4 h after dissemination, the kw values for VX were approximately 3 orders of magnitude less than those at 0.017 h. Grass contaminated with 3 L VX droplets was exposed to multiple 10 100 L light rain events, followed by multiple 10 surface wipes at 0.017, 0.5, 1, 4, and 24 h after dissemination. The cumulative proportions of 3 L VX droplets washed off by the rain events at 0.017 and 1 h after dissemination were 75.3 and 0.99, respectively, and the cumulative proportions of VX wiped off after those rain events were 0.8 and 0.3, respectively. Results from these investigations of agentplant interactions provide input for predictive models and functional information for GoNo-Go decisions that can affect soldiers on agent-contaminated battlefields.