Fate of Nerve Agent Tabun in Concrete and Soil: Evaporation and Decontamination

Abstract

Abstract

This study reports on evaporation and decontamination of the nerve agent tabun from common civil surfaces, concrete and soil. Evaporation of various agent drop sizes was measured using a laboratory-sized wind tunnel and thermal desorber in combination with gas chromatography. Samples were periodically analyzed to determine the half-life of tabun at various temperatures, with and without a decontamination process. Results showed that in concrete, a drop of the agent was rapidly absorbed and spread into the matrix, while evaporating. In soil, a drop of the agent remained on the surface without spreading, while slowly evaporating. Not only does tabun remain longer in soil than in concrete but also the time required for evaporation was prolonged for larger drops. On the other hand, drops of the agent absorbed into the matrices remained for times after decontamination, following a pseudo first-order rate of degradation and decontamination. Estimated half-lives of tabun were 2 days in concrete and 5 days in soil at 25°C, which were shortened to 1.1 days in concrete and 1.8 days in soil at 50°C. The half-lives were significantly shortened after decontamination, to 4.6, 1.2, and 0.7 min in concrete and 5.9, 2.5, and 1.0 min in soil at 25°C, 35°C, and 50°C, respectively.