Dissipation of sarin, soman, and sulfur mustard from various types of crushed concrete

The behavior of chemical warfare agents (CWAs) on urban materials, such as concrete, significantly impacts forensic and military responses to chemical incidents. This study examined the persistence and degradation mechanisms of sarin (GB), soman (GD), and sulfur mustard (HD) on three types of commonly used concrete with varying water-cement ratios. Over two months, we evaluated the effects of concrete composition, temperature, and fragment size on CWA behavior. Half-lives and activation energies for CWA dissipation were calculated under various conditions. Results showed that concrete properties and external temperature strongly influenced dissipation rates. G-series agents underwent rapid hydrolysis, forming methylphosphonates, while HD degradation involved elimination, nucleophilic substitution, and oxidation, producing several previously unreported byproducts. Smaller concrete fragments increased recovery values and accelerated degradation due to greater surface area exposure, and higher temperatures further enhanced dissipation rates, particularly for volatile agents. Differences in dissipation among concrete types were linked to their physical and chemical properties, notably water-cement ratios. This study highlights the challenges of detecting CWAs due to their rapid penetration and transformation in concrete and provides insights for improving sampling, identification, and decontamination strategies under realistic conditions.