Why does Clark I remain in the marine environment for a long time?

• Published in: The Science of the total environment 2021-06, Vol.774, p.145675, Article 145675
• Main Authors: Nawała, Jakub, Gordon, Diana, Dziedzic, Daniel, Rodziewicz, Paweł, Popiel, Stanisław
• Format: Article
• Language: English
• Subjects: Chemical warfare agents (CWAs); Chromatographic analysis; Degradation pathways and kinetics; Diphenylchloroarsine (Clark I DA); Dumped munitions; Marine environment
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.145675

After World War II, based on decisions made at the Potsdam Conference in 1945, over 15,000 tons of chemical warfare agents (CWAs) were dumped in the Baltic Sea. These chemicals are still a threat to people and the maritime economy, but most of all to marine ecosystems. It is important to study the mechanisms of CWA reactions that could take place in the marine environment to evaluate the environmental risk. These studies are focused on the transformations of Clark I (diphenylchloroarsine, DA) in simulated Baltic Sea bottom sediments and water conditions. GC and LC methods for the analysis of Clark I and its degradation products were developed and applied. Clark I reactions in the bottom sediments and water environment were monitored systematically. This enabled the kinetics curves of Clark I degradation in various environments (matrix, temperature 4–70 °C, pH) to be determined and degradation products to be identified. Based on the kinetics curve reaction rates, the half-life period, reaction rate constants, and temperature coefficient (Q10) for water and sediment were established. These data allowed the activation energy for the hydrolysis reaction of DA in an aqueous environment to be ascertained, which was 69.2 kJ/mol. Clark I half-times in the conditions present in the Baltic Sea were about eight days for water and 18 days for sediment. [Display omitted] •Studies focused on the conversions of CWA named Clark I (DA) in the Sea sediments.•GC–MS/MS & LC-HRMS methods used for the analysis of DA & its degradation products•Determination of the kinetics of DA degradation in various environments•Ascertaining of the activation energy & half-times for the hydrolysis of DA•Explanation of the Clark I behavior in the marine environment