Migration and transformation of 1,1-dimethylhydrazine in peat bog soil of rocket stage fall site in Russian North.

An ingress of highly toxic rocket fuel 1,1-dimethylhydrazine (UDMH) and its transformation products into environment represents a serious negative impact on the ecosystem, as well as human health. The present research demonstrates the first data on the spatial distribution and quantification of UDMH and its main transformation products (methylhydrazine, hydrazine, 1,1,4,4-tetramethyltetrazene, formaldehyde, acetaldehyde and furaldehyde N,N-dimethylhydrazones, 1-formyl-2,2-dimethylhydrazine, N,N-dimethylformamide, N-nitrosodimethylamine, and 1-methyl-1H-1,2,4-triazole) in the peat bog soil of the fall site in subarctic region. One hundred samples of peat bog soil and one sample of surface water were analyzed by the developed earlier methodology. The considerable amounts of UDMH and most of its transformation products were found at distances of not >10 m from the center of the fall site. The maximum concentration of UDMH was found near the center, where maximal permissible concentration (MPC) was exceeded 2400-fold. The greatest pollution was observed in the surface soil layer, while methylhydrazine, 1-methyl-1H-1,2,4-triazole, 1-formyl-2,2-dimethylhydrazine, formaldehyde and acetaldehyde N,N-dimethylhydrazones, and N,N-dimethylformamide were the major UDMH transformation products. With increasing distance from the center, the composition of the transformation products changes in favor of the last three compounds. Formaldehyde N,N-dimethylhydrazone and N,N-dimethylformamide are present in all soil samples and can be considered as reliable markers of contamination with rocket fuel. The surface water of the peat bog contained four UDMH transformation products in considerable concentrations, including extremely toxic N-nitrosodimethylamine. The processes of migration and transformation of UDMH in peat bog soil differ considerably from those in sandy soils. This is due to cold climate of subarctic zone, the reducing environment of peat bog, and strong binding of hydrazines to organic matter of peat, which prevents migration of pollutants and contributes to the long-term maintenance of high levels of soil pollution.