Transformation of unsymmetrical dimethylhydrazine in soils

Abstract

The transformation of unsymmetrical dimethylhydrazine (UDMH, a propellant component) applied at a rate of 240 g/kg to different soils was studied. The kinetic regularities of a decrease in the UDMH concentration and the accumulation of its transformation products leached out from dry and wet soils were investigated 3, 10, 30, and 90 days after its application. As the UDMH enters the soil, it vaporizes, and the elevated moisture of the soils promotes an increase in the pollutant's concentration at the initial moment; then, the concentration differences become leveled to the end of observation. It was also shown that the higher the organic matter content in the soil, the higher the UDMH concentration. However, at the end of the observations, on the 90th day, the total UDMH concentration did not exceed 0.5% of its initial content. In order to explain the UDMH behavior in the soils, one should take into account the existence of different forms of this substance and the changes in their ratios with time. The main portion of UDMH retained by the soil in the free form is transformed during the first few days. The products of the UDMH transformation, such as 1 methyl 1,2,4 triazole, formic acid dimethylhydrazide, dimethylguanidine, and dimethylamine are formed in considerable amounts, and their concentrations should be controlled in places of UDMH spills on soils.

Quantification of trace transformation products of rocket fuel unsymmetrical dimethylhydrazine in sand using vacuum-assisted headspace solid-phase microextraction

“…UDMH is a toxic, carcinogenic and mutagenic compound (U.S. EPA 1984; NIOSH 1997, 2018) posing a negative impact to the environment and human health (NIOSH 1997;Carlsen et al 2007Carlsen et al , 2008Carlsen et al , 2009. Trace amounts of UDMH transformation products (TPs) in soils can be detected several decades after the landing of rocket stage (Kenessov et al 2010b(Kenessov et al , 2012Rodin et al 2012;Kolesnikov 2014). Up until today, more than fty UDMH TPs were identi ed (Rodin et al 2008 Most prospective sample preparation methods for determination of UDMH TPs in soil samples (Kenessov et al 2010a(Kenessov et al , 2011Yegemova et al 2015;Bakaikina et al 2018;Orazbayeva et al 2018b) are based on headspace solid-phase microextraction (HSSPME).…”

Biodegradation of Unsymmetrical Dimethylhydrazine in Solution and Soil by Bacteria Isolated from Activated Sludge

“…UDMH may react with oxygen in the atmosphere, organic matter, and transition metal ions. In particular, UDMH may be tightly bound with the soil solid, which was a form including the UDMH adsorbed by the mineral phase and chemically adsorbed by the soil's organic matter [27]. In order to get a relatively stable UDMH concentration, the added solution made a water seal by saturating the soil samples.…”

“…The final UDMH concentration of the P4 + nSS + broth sample was 5.8 mg¨kg´1, and in the nSS + broth sample it was 12.3 mg¨kg´1. Given that UDMH could remain stable for a long time in the soil [27], the reduction in UDMH concentration can be attributed to the participation of the P4 strain. More experiments showed that the concentration of UDMH in soil underwent little change after five days, and the improvement of UDMH degrading percentage in the contaminated soil was a difficult process.…”

“…From Figure 6, one can see that the extra bacteria obviously improved the biodegrading ability of autochthonous microorganisms. Usually, a high concentration of UDMH, bonded with the soil solids in the form including the UDMH adsorbed by the mineral phase and chemically adsorbed by the soil organic matter, could exist for approximately 30 years [27,48]. Therefore, biodegradation of UDMH in the soil was a complicated process still influenced by organic matter, autochthonous microorganisms, and metal ions [49].…”

Products and Mechanistic Investigations on the Reactions of Hydrazines with Ozone in Gas-Phase

“…However, the experiment shows that the radical traps increase the NDMA formation [11]. Furthermore, various analytical techniques such as high performance liquid chromatography-mass spectroscopy (HPLC-MS) [16][17][18], gas chromatography-mass spectroscopy (GC-MS) [3,19,20], and solid phase micro-extraction (SPME-GC/MS) [21] have been used for the identification and quantitative determination of these transformation products, and more than 30 oxidative products have been identified. However, the information about the products of the hydrazines reaction with ozone is scarce, and the HO• influence on NDMA formation mechanism is still in discussion.…”