What question did this study set out to answer?

This research aims to understand how unsymmetrical dimethylhydrazine (UDMH) degrades in various soil types and identify the key degradation pathways involved.

February 14, 2026Toxics0 citationsOpen Access

Degradation Dynamics and Pathways of Unsymmetrical Dimethylhydrazine (UDMH) Across Contrasting Soil Matrices: Insights from Controlled Incubation Experiments

JDJuan DuPLA Rocket Force University of Engineering XRXianghong RenPLA Rocket Force University of Engineering YZYizhi ZengPLA Rocket Force University of Engineering

Key Points

This research aims to understand how unsymmetrical dimethylhydrazine (UDMH) degrades in various soil types and identify the key degradation pathways involved.
Conducted controlled incubation experiments across three soil types: yellow-brown, red, and black soil.
Utilized headspace solid-phase microextraction (HS–SPME) for pretreatment and gas chromatography-mass spectrometry (GC–MS) for analysis.
Correlation analysis of soil physicochemical properties with UDMH degradation rates.
Identified UDMH and its transformation products during the incubation period.
UDMH degradation rates were 66.03% in yellow-brown soil, 67.51% in red soil, and 73.13% in black soil after 7 days.
Complete degradation of UDMH was observed within 30 days in all soil types.
Soil physicochemical properties significantly influenced UDMH degradation dynamics.
Degradation was governed predominantly by pathways like catalytic transformation and unidentified biotic-abiotic coupled processes.

Abstract

Unsymmetrical dimethylhydrazine (UDMH) serves as a high-performance liquid rocket propellant extensively utilized in the global aerospace industry, and its environmental release and leakage (particularly into soil systems) pose severe risks to ecological integrity and human health. As one of the few studies to quantitatively correlate soil physicochemical properties with UDMH degradation kinetics and pathway partitioning using controlled incubation experiments, this work aims to reveal the environmental hazards of UDMH in soil and provide a theoretical basis for subsequent remediation. The temporal degradation dynamics of UDMH in three comparative soil matrices (yellow-brown soil, red soil and black soil) were explored, correlations between soil physicochemical characteristics and UDMH degradation behavior were clarified, and UDMH degradation pathways were quantified. Headspace solid–phase microextraction (HS–SPME) was adopted as the pretreatment method, and gas chromatography–mass spectrometry (GC–MS) was used to identify UDMH and its transformation products (TPs) in soil incubation. From the GC–MS chromatogram, UDMH and its TPs—formaldehyde dimethylhydrazone (FDMH), acetaldehyde dimethylhydrazone (ADMH) and 1,1,4,4-tetramethyltetrazene (TMT)—were identified in the three soil matrices. UDMH underwent rapid degradation within the first 7 days of incubation, with degradation rates reaching 66.03%, 67.51% and 73.13% in yellow-brown soil (YS), red soil (RS) and black soil (BS), respectively. Degradation was most rapid in BS, followed by YS and RS. UDMH degraded completely and was undetectable within 30 days of soil incubation in the present study. Correlation analysis of soil physicochemical properties and UDMH degradation behavior revealed a significant influence of these edaphic properties on UDMH degradation dynamics across the tested soil matrices. The analysis of UDMH degradation pathways, including volatilization, photodegradation, microbiological degradation, and others (oxidation and self-degradation, etc.) demonstrated that other pathways (including catalytic transformation, induced transformation or unidentified biotic–abiotic coupled processes) acted as the dominant pathway governing its degradation (accounting for 68.75%). This study provides important insights and theoretical basis for unraveling the environmental fate of UDMH and remediating UDMH-contaminated soils.

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