Estimating the Half-Lives of Key Components of the Chemical Vapor Signature of Land Mines
Abstract
The qualitative composition of the chemical signature of TNT-filled land mines is predominantly the isomers of dinitrotoluene (DNT), dinitrobenzene (DNB), and trinitrotoluene (TNT). These chemicals are known to undergo transformation in aerobic conditions, creating corresponding chemicals in which one of the nitro groups has been converted to an amino function. For these signatures to be available at the ground surface for detecting buried mines, the stability of these chemicals in the soil must exceed their rate of transport through the soil to the surface. This research investigates the rate of transformation of the major components of the signature of TNT- filled land mines in soil. A series of 5.0-g replicate portions of soil from a research minefield at Fort Leonard Wood, Missouri, was fortified with 2,4,6- trinitrotoluene, 2,4-and 2,6-dinitrotoluene, and 1,3-dinitrobenzene at about 0.5 mg/kg. Replicates were held at one of three temperatures (22 +/- 2, 4 +/- 2 or -4 +/- 2 degC) in the dark for periods ranging from 4 hours to 30 days and were then extracted with acetonitrile. The extracts were analyzed by reversed-phase HPLC to estimate the concentrations of the parent compounds and any detectable transformation products remaining. Concentrations of these compounds were plotted versus time and the rate of transformation for each compound estimated. While it doesn't appear that the process is kinetically first order, the half-life at 22 dgC was estimated to be about 1.3 days for 2,4,6-TNT, 9.9 days for 1,3-DNB, 18 days for 2,6-DNT and 26 days for 2,4-DNT At lower temperatures the half-lives were considerably longer, as expected.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2000
- Accession Number
- ADA382998
Entities
People
- Paul H. Miyares
- Thomas F. Jenkins
Organizations
- Engineer Research and Development Center