Small Arms Live Fire: Study of Emitted Gaseous andParticulate Propellant Residues

摘要

A lot of work has been done during the past year in assessing the propellantresidue accumulation in near-surface soils at firing point areas in small arms rangesin Canada and the USA. Because (1) none of these ranges are used for a single type ofmunitions, (2) historical information is limited, and (3) soil is often contaminated frompast activities, the data obtained from range characterization only makes impossible theevaluation of the extent of contamination associated with the use of a specific ammunition/weapon system. There is not only a gap of knowledge on the buildup of propellantresidues on the ground, but there is also little information on the gaseous emissions resultingfrom the live firings. In order to properly advise the U.S. And Canadian Forces tosustain military training, and to help design alternative gun propellant formulations withbetter combustion properties than current ones, there is a need to better understand thegun propellant combustion and the parameters having an influence on the propellant efficiency.A study was thus undertaken to estimate the amount of unburned energetic residuesdeposited per round fired for 15 different small arms caliber/weapon systemsinvolving 9 mm, 7.62 mm, 5.56 mm, .50 cal, and .338 cal. For all trials, samples werecollected in aluminum plates strategically located in front of the gun. To identify the majorairborne contaminants and their concentrations, air samples were also collected for thethree most commonly used systems using pumps and enclosure bags to optimizesampling. All samples were analyzed by HPLC for nitroglycerin (NG) and 2,4-dinitrotoluene. Also, gas samples close to the weapon were taken using sorbent tubes andanalyzed for polycyclic aromatic hydrocarbons, total cyanides, the BTEX suite, aldehydes,and nitric acid. The percentage of unburned NG per round was found to vary between0.001% and 3.90%, and a quantity up to 2.03 mg NG per round was deposited,depending on the caliber/weapon used. From these results, the burning efficiency of mostsmall arms is better than mortars, but worse than some artillery rounds. Although theamount of dispersed NG per round seems low, the large amount of small caliber ammunitionfired in military training as compared to medium and large caliber ammunition canlead to the rapid accumulation on the soil surface. Moreover, the small arms residuesaccumulate in a much smaller area than those of mortars and artillery, leading to a higherconcentration buildup.