Adsorption/Desorption Measurements of Nitroglycerin and Dinitrotoluene in Camp Edwards, Massachusetts Soil

Abstract

Abstract : The mobility potential of nitroglycerin (NG) and dinitrotoluene (DNT) in small-arms range (SAR) soils was studied through a determination of adsorption and desorption. Measured laboratory batch-adsorption soil/water partitioning coefficients (Kds) for 2,4-DNT, 2,6-DNT, and NG ranged from 0.1 to 21.3, 0 to 18.2, and 0 to 7.3 L/kg, respectively. Mean adsorption Kd for 2,4-DNT and 2,6-DNT were 3.2 and 2.6 L/kg, respectively. The mean value for NG was 0.9 L/kg. The variables impacting adsorption were organic matter and cation exchange. Unfired and fired propellant tests suggest that NG and DNT is not completely avail-able for dissolution, and tests with weathered soils indicate none of the NG is available, although analysis shows NG is still present in the soil. Dissolution is the most important process in describing migration of deposited propellant compounds from SARs. Once released from nitrocellulose and dissolved in water, ad-sorption and degradation processes further limit NG and DNT mobility. Column experiments were conducted to augment batch tests. Nearly instantaneous breakthrough of NG was evident for the pair of columns containing aqueous NG/DNT with biocide. Results for the columns containing aqueous NG/DNT with-out biocide, fresh-fired propellant residue with biocide, and fresh-fired propellant residue without biocide indicated no breakthrough.